Genetics Tutorial Place your keyboard aside. Only use the mouse.

Genetics Tutorial Place your keyboard aside. Only use the mouse.
Start from beginning Purple vs. White Flowers Dominant vs. Recessive The F2 Generation 3:1 Ratios More 3:1 ratios Coincidence Genetics of Pea Plants Genotypes? Why the 3:1 ratio in the F2? Punnett Squares Mendel and Punnett squares The Adams Family Place your keyboard aside. Only use the mouse. The Davis Family

Back What is Genetics? Home Genetics is a branch of science that studies the patterns of heredity. This means that genetics tries to understand how traits are passed from parent to child. A better understanding of genetics and heredity will hopefully give those with genetic disorders a better quality of life as new medications and therapies can be designed to help treat illness.

Back What is Genetics? Home Genetics is a branch of science that studies the patterns of heredity. This means that genetics tries to understand how traits are passed from parent to child. A better understanding of genetics and heredity will hopefully give those with genetic disorders a better quality of life as new medications and therapies can be designed to help treat illness. Genetics didn’t start with studying human illness. Genetics grew it roots…in the soil…with plants. Pea plants to be exact. Gregor Mendel was an Austrian monk who worked in the garden of a monastery . Over many years, he uncovered the basics of genetics and heredity.

Back What is Genetics? Home Genetics is a branch of science that studies the patterns of heredity. This means that genetics tries to understand how traits are passed from parent to child. A better understanding of genetics and heredity will hopefully give those with genetic disorders a better quality of life as new medications and therapies can be designed to help treat illness. Genetics didn’t start with studying human illness. Genetics grew it roots…in the soil…with plants. Pea plants to be exact. Gregor Mendel was an Austrian monk who worked in the garden of a monastery . Over many years, he uncovered the basics of genetics and heredity. Gregor Mendel ( ) was a Monk who lived in Austria.

Back What is Genetics? Home Genetics is a branch of science that studies the patterns of heredity. This means that genetics tries to understand how traits are passed from parent to child. A better understanding of genetics and heredity will hopefully give those with genetic disorders a better quality of life as new medications and therapies can be designed to help treat illness. Genetics didn’t start with studying human illness. Genetics grew it roots…in the soil…with plants. Pea plants to be exact. Gregor Mendel was an Austrian monk who worked in the garden of a monastery . Over many years, he uncovered the basics of genetics and heredity. During the 8 years of experimentation, Mendel bred thousands of pea plants in the monastery garden.

Purple Flowers vs. White Flowers
Back Purple Flowers vs. White Flowers Home Mendel wanted to know what would happen when he mated (crossed) a pea plant with purple flower with a pea plant with white flowers. So using a brush, he rubbed pollen from 1 plant onto the other. This allowed them to exchange their genes. P Generation White flowered Purple flowered

Back Purple Flowers vs. White Flowers Home Mendel wanted to know what would happen when he mated (crossed) a pea plant with purple flower with a pea plant with white flowers. So using a brush, he rubbed pollen from 1 plant onto the other. This allowed them to exchange their genes. Mendel then planted the seeds produced and allowed them to grow in the monastery garden. The seeds grew into the next generation of pea plants, also known as the F1 generation. P Generation White flowered Purple flowered

Back Purple Flowers vs. White Flowers Home Mendel wanted to know what would happen when he mated (crossed) a pea plant with purple flower with a pea plant with white flowers. So using a brush, he rubbed pollen from 1 plant onto the other. This allowed them to exchange their genes. Mendel then planted the seeds produced and allowed them to grow in the monastery garden. The seeds grew into the next generation of pea plants, also known as the F1 generation. P Generation White flowered Purple flowered F1 Generation

Back Purple Flowers vs. White Flowers Home Mendel wanted to know what would happen when he mated (crossed) a pea plant with purple flower with a pea plant with white flowers. So using a brush, he rubbed pollen from 1 plant onto the other. This allowed them to exchange their genes. Mendel then planted the seeds produced and allowed them to grow in the monastery garden. The seeds grew into the next generation of pea plants, also known as the F1 generation. What happened to the gene for white? Even though every baby received a white gene, Mendel reasoned the purple gene was preventing the white gene from being expressed. Therefore the purple gene was called dominant. The hidden white gene was called recessive. P Generation White flowered Purple flowered F1 Generation

Back Dominant vs. Recessive Home Mendel examined 7 traits during his pea plant experimentation. The seven traits are shown above. Strangely, he found that when he allowed the pea plants to reproduce, certain traits were hidden while others were expressed in the baby plants.

Mendel found long stems to be dominant
Back Dominant vs. Recessive Home Mendel examined 7 traits during his pea plant experimentation. The seven traits are shown above. Strangely, he found that when he allowed the pea plants to reproduce, certain traits were hidden while others were expressed in the baby plants. Click your mouse on each picture to see which trait was dominant, and which was recessive. Mendel found long stems to be dominant

Mendel found yellow seeds to be dominant
Back Dominant vs. Recessive Home Mendel examined 7 traits during his pea plant experimentation. The seven traits are shown above. Strangely, he found that when he allowed the pea plants to reproduce, certain traits were hidden while others were expressed in the baby plants. Click your mouse on each picture to see which trait was dominant, and which was recessive. Mendel found yellow seeds to be dominant

Mendel found green pods to be dominant
Back Dominant vs. Recessive Home Mendel examined 7 traits during his pea plant experimentation. The seven traits are shown above. Strangely, he found that when he allowed the pea plants to reproduce, certain traits were hidden while others were expressed in the baby plants. Click your mouse on each picture to see which trait was dominant, and which was recessive. Mendel found green pods to be dominant

Mendel found purple flowers to be dominant
Back Dominant vs. Recessive Home Mendel examined 7 traits during his pea plant experimentation. The seven traits are shown above. Strangely, he found that when he allowed the pea plants to reproduce, certain traits were hidden while others were expressed in the baby plants. Click your mouse on each picture to see which trait was dominant, and which was recessive. Mendel found purple flowers to be dominant

Mendel found axial flower position to be dominant
Back Dominant vs. Recessive Home Mendel examined 7 traits during his pea plant experimentation. The seven traits are shown above. Strangely, he found that when he allowed the pea plants to reproduce, certain traits were hidden while others were expressed in the baby plants. Click your mouse on each picture to see which trait was dominant, and which was recessive. Mendel found axial flower position to be dominant

Mendel found inflated pods to be dominant
Back Dominant vs. Recessive Home Mendel found inflated pods to be dominant Mendel examined 7 traits during his pea plant experimentation. The seven traits are shown above. Strangely, he found that when he allowed the pea plants to reproduce, certain traits were hidden while others were expressed in the baby plants. Click your mouse on each picture to see which trait was dominant, and which was recessive.

Mendel found round seeds to be dominant
Back Dominant vs. Recessive Home Mendel examined 7 traits during his pea plant experimentation. The seven traits are shown above. Strangely, he found that when he allowed the pea plants to reproduce, certain traits were hidden while others were expressed in the baby plants. Click your mouse on each picture to see which trait was dominant, and which was recessive. Mendel found round seeds to be dominant

The F2 Generation P Generation F1 Generation F2 Generation
Back Home P Generation Many plants have both male and female sex organs and can self-pollinate and reproduce with itself. Mendel’s next step was to allow the newly created baby plants (F1 Generation) to self pollinate. He reasoned that because they all had a white flowered parent from the P generation, that maybe they still contained the instructions for white flowers. Purple flowered White flowered F1 Generation Purple flowered Purple flowered Purple flowered Purple flowered F2 Generation

Back The F2 Generation Home P Generation Many plants have both male and female sex organs and can self-pollinate and reproduce with itself. Mendel’s next step was to allow the newly created baby plants (F1 Generation) to self pollinate. He reasoned that because they all had a white flowered parent from the P generation, that maybe they still contained the instructions for white flowers. Purple flowered White flowered F1 Generation Purple flowered Purple flowered Purple flowered Purple flowered F2 Generation

Back The F2 Generation Home P Generation Many plants have both male and female sex organs and can self-pollinate and reproduce with itself. Mendel’s next step was to allow the newly created baby plants (F1 Generation) to self pollinate. He reasoned that because they all had a white flowered parent from the P generation, that maybe they still contained the instructions for white flowers. Just like before, they passed their genes to the next generation. But unlike before, white baby plants were created! How could this be? After all, both parents were purple in color! What percent of the pea plants were white? Purple flowered White flowered F1 Generation Purple flowered Purple flowered Purple flowered Purple flowered F2 Generation No No No No 0% 25% 50% 75% 100% Correct

Back 3:1 Ratios Home Approximately 25% of the flowers had white petals. In the picture above, you can see a 3:1 ratio, which is the exact same thing as 25%. For every 3 purple flowers, we can expect 1 white flower. 3 1

Back 3:1 Ratios Home Approximately 25% of the flowers had white petals. In the picture above, you can see a 3:1 ratio, which is the exact same thing as 25%. For every 3 purple flowers, we can expect 1 white flower. What about the other traits that Mendel observed? Flower color, Seed color, Pod color, Stem height, Flower position, Pod shape, Seed texture.

Back More 3:1 Ratios? Home So what about the other 7 traits Mendel examined? From the table, you can see he counted thousands of pea plants. Remember that Mendel was trying to find a pattern for heredity. Dominant Trait Recessive Ratio Flower color Purple 705 White 224 Seed color Yellow 6022 Green 2001 Seed shape Round 5474 Wrinkled 1850 Pod color 428 152 Pod shape 882 Constricted 299 Flower position Axial 651 Top 207 Plant height Tall 787 Dwarf 277

Back More 3:1 Ratios? Home So what about the other 7 traits Mendel examined? From the table, you can see he counted thousands of pea plants. Remember that Mendel was trying to find a pattern for heredity. Click the “question marks” to see the ratios he collected. Dominant Trait Recessive Ratio Flower color Purple 705 White 224 3.15:1 Seed color Yellow 6022 Green 2001 Seed shape Round 5474 Wrinkled 1850 Pod color 428 152 Pod shape 882 Constricted 299 Flower position Axial 651 Top 207 Plant height Tall 787 Dwarf 277 ?

Back More 3:1 Ratios? Home So what about the other 7 traits Mendel examined? From the table, you can see he counted thousands of pea plants. Remember that Mendel was trying to find a pattern for heredity. Click the “question marks” to see the ratios he collected. Dominant Trait Recessive Ratio Flower color Purple 705 White 224 3.15:1 Seed color Yellow 6022 Green 2001 3.01:1 Seed shape Round 5474 Wrinkled 1850 Pod color 428 152 Pod shape 882 Constricted 299 Flower position Axial 651 Top 207 Plant height Tall 787 Dwarf 277 ?

Back More 3:1 Ratios? Home So what about the other 7 traits Mendel examined? From the table, you can see he counted thousands of pea plants. Remember that Mendel was trying to find a pattern for heredity. Click the “question marks” to see the ratios he collected. Dominant Trait Recessive Ratio Flower color Purple 705 White 224 3.15:1 Seed color Yellow 6022 Green 2001 3.01:1 Seed shape Round 5474 Wrinkled 1850 2.96:1 Pod color 428 152 Pod shape 882 Constricted 299 Flower position Axial 651 Top 207 Plant height Tall 787 Dwarf 277 ?

Back More 3:1 Ratios? Home So what about the other 7 traits Mendel examined? From the table, you can see he counted thousands of pea plants. Remember that Mendel was trying to find a pattern for heredity. Click the “question marks” to see the ratios he collected. Dominant Trait Recessive Ratio Flower color Purple 705 White 224 3.15:1 Seed color Yellow 6022 Green 2001 3.01:1 Seed shape Round 5474 Wrinkled 1850 2.96:1 Pod color 428 152 2.82:1 Pod shape 882 Constricted 299 Flower position Axial 651 Top 207 Plant height Tall 787 Dwarf 277 ?

Back More 3:1 Ratios? Home So what about the other 7 traits Mendel examined? From the table, you can see he counted thousands of pea plants. Remember that Mendel was trying to find a pattern for heredity. Click the “question marks” to see the ratios he collected. Dominant Trait Recessive Ratio Flower color Purple 705 White 224 3.15:1 Seed color Yellow 6022 Green 2001 3.01:1 Seed shape Round 5474 Wrinkled 1850 2.96:1 Pod color 428 152 2.82:1 Pod shape 882 Constricted 299 2.95:1 Flower position Axial 651 Top 207 Plant height Tall 787 Dwarf 277 ?

Back More 3:1 Ratios? Home So what about the other 7 traits Mendel examined? From the table, you can see he counted thousands of pea plants. Remember that Mendel was trying to find a pattern for heredity. Click the “question marks” to see the ratios he collected. Dominant Trait Recessive Ratio Flower color Purple 705 White 224 3.15:1 Seed color Yellow 6022 Green 2001 3.01:1 Seed shape Round 5474 Wrinkled 1850 2.96:1 Pod color 428 152 2.82:1 Pod shape 882 Constricted 299 2.95:1 Flower position Axial 651 Top 207 3.14:1 Plant height Tall 787 Dwarf 277 ?

Back More 3:1 Ratios? Home So what about the other 7 traits Mendel examined? From the table, you can see he counted thousands of pea plants. Remember that Mendel was trying to find a pattern for heredity. Click the “question marks” to see the ratios he collected. Dominant Trait Recessive Ratio Flower color Purple 705 White 224 3.15:1 Seed color Yellow 6022 Green 2001 3.01:1 Seed shape Round 5474 Wrinkled 1850 2.96:1 Pod color 428 152 2.82:1 Pod shape 882 Constricted 299 2.95:1 Flower position Axial 651 Top 207 3.14:1 Plant height Tall 787 Dwarf 277 2.84:1 ?

Each has an approximate 3:1 ratio. This cannot be coincidence.
Back More 3:1 Ratios? Home So what about the other 7 traits Mendel examined? From the table, you can see he counted thousands of pea plants. Remember that Mendel was trying to find a pattern for heredity. Click the “question marks” to see the ratios he collected. Dominant Trait Recessive Ratio Flower color Purple 705 White 224 3.15:1 Seed color Yellow 6022 Green 2001 3.01:1 Seed shape Round 5474 Wrinkled 1850 2.96:1 Pod color 428 152 2.82:1 Pod shape 882 Constricted 299 2.95:1 Flower position Axial 651 Top 207 3.14:1 Plant height Tall 787 Dwarf 277 2.84:1 Each has an approximate 3:1 ratio. This cannot be coincidence.

Back More 3:1 Ratios? Home So what about the other 7 traits Mendel examined? From the table, you can see he counted thousands of pea plants. Remember that Mendel was trying to find a pattern for heredity. Click the “question marks” to see the ratios he collected. Even though it wasn’t perfect. We can see that every trait had about a 3:1 ratio of dominant to recessive features. If there were 3 yellow seeds for every 1 green seed, what percentage of plants had yellow seeds? Dominant Trait Recessive Ratio Flower color Purple 705 White 224 3.15:1 Seed color Yellow 6022 Green 2001 3.01:1 Seed shape Round 5474 Wrinkled 1850 2.96:1 Pod color 428 152 2.82:1 Pod shape 882 Constricted 299 2.95:1 Flower position Axial 651 Top 207 3.14:1 Plant height Tall 787 Dwarf 277 2.84:1 0% 25% 50% 75% 100% No No No No Correct

This 3:1 pattern keeps repeating. This cannot be coincidence.
Back Coincidence? Home Mendel was shocked to see that every recessive trait was expressed about 25% of the time and every dominant trait was expressed about 75% of the time. No way this can be coincidence! This 3:1 pattern keeps repeating. This cannot be coincidence.

Click to see other examples of traits that can skip generations
Back Coincidence? Home Mendel was shocked to see that every recessive trait was expressed about 25% of the time and every dominant trait was expressed about 75% of the time. No way this can be coincidence! Mendel’s conclusions changed science and the world forever. He concluded that 1 form of a gene can hide another form of a gene. For example, the purple form of a gene would hide the white form of a gene. This now explained why some traits and diseases would skip generations. Click to see other examples of traits that can skip generations

Coincidence? Male Pattern Baldness
Back Coincidence? Home Mendel was shocked to see that every recessive trait was expressed about 25% of the time and every dominant trait was expressed about 75% of the time. No way this can be coincidence! Mendel’s conclusions changed science and the world forever. He concluded that 1 form of a gene can hide another form of a gene. For example, the purple form of a gene would hide the white form of a gene. This now explained why some traits and diseases would skip generations. Male Pattern Baldness

Back Coincidence? Home Mendel was shocked to see that every recessive trait was expressed about 25% of the time and every dominant trait was expressed about 75% of the time. No way this can be coincidence! Mendel’s conclusions changed science and the world forever. He concluded that 1 form of a gene can hide another form of a gene. For example, the purple form of a gene would hide the white form of a gene. This now explained why some traits and diseases would skip generations. Normal red blood cells are round and flow through narrow veins and arteries.

Back Coincidence? Home Mendel was shocked to see that every recessive trait was expressed about 25% of the time and every dominant trait was expressed about 75% of the time. No way this can be coincidence! Mendel’s conclusions changed science and the world forever. He concluded that 1 form of a gene can hide another form of a gene. For example, the purple form of a gene would hide the white form of a gene. This now explained why some traits and diseases would skip generations. Normal red blood cells are round and flow through narrow veins and arteries. “Sickle” shaped red blood cells can more easily clog narrow veins and arteries.

Coincidence? Cystic fibrosis (CF)
Back Coincidence? Home Mendel was shocked to see that every recessive trait was expressed about 25% of the time and every dominant trait was expressed about 75% of the time. No way this can be coincidence! Mendel’s conclusions changed science and the world forever. He concluded that 1 form of a gene can hide another form of a gene. For example, the purple form of a gene would hide the white form of a gene. This now explained why some traits and diseases would skip generations. Cystic fibrosis (CF)

Back Coincidence? Home Mendel was shocked to see that every recessive trait was expressed about 25% of the time and every dominant trait was expressed about 75% of the time. No way this can be coincidence! Mendel’s conclusions changed science and the world forever. He concluded that 1 form of a gene can hide another form of a gene. For example, the purple form of a gene would hide the white form of a gene. This now explained why some traits and diseases would skip generations. Even though Mendel didn’t know it. His work would later be used to help predict and treat genetic illnesses.

The Genetics of Pea Plants
Back The Genetics of Pea Plants Home P Generation The gene for flower color come in two varieties: purple and white. These alternative forms of a gene are called alleles. Purple flowered White flowered F1 Generation

Back The Genetics of Pea Plants Home P Generation The gene for flower color come in two varieties: purple and white. These alternative forms of a gene are called alleles. Why did 100% of the F1 generation have purple flowers? The purple parent contains two alleles for purple flowers. Capital letters represent the two dominant alleles (PP). Purple flowered White flowered F1 Generation

Back The Genetics of Pea Plants Home P Generation The gene for flower color come in two varieties: purple and white. These alternative forms of a gene are called alleles. Why did 100% of the F1 generation have purple flowers? The purple parent contains two alleles for purple flowers. Capital letters represent the two dominant alleles (PP). Purple flowered White flowered P P F1 Generation

Back The Genetics of Pea Plants Home P Generation The gene for flower color come in two varieties: purple and white. These alternative forms of a gene are called alleles. Why did 100% of the F1 generation have purple flowers? The purple parent contains two alleles for purple flowers. Capital letters represent the two dominant alleles (PP). The white flowered parent has two alleles for white flowers. We use lowercase letters to abbreviate the two recessive alleles (pp). Purple flowered White flowered P P F1 Generation

Back The Genetics of Pea Plants Home P Generation The gene for flower color come in two varieties: purple and white. These alternative forms of a gene are called alleles. Why did 100% of the F1 generation have purple flowers? The purple parent contains two alleles for purple flowers. Capital letters represent the two dominant alleles (PP). The white flowered parent has two alleles for white flowers. We use lowercase letters to abbreviate the two recessive alleles (pp). Purple flowered White flowered P P p p F1 Generation

Back The Genetics of Pea Plants Home P Generation The gene for flower color come in two varieties: purple and white. These alternative forms of a gene are called alleles. Why did 100% of the F1 generation have purple flowers? The purple parent contains two alleles for purple flowers. Capital letters represent the two dominant alleles (PP). The white flowered parent has two alleles for white flowers. We use lowercase letters to abbreviate the two recessive alleles (pp). When these two plants reproduced, the purple parent contributed a purple allele… Purple flowered White flowered P P p p F1 Generation

Back The Genetics of Pea Plants Home P Generation The gene for flower color come in two varieties: purple and white. These alternative forms of a gene are called alleles. Why did 100% of the F1 generation have purple flowers? The purple parent contains two alleles for purple flowers. Capital letters represent the two dominant alleles (PP). The white flowered parent has two alleles for white flowers. We use lowercase letters to abbreviate the two recessive alleles (pp). When these two plants reproduced, the purple parent contributed a purple allele… Purple flowered White flowered P P P P P P p p F1 Generation

Back The Genetics of Pea Plants Home P Generation The gene for flower color come in two varieties: purple and white. These alternative forms of a gene are called alleles. Why did 100% of the F1 generation have purple flowers? The purple parent contains two alleles for purple flowers. Capital letters represent the two dominant alleles (PP). The white flowered parent has two alleles for white flowers. We use lowercase letters to abbreviate the two recessive alleles (pp). When these two plants reproduced, the purple parent contributed a purple allele… The white parent contributed a white allele… Purple flowered White flowered P P P P p p F1 Generation P P P P

Back The Genetics of Pea Plants Home P Generation The gene for flower color come in two varieties: purple and white. These alternative forms of a gene are called alleles. Why did 100% of the F1 generation have purple flowers? The purple parent contains two alleles for purple flowers. Capital letters represent the two dominant alleles (PP). The white flowered parent has two alleles for white flowers. We use lowercase letters to abbreviate the two recessive alleles (pp). When these two plants reproduced, the purple parent contributed a purple allele… The white parent contributed a white allele… Purple flowered White flowered P P P P p p p p p p F1 Generation P P P P

Back The Genetics of Pea Plants Home P p P Generation Purple flowered White flowered F1 Generation The gene for flower color come in two varieties: purple and white. These alternative forms of a gene are called alleles. Why did 100% of the F1 generation have purple flowers? The purple parent contains two alleles for purple flowers. Capital letters represent the two dominant alleles (PP). The white flowered parent has two alleles for white flowers. We use lowercase letters to abbreviate the two recessive alleles (pp). When these two plants reproduced, the purple parent contributed a purple allele… The white parent contributed a white allele… This is why 100% of the F1 generation was purple in color. Each offspring received a dominant purple allele.

Back Genotypes? Home These are chromosomes. Remember we have two of every chromosome. For example, we inherit one chromosome #12 from our mother, and one chromosome #12 from our father. P p P p

Back Genotypes? Home These are chromosomes. Remember we have two of every chromosome. For example, we inherit one chromosome #12 from our mother, and one chromosome #12 from our father. The actual allele combination that an organism contains is called it's genotype. Organisms have one of the three possible combinations you see above. Click on the chromosomes above to see their names. P Click the picture p P p

Two dominant alleles is called Homozygous Dominant.
Back Genotypes? Home Two dominant alleles is called Homozygous Dominant. These are chromosomes. Remember we have two of every chromosome. For example, we inherit one chromosome #12 from our mother, and one chromosome #12 from our father. The actual allele combination that an organism contains is called it's genotype. Organisms have one of the three possible combinations you see above. Click on the chromosomes above to see their names. P Click the picture p P p

Back Genotypes? Home Two dominant alleles is called Homozygous Dominant. Two recessive alleles is called Homozygous Recessive. These are chromosomes. Remember we have two of every chromosome. For example, we inherit one chromosome #12 from our mother, and one chromosome #12 from our father. The actual allele combination that an organism contains is called it's genotype. Organisms have one of the three possible combinations you see above. Click on the chromosomes above to see their names. P p P p Click the picture

Back Genotypes? Home Two dominant alleles is called Homozygous Dominant. Two recessive alleles is called Homozygous Recessive. One dominant & one recessive allele is called Heterozygous. These are chromosomes. Remember we have two of every chromosome. For example, we inherit one chromosome #12 from our mother, and one chromosome #12 from our father. The actual allele combination that an organism contains is called it's genotype. Organisms have one of the three possible combinations you see above. Click on the chromosomes above to see their names. P p P p

Genotypes? P P Generation p F1 Generation
Back Genotypes? Home P p P Generation Purple flowered White flowered F1 Generation These are chromosomes. Remember we have two of every chromosome. For example, we inherit one chromosome #12 from our mother, and one chromosome #12 from our father. The actual allele combination that an organism contains is called it's genotype. Organisms have one of the three possible combinations you see above. Click on the chromosomes above to see their names. Remember that the F1 generation was created from a purple parent (PP) and a white parent (pp), but all the babies were purple (Pp) in color. What do you think was the genotype of the F1 generation? Homozygous dominant Homozygous recessive Heterozygous correct

Why the 3:1 Ratio in the F2 Generation?
Back Why the 3:1 Ratio in the F2 Generation? Home When Mendel bred the F1 generation, the seeds produced were allowed to grow in his garden. Eventually, 75% of the F2 generation grew purple flowers and 25% grew white flowers. This is the 3:1 ratio Mendel uncovered. But how can genetics explain this pattern? F1 Generation F2 Generation

Back Why the 3:1 Ratio in the F2 Generation? Home When Mendel bred the F1 generation, the seeds produced were allowed to grow in his garden. Eventually, 75% of the F2 generation grew purple flowers and 25% grew white flowers. This is the 3:1 ratio Mendel uncovered. But how can genetics explain this pattern? The F1 generation were all heterozygous (Pp). F1 Generation F2 Generation

Back Why the 3:1 Ratio in the F2 Generation? Home When Mendel bred the F1 generation, the seeds produced were allowed to grow in his garden. Eventually, 75% of the F2 generation grew purple flowers and 25% grew white flowers. This is the 3:1 ratio Mendel uncovered. But how can genetics explain this pattern? The F1 generation were all heterozygous (Pp). F1 Generation P P p p F2 Generation

Back Why the 3:1 Ratio in the F2 Generation? Home When Mendel bred the F1 generation, the seeds produced were allowed to grow in his garden. Eventually, 75% of the F2 generation grew purple flowers and 25% grew white flowers. This is the 3:1 ratio Mendel uncovered. But how can genetics explain this pattern? The F1 generation were all heterozygous (Pp). There are four different combinations of alleles in the F2 generation. F1 Generation P P p p F2 Generation

Back Why the 3:1 Ratio in the F2 Generation? Home When Mendel bred the F1 generation, the seeds produced were allowed to grow in his garden. Eventually, 75% of the F2 generation grew purple flowers and 25% grew white flowers. This is the 3:1 ratio Mendel uncovered. But how can genetics explain this pattern? The F1 generation were all heterozygous (Pp). There are four different combinations of alleles in the F2 generation. F1 Generation P P P P p p F2 Generation Homozygous dominant

Back Why the 3:1 Ratio in the F2 Generation? Home When Mendel bred the F1 generation, the seeds produced were allowed to grow in his garden. Eventually, 75% of the F2 generation grew purple flowers and 25% grew white flowers. This is the 3:1 ratio Mendel uncovered. But how can genetics explain this pattern? The F1 generation were all heterozygous (Pp). There are four different combinations of alleles in the F2 generation. F1 Generation P P P p p p F2 Generation P P Homozygous dominant Heterozygous

Back Why the 3:1 Ratio in the F2 Generation? Home When Mendel bred the F1 generation, the seeds produced were allowed to grow in his garden. Eventually, 75% of the F2 generation grew purple flowers and 25% grew white flowers. This is the 3:1 ratio Mendel uncovered. But how can genetics explain this pattern? The F1 generation were all heterozygous (Pp). There are four different combinations of alleles in the F2 generation. F1 Generation P P P p p p F2 Generation P P P p Homozygous dominant Heterozygous Heterozygous

Back Why the 3:1 Ratio in the F2 Generation? Home When Mendel bred the F1 generation, the seeds produced were allowed to grow in his garden. Eventually, 75% of the F2 generation grew purple flowers and 25% grew white flowers. This is the 3:1 ratio Mendel uncovered. But how can genetics explain this pattern? The F1 generation were all heterozygous (Pp). There are four different combinations of alleles in the F2 generation. F1 Generation P P p p p p F2 Generation P P P P p p Homozygous dominant Heterozygous Heterozygous Homozygous recessive

Back Why the 3:1 Ratio in the F2 Generation? Home When Mendel bred the F1 generation, the seeds produced were allowed to grow in his garden. Eventually, 75% of the F2 generation grew purple flowers and 25% grew white flowers. This is the 3:1 ratio Mendel uncovered. But how can genetics explain this pattern? The F1 generation were all heterozygous (Pp). There are four different combinations of alleles in the F2 generation. Mendel’s observations now made sense. Because 3 of every 4 flowers in the F2 generation inherited a dominant purple allele, “P”, this explains why Mendel observed a 3:1 ratio of purple to white flowers. F1 Generation P P p p F2 Generation P P P P p p p p Homozygous dominant Heterozygous Heterozygous Homozygous recessive

Back Punnett Squares Home Reginald Punnett created a mathematics tool called a Punnett square to help solve genetics problems.

Back Punnett Squares Home Reginald Punnett created a mathematics tool called a Punnett square to help solve genetics problems. Punnett squares help scientists to predict genetic combinations from simple traits such as flower color to serious disorders such as cystic fibrosis. By predicting genetic disorders, information can be given to families who have a history of genetic illnesses. This will allow the family to make informed, educated decisions about the future health of their child or children. So let’s see how to create them…

Mendel and Punnett Squares
Back Mendel and Punnett Squares Home Reginald Punnett used the information gained by Mendel to create charts to help predict probabilities. Let’s examine the data Mendel collected for pea plant height. Tall was dominant (T) and short was recessive (t).

Back Mendel and Punnett Squares Home Reginald Punnett used the information gained by Mendel to create charts to help predict probabilities. Let’s examine the data Mendel collected for pea plant height. Tall was dominant (T) and short was recessive (t). Let’s examine Mendel’s F1 generation using a Punnett square.

Back Mendel and Punnett Squares Home Reginald Punnett used the information gained by Mendel to create charts to help predict probabilities. Let’s examine the data Mendel collected for pea plant height. Tall was dominant (T) and short was recessive (t). Let’s examine Mendel’s F1 generation using a Punnett square. Since Tall is dominant to short, we will use “T” to represent tall and “t” to represent short.

Back Mendel and Punnett Squares Home Reginald Punnett used the information gained by Mendel to create charts to help predict probabilities. Let’s examine the data Mendel collected for pea plant height. Tall was dominant (T) and short was recessive (t). Let’s examine Mendel’s F1 generation using a Punnett square. Since Tall is dominant to short, we will use “T” to represent tall and “t” to represent short. If a plant is homozygous dominant, the genotype would be “TT”

Back Mendel and Punnett Squares Home Reginald Punnett used the information gained by Mendel to create charts to help predict probabilities. Let’s examine the data Mendel collected for pea plant height. Tall was dominant (T) and short was recessive (t). Let’s examine Mendel’s F1 generation using a Punnett square. Since Tall is dominant to short, we will use “T” to represent tall and “t” to represent short. If a plant is homozygous dominant, the genotype would be “TT” If a plant is homozygous recessive, the genotype would be “tt”

Back Mendel and Punnett Squares Home Reginald Punnett used the information gained by Mendel to create charts to help predict probabilities. Let’s examine the data Mendel collected for pea plant height. Tall was dominant (T) and short was recessive (t). Let’s examine Mendel’s F1 generation using a Punnett square. Since Tall is dominant to short, we will use “T” to represent tall and “t” to represent short. If a plant is homozygous dominant, the genotype would be “TT” If a plant is homozygous recessive, the genotype would be “tt” If a plant is heterozygous, the genotype would be “Tt”

Back Mendel and Punnett Squares Home Reginald Punnett used the information gained by Mendel to create charts to help predict probabilities. Let’s examine the data Mendel collected for pea plant height. Tall was dominant (T) and short was recessive (t). Let’s examine Mendel’s F1 generation using a Punnett square. In the F1 generation, Mendel allowed a heterozygous Tall (Tt) plant to self pollinate. Therefore, the DNA in the male pollen was “Tt” and the DNA in the female egg also “Tt”. Since Tall is dominant to short, we will use “T” to represent tall and “t” to represent short. If a plant is homozygous dominant, the genotype would be “TT” If a plant is homozygous recessive, the genotype would be “tt” If a plant is heterozygous, the genotype would be “Tt”

Back Mendel and Punnett Squares Home Reginald Punnett used the information gained by Mendel to create charts to help predict probabilities. Let’s examine the data Mendel collected for pea plant height. Tall was dominant (T) and short was recessive (t). Let’s examine Mendel’s F1 generation using a Punnett square. In the F1 generation, Mendel allowed a heterozygous Tall (Tt) plant to self pollinate. Therefore, the DNA in the male pollen was “Tt” and the DNA in the female egg also “Tt”. Male plant Female plant T t

Back Mendel and Punnett Squares Home Reginald Punnett used the information gained by Mendel to create charts to help predict probabilities. Let’s examine the data Mendel collected for pea plant height. Tall was dominant (T) and short was recessive (t). Let’s examine Mendel’s F1 generation using a Punnett square. In the F1 generation, Mendel allowed a heterozygous Tall (Tt) plant to self pollinate. Therefore, the DNA in the male pollen was “Tt” and the DNA in the female egg also “Tt”. Male plant Female plant T t T t 1st step: Place the genotypes of each parent on the outside of the Punnett square.

Back Mendel and Punnett Squares Home Reginald Punnett used the information gained by Mendel to create charts to help predict probabilities. Let’s examine the data Mendel collected for pea plant height. Tall was dominant (T) and short was recessive (t). Let’s examine Mendel’s F1 generation using a Punnett square. In the F1 generation, Mendel allowed a heterozygous Tall (Tt) plant to self pollinate. Therefore, the DNA in the male pollen was “Tt” and the DNA in the female egg also “Tt”. Male plant Female plant T T t t T T t t

Back Mendel and Punnett Squares Home Reginald Punnett used the information gained by Mendel to create charts to help predict probabilities. Let’s examine the data Mendel collected for pea plant height. Tall was dominant (T) and short was recessive (t). Let’s examine Mendel’s F1 generation using a Punnett square. In the F1 generation, Mendel allowed a heterozygous Tall (Tt) plant to self pollinate. Therefore, the DNA in the male pollen was “Tt” and the DNA in the female egg also “Tt”. Male plant Female plant T t T t 2nd step: Fill in the Punnett squares. T t T t

Back Mendel and Punnett Squares Home Reginald Punnett used the information gained by Mendel to create charts to help predict probabilities. Let’s examine the data Mendel collected for pea plant height. Tall was dominant (T) and short was recessive (t). Let’s examine Mendel’s F1 generation using a Punnett square. In the F1 generation, Mendel allowed a heterozygous Tall (Tt) plant to self pollinate. Therefore, the DNA in the male pollen was “Tt” and the DNA in the female egg also “Tt”. Male plant Female plant T t T t T T T t t t T T T t t t

Back Mendel and Punnett Squares Home Reginald Punnett used the information gained by Mendel to create charts to help predict probabilities. Let’s examine the data Mendel collected for pea plant height. Tall was dominant (T) and short was recessive (t). Let’s examine Mendel’s F1 generation using a Punnett square. In the F1 generation, Mendel allowed a heterozygous Tall (Tt) plant to self pollinate. Therefore, the DNA in the male pollen was “Tt” and the DNA in the female egg also “Tt”. Male plant Female plant T t T t Will this genotype represent a tall or short plant? X Tall Short T T T t t t T T T T T T t t t t t t T t t t t t t t t t Now lets analyze the Punnett square.

Back Mendel and Punnett Squares Home Reginald Punnett used the information gained by Mendel to create charts to help predict probabilities. Let’s examine the data Mendel collected for pea plant height. Tall was dominant (T) and short was recessive (t). Let’s examine Mendel’s F1 generation using a Punnett square. In the F1 generation, Mendel allowed a heterozygous Tall (Tt) plant to self pollinate. Therefore, the DNA in the male pollen was “Tt” and the DNA in the female egg also “Tt”. Male plant Female plant Will this genotype represent a tall or short plant? T t T t X Tall Short T T T t t t T T T T T T t t t Tall t t t T t t t t t t t t t Now lets analyze the Punnett square.

Back Mendel and Punnett Squares Home Reginald Punnett used the information gained by Mendel to create charts to help predict probabilities. Let’s examine the data Mendel collected for pea plant height. Tall was dominant (T) and short was recessive (t). Let’s examine Mendel’s F1 generation using a Punnett square. In the F1 generation, Mendel allowed a heterozygous Tall (Tt) plant to self pollinate. Therefore, the DNA in the male pollen was “Tt” and the DNA in the female egg also “Tt”. Male plant Female plant T t T t T T T t t t Will this genotype represent a tall or short plant? T T T T T T t t t X Tall Tall Tall Short t t t T t t t t t t t t t Now lets analyze the Punnett square.

Back Mendel and Punnett Squares Home Reginald Punnett used the information gained by Mendel to create charts to help predict probabilities. Let’s examine the data Mendel collected for pea plant height. Tall was dominant (T) and short was recessive (t). Let’s examine Mendel’s F1 generation using a Punnett square. In the F1 generation, Mendel allowed a heterozygous Tall (Tt) plant to self pollinate. Therefore, the DNA in the male pollen was “Tt” and the DNA in the female egg also “Tt”. Male plant Female plant T t T t Will this genotype represent a tall or short plant? T T T t t t X Tall Short T T T T t t t Tall Tall T t T t t t Now lets analyze the Punnett square. Tall

Back Mendel and Punnett Squares Home Reginald Punnett used the information gained by Mendel to create charts to help predict probabilities. Let’s examine the data Mendel collected for pea plant height. Tall was dominant (T) and short was recessive (t). Let’s examine Mendel’s F1 generation using a Punnett square. In the F1 generation, Mendel allowed a heterozygous Tall (Tt) plant to self pollinate. Therefore, the DNA in the male pollen was “Tt” and the DNA in the female egg also “Tt”. Male plant Female plant T t T t T t t t T T T T t Tall Tall t T t t t t t Now lets analyze the Punnett square. Tall Short

Back Mendel and Punnett Squares Home What is the probability of a plant growing short? Male plant Female plant T t T t 0% Look again Correct 25% t T Tall Short 50% Look again Look again 75% 100% Look again

Back Mendel and Punnett Squares Home What is the probability of a plant growing heterozygous? Male plant Female plant T t T t 0% Look again 25% Look again Correct t T Tall Short 50% Look again 75% 100% Look again

Back Mendel and Punnett Squares Home Click on the homozygous recessive genotype. Male plant Female plant T t T t t T Tall Short X X X correct

Back Mendel and Punnett Squares Home Good job…But we can use this information to predict more than pea traits too. Let’s use Mendel’s and Punnett’s work to help people who have genetic problems. Male plant Female plant T t T t t T Tall Short My pea plant experiments are helping people? Show me how please.

Back The Adams Family Home The gene that causes cystic fibrosis can be found on chromosome #7. Mr. and Mrs. Adams have tested to be heterozygous/carriers of cystic fibrosis. This means that each is healthy because they have a dominant healthy allele (H) on one of their chromosome #7s and a faulty recessive allele (h) on their other chromosome #7.

Since healthy is dominant, I’m going to use “H” to represent healthy.
Back The Adams Family Home Since healthy is dominant, I’m going to use “H” to represent healthy. The gene that causes cystic fibrosis can be found on chromosome #7. Mr. and Mrs. Adams have tested to be heterozygous/carriers of cystic fibrosis. This means that each is healthy because they have a dominant healthy allele (H) on one of their chromosome #7s and a faulty recessive allele (h) on their other chromosome #7. H = healthy

The allele that causes cystic fibrosis is recessive, so I’ll use “h”.
Back The Adams Family Home The gene that causes cystic fibrosis can be found on chromosome #7. Mr. and Mrs. Adams have tested to be heterozygous/carriers of cystic fibrosis. This means that each is healthy because they have a dominant healthy allele (H) on one of their chromosome #7s and a faulty recessive allele (h) on their other chromosome #7. The allele that causes cystic fibrosis is recessive, so I’ll use “h”. H = healthy h = cystic fibrosis

Back The Adams Family Home That’s correct. I inherited the allele from my mother. The gene that causes cystic fibrosis can be found on chromosome #7. Mr. and Mrs. Adams have tested to be heterozygous/carriers of cystic fibrosis. This means that each is healthy because they have a dominant healthy allele (H) on one of their chromosome #7s and a faulty recessive allele (h) on their other chromosome #7. Mr. Adams… your genotype is “Hh”. H = healthy Mr. Adams = Hh h = cystic fibrosis

Back The Adams Family Home Yes. You can also call me a “carrier” of cystic fibrosis. The gene that causes cystic fibrosis can be found on chromosome #7. Mr. and Mrs. Adams have tested to be heterozygous/carriers of cystic fibrosis. This means that each is healthy because they have a dominant healthy allele (H) on one of their chromosome #7s and a faulty recessive allele (h) on their other chromosome #7. Mrs. Adams… your genotype is also heterozygous “Hh”. H = healthy Mr. Adams = Hh Mrs. Adams = Hh h = cystic fibrosis

Back The Adams Family Home Lets add both of your genotype’s to the outside of this Punnett square. The gene that causes cystic fibrosis can be found on chromosome #7. Mr. and Mrs. Adams have tested to be heterozygous/carriers of cystic fibrosis. This means that each is healthy because they have a dominant healthy allele (H) on one of their chromosome #7s and a faulty recessive allele (h) on their other chromosome #7. H = healthy Mr. Adams = Hh Mrs. Adams = Hh h = cystic fibrosis

Back The Adams Family Home Lets add both of your genotype’s to the outside of this Punnett square. The gene that causes cystic fibrosis can be found on chromosome #7. Mr. and Mrs. Adams have tested to be heterozygous/carriers of cystic fibrosis. This means that each is healthy because they have a dominant healthy allele (H) on one of their chromosome #7s and a faulty recessive allele (h) on their other chromosome #7. H h H h H = healthy Mr. Adams = Hh Mrs. Adams = Hh h = cystic fibrosis

Back The Adams Family Home Now we just fill in the empty Punnett squares. I like to place the capital letter first. The gene that causes cystic fibrosis can be found on chromosome #7. Mr. and Mrs. Adams have tested to be heterozygous/carriers of cystic fibrosis. This means that each is healthy because they have a dominant healthy allele (H) on one of their chromosome #7s and a faulty recessive allele (h) on their other chromosome #7. H h H h H = healthy Mr. Adams = Hh Mrs. Adams = Hh h = cystic fibrosis

The Adams Family H h H H H H h h H h h h
Back The Adams Family Home Now we just fill in the empty Punnett squares. I like to place the capital letter first. The gene that causes cystic fibrosis can be found on chromosome #7. Mr. and Mrs. Adams have tested to be heterozygous/carriers of cystic fibrosis. This means that each is healthy because they have a dominant healthy allele (H) on one of their chromosome #7s and a faulty recessive allele (h) on their other chromosome #7. H h H H H H h h H h h h H = healthy Mr. Adams = Hh Mrs. Adams = Hh h = cystic fibrosis

Each child has a 25% of inheriting C.F.
Back The Adams Family Home So if we have a baby, what are the chances he/she would inherit cystic fibrosis? The gene that causes cystic fibrosis can be found on chromosome #7. Mr. and Mrs. Adams have tested to be heterozygous/carriers of cystic fibrosis. This means that each is healthy because they have a dominant healthy allele (H) on one of their chromosome #7s and a faulty recessive allele (h) on their other chromosome #7. Each child has a 25% of inheriting C.F. Look again Look again Look again Look again H h H H H H h 0% 25% 50% 75% 100% h H h h h H = healthy Mr. Adams = Hh Mrs. Adams = Hh h = cystic fibrosis

Back The Adams Family Home Can you predict the odds of having a baby that is heterozygous? Oh I get it. Our baby has a 50% chance of being heterozygous. The gene that causes cystic fibrosis can be found on chromosome #7. Mr. and Mrs. Adams have tested to be heterozygous/carriers of cystic fibrosis. This means that each is healthy because they have a dominant healthy allele (H) on one of their chromosome #7s and a faulty recessive allele (h) on their other chromosome #7. Look again Look again Look again Look again H h H H H H h 0% 25% 50% 75% 100% h H h h h H = healthy Mr. Adams = Hh Mrs. Adams = Hh h = cystic fibrosis

Click on the Punnett square that shows homozygous dominant.
Back The Adams Family Home Click on the Punnett square that shows homozygous dominant. The gene that causes cystic fibrosis can be found on chromosome #7. Mr. and Mrs. Adams have tested to be heterozygous/carriers of cystic fibrosis. This means that each is healthy because they have a dominant healthy allele (H) on one of their chromosome #7s and a faulty recessive allele (h) on their other chromosome #7. H h X correct H H H H h X X h H h h h H = healthy Mr. Adams = Hh Mrs. Adams = Hh h = cystic fibrosis

Back The Adams Family Home We were hoping to eventually have 3 children. What are the odds all three would have CF? The gene that causes cystic fibrosis can be found on chromosome #7. Mr. and Mrs. Adams have tested to be heterozygous/carriers of cystic fibrosis. This means that each is healthy because they have a dominant healthy allele (H) on one of their chromosome #7s and a faulty recessive allele (h) on their other chromosome #7. H h H H H H h h H h h h H = healthy Mr. Adams = Hh Mrs. Adams = Hh h = cystic fibrosis

Each has a ¼ chance of inheriting CF.
Back The Adams Family Home Each has a ¼ chance of inheriting CF. The gene that causes cystic fibrosis can be found on chromosome #7. Mr. and Mrs. Adams have tested to be heterozygous/carriers of cystic fibrosis. This means that each is healthy because they have a dominant healthy allele (H) on one of their chromosome #7s and a faulty recessive allele (h) on their other chromosome #7. 1 4 1 4 1 4 H h H H H H h h H h h h H = healthy Mr. Adams = Hh Mrs. Adams = Hh h = cystic fibrosis

Back The Adams Family Home To calculate the odds all three would inherit CF, just multiply ¼ x ¼ x ¼. The gene that causes cystic fibrosis can be found on chromosome #7. Mr. and Mrs. Adams have tested to be heterozygous/carriers of cystic fibrosis. This means that each is healthy because they have a dominant healthy allele (H) on one of their chromosome #7s and a faulty recessive allele (h) on their other chromosome #7. 1 4 1 4 1 4 H h H H H H h h H h h h H = healthy Mr. Adams = Hh Mrs. Adams = Hh h = cystic fibrosis

Back The Adams Family Home So there is a 1 in 64 chance that all three would inherit CF. Correct. The odds all three would inherit CF is very unlikely. The gene that causes cystic fibrosis can be found on chromosome #7. Mr. and Mrs. Adams have tested to be heterozygous/carriers of cystic fibrosis. This means that each is healthy because they have a dominant healthy allele (H) on one of their chromosome #7s and a faulty recessive allele (h) on their other chromosome #7. 1 4 1 4 1 4 H h H H H H h h H h h h H = healthy Mr. Adams = Hh Mrs. Adams = Hh h = cystic fibrosis

Back A Tough Decision Home You have a very important decision to make. Currently, sufferers of C.F. usually live to their early to mid-30s before they pass away. The disease causes too much damage to their lungs and heart. And they will require regular therapy throughout their lives so you will need to be prepared to help at any time. There are no mental problems associated with this disorder, only physical. But now that you know the risk, you must weigh the consequences before making your decisions to start a family of your own, adopt, or have no children at all. I wish you the best of luck. One more family to help

Back The Davis Family Home Mr. Davis suffers from sickle cell disease, which leaves him with shortness of breath and pain in his joints. Mrs. Davis is healthy, but she is a heterozygous/carrier of sickle cell disease because her mother passed the allele onto her. They are concerned about their future children.

Back The Davis Family Home Mr. Davis suffers from sickle cell disease, which leaves him with shortness of breath and pain in his joints. Mrs. Davis is healthy, but she is a heterozygous/carrier of sickle cell disease because her mother passed the allele onto her. They are concerned about their future children. Welcome Davis’. Let’s complete a Punnett square so we can get provide you information.

Back The Davis Family Home Sickle cell disease is just liked cystic fibrosis in that the gene is recessive. I’ll use “h” to represent the sickle cell allele. Mr. Davis suffers from sickle cell disease, which leaves him with shortness of breath and pain in his joints. Mrs. Davis is healthy, but she is a heterozygous/carrier of sickle cell disease because her mother passed the allele onto her. They are concerned about their future children. h = sickle cell disease

Back The Davis Family Home Mr. Davis suffers from sickle cell disease, which leaves him with shortness of breath and pain in his joints. Mrs. Davis is healthy, but she is a heterozygous/carrier of sickle cell disease because her mother passed the allele onto her. They are concerned about their future children. Healthy is the dominant allele, so I’ll use “H” to represent this allele. H = healthy h = sickle cell disease

Back The Davis Family Home Mr. Davis suffers from sickle cell disease, which leaves him with shortness of breath and pain in his joints. Mrs. Davis is healthy, but she is a heterozygous/carrier of sickle cell disease because her mother passed the allele onto her. They are concerned about their future children. Because Mr. Davis suffers from sickle cell disease, he must be homozygous recessive, hh. Mr. Davis = hh H = healthy h = sickle cell disease

We know that Mrs. Davis is healthy, but heterozygous “Hh”.
Back The Davis Family Home Mr. Davis suffers from sickle cell disease, which leaves him with shortness of breath and pain in his joints. Mrs. Davis is healthy, but she is a heterozygous/carrier of sickle cell disease because her mother passed the allele onto her. They are concerned about their future children. We know that Mrs. Davis is healthy, but heterozygous “Hh”. Mrs. Davis = Hh Mr. Davis = hh H = healthy h = sickle cell disease

Back The Davis Family Home Mr. Davis suffers from sickle cell disease, which leaves him with shortness of breath and pain in his joints. Mrs. Davis is healthy, but she is a heterozygous/carrier of sickle cell disease because her mother passed the allele onto her. They are concerned about their future children. So now we’ll place your genotypes on the outside of the Punnett square. Mrs. Davis = Hh Mr. Davis = hh H = healthy h = sickle cell disease

Back The Davis Family Home Mr. Davis suffers from sickle cell disease, which leaves him with shortness of breath and pain in his joints. Mrs. Davis is healthy, but she is a heterozygous/carrier of sickle cell disease because her mother passed the allele onto her. They are concerned about their future children. H h h Mrs. Davis = Hh Mr. Davis = hh H = healthy h = sickle cell disease

Now we just fill in the inner Punnett squares.
Back The Davis Family Home Mr. Davis suffers from sickle cell disease, which leaves him with shortness of breath and pain in his joints. Mrs. Davis is healthy, but she is a heterozygous/carrier of sickle cell disease because her mother passed the allele onto her. They are concerned about their future children. Now we just fill in the inner Punnett squares. H h h Mrs. Davis = Hh Mr. Davis = hh H = healthy h = sickle cell disease

The Davis Family H h h H h h h H h h h
Back The Davis Family Home Mr. Davis suffers from sickle cell disease, which leaves him with shortness of breath and pain in his joints. Mrs. Davis is healthy, but she is a heterozygous/carrier of sickle cell disease because her mother passed the allele onto her. They are concerned about their future children. H h h H h h h H h h h Mrs. Davis = Hh Mr. Davis = hh H = healthy h = sickle cell disease

Back The Davis Family Home You’re child has a 50% chance of being healthy. If we have a child, what are the chances he/she would be healthy? Mr. Davis suffers from sickle cell disease, which leaves him with shortness of breath and pain in his joints. Mrs. Davis is healthy, but she is a heterozygous/carrier of sickle cell disease because her mother passed the allele onto her. They are concerned about their future children. H h Look again Look again Look again Look again 0% 25% 50% 75% 100% Mrs. Davis = Hh Mr. Davis = hh H = healthy h = sickle cell disease

Back The Davis Family Home Mr. Davis suffers from sickle cell disease, which leaves him with shortness of breath and pain in his joints. Mrs. Davis is healthy, but she is a heterozygous/carrier of sickle cell disease because her mother passed the allele onto her. They are concerned about their future children. What are the chances your child could be homozygous dominant? Since I have the disease, 0% of my kids would be “HH”. H h Look again Look again Look again Look again 0% 25% 50% 75% 100% Mrs. Davis = Hh Mr. Davis = hh H = healthy h = sickle cell disease

Another Tough Decision
Back Another Tough Decision Home You need to know that every child you have together will have a 50% chance of inheriting sickle cell disease. Life expectancy reporting an average of 42 and 48 years for males and females, respectively. You need to know these facts before you decide how to proceed with your family. I wish you the best of luck if you decide to start a family.

Back Remembering Mendel Home Between 1856 and 1863 Mendel cultivated and tested some 29,000 pea plants. Mendel died on January 6, 1884, at age 61, in Brünn, Austria-Hungary (now Brno, Czech Republic). The significance of Mendel's work was not recognized until the turn of the 20th century. Its rediscovery prompted the foundation of the discipline of genetics. Wow! I can’t believe my work is helping people make decisions about the heath of their children. Science is amazing!

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Genetics Tutorial Place your keyboard aside. Only use the mouse.

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