Mendel’s Work Gregor Mendel was a priest in the 19 th century who loved to garden. While tending his garden he wondered why some plants had traits similar to their parents, and some plants had different traits then those of their parents. TRAIT: Each different form of a characteristic that an organism can pass on to it’s offspring.

Mendel’s Work Mendel decided to study heredity. His research would eventually earn him the nick name “the father of genetics”. HEREDITY: the passing of physical characteristics from parent to offspring. GENETICS: the scientific study of heredity.

Mendel’s Experiment Mendel started his experiments with purebred plants. PUREBRED: an organism that is the offspring of many generations that have the same trait. (purebred short pea plants come from short parents and short grandparents, and short great grandparents) – It can be represented by letters TT or pp (all caps or all lowercase)

Mendel’s Experiment Once Mendel had purebred plants, he cross bred plants with different traits with one another.

Mendel’s Experiment In Mendel’s experiments, he called plants in the first cross the parental generation or P generation. The offspring of the P genertation he called the F 1 generation. The offspring of the F 1 generation he called the F 2 generation.

Mendel’s Results P = Parent Generation F = Daughter or Son 1 st Generation F = Daughter or Son 2 nd Generation

Mendel’s Results In all of Mendel’s crosses only one form of the trait appeared in the F 1 generation, however, in the F 2 generation the lost form of the trait always reappeared in about ¼ of the plants.

Dominant and Recessive Alleles GENE: A section of the DNA that codes for a specific trait. (hair color gene) ALLELES: the different forms of a particular gene. (brown or blonde) An organisms traits are controlled by the alleles it inherits from it’s parents. Some alleles are dominant while other alleles are recessive.

These are alleles; different forms of a gene cc – could be alleles for hair color ee- could be alleles for spots hH- could be alleles for straight hair

Dominant and Recessive Alleles

A dominant allele is one whose trait always shows up in the organism when the allele is present. Represented by a Capital Letter(T) A recessive allele is one whose trait is hidden when the dominant allele is present. Represented by a Lower Cased Letter(t)

Inheriting Alleles and Symbols for Alleles (Purebred vs. Hybrid) For every trait you have, your DNA is carrying 2 alleles. One came from your mom and one came from your dad. If both are the dominant version, you show the dominant trait. Ex. TT (purebred) If both are the recessive version, you show the recessive trait. Ex. tt (Purebred) If one is the dominant version and one is the recessive version, you show the dominant trait. Ex. Tt (Hybrid)

Inheriting Alleles and Symbols for Alleles (Purebred vs. Hybrid) Hybrid - Tall Purebred - Short Purebred - Tall In hybrid allele combinations; if the dominant allele is present then that trait will appear. Recessive traits only appear if both recessive alleles are present.

Phenotypes and Genotypes An organism’s phenotype is its physical appearance or visible traits. (tall, blonde, round seeds, brown eyes) An organism’s genotype is its genetic makeup or allele combinations. (Tt, bb, RR, Bb)

Genotypes An organism that has two identical alleles for a trait is said to be homozygous. RR= homozygous dominant rr= homozygous recessive An organism that has two different alleles for a trait is said to be heterozygous. Rr = heterozygous

Mitosis – Two Colored Pencils Interphase Prophase Metaphase Anaphase Telophase/Cytokinesis Diploid Chromosomes – 23 pairs (46 Chromosomes)

Meiosis – Diploid Cell to Haploid Interphase Prophase Metaphase Anaphase Telophase

Section 3 The Cell and Inheritance According to the chromosome theory of inheritance, genes are carried from their parents to their offspring on chromosomes.

The Cell and Inheritance Remember, humans have 46 chromosomes. Those chromosomes are in pairs. 23 come from the father’s sperm, and 23 come from the mother’s egg. When the sperm and egg come together, the resulting offspring has all 46 chromosomes.

23 pairs of chromosomes (single copy of the DNA) 23 pairs of chromosomes (duplicated DNA) Chromosomes in the same pair carry the same genes, but not necessarily the same alleles. For example, pair #1 may have the mother’s hair color gene on one chromosome, and the father’s hair color gene on the other chromosome. xx

Meiosis How do sperm and eggs end up with only half the number of chromosomes? Instead of dividing by MITOSIS, the parent cells of sperm and eggs divide by a process called meiosis.

Meiosis During meiosis the chromosomes pairs separate and are distributed to two different cells. The resulting cells have only half as many chromosomes as the other cells in the organism.

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Meiosis When the chromosomes pairs separate and go into two different sex cells, so do the alleles carried on each chromosome. One allele from each pair goes to each sex cell.

Gene for eye color from the mother (green allele) Gene for eye color from the father (brown allele) Sperm This is a cell in a male’s reproductive system. Like other cells, it has 46 chromosomes, one set of 23 from it’s mother, and one set of 23 from it’s father. This cell will go through meiosis to produce sperm. After Meiosis, each sperm only carries one of the two possible alleles from the male organism.

Gene for eye color from the mother (green allele) Gene for eye color from the father (brown allele) Sperm The parent organism has two alleles for the eye color gene, green or brown. The sex cells only carry one allele for eye color.

Gene for eye color from the mother (green allele) Gene for eye color from the father (brown allele) Sperm When one of these sperm comes together with an egg, the offspring will inherit one allele for eye color from their father.

Meiosis accounts for probability S = Round Pea s = Wrinkled pea Ss = Round

Mitosis and Meiosis

Please Take out your Foldable Put these Terms on the Back Side of your foldbable – Probability = chance an event will occur – Independence of Events = chances of one event do not effect the outcome of the next event – Punnett Squares = shows combinations of allele possibilities – Phenotype = physical characteristic – Genotype = allele combination (Tt, Bb, hh, FF) – Homozygous = TT (Dominant;purebred) tt(recessive; purebred) – Heterozygous = Tt (hybrid)

Mendel’s Results P = Parent Generation F = Daughter or Son 1 st Generation F = Daughter or Son 2 nd Generation

Dominant and Recessive Alleles

A dominant allele is one whose trait always shows up in the organism when the allele is present. Represented by a Capital Letter(T) A recessive allele is one whose trait is hidden when the dominant allele is present. Represented by a Lower Cased Letter(t)

Inheriting Alleles and Symbols for Alleles (Purebred vs. Hybrid) For every trait you have, your DNA is carrying 2 alleles. One came from your mom and one came from your dad. If both are the dominant version, you show the dominant trait. Ex. TT (purebred) If both are the recessive version, you show the recessive trait. Ex. tt (Purebred) If one is the dominant version and one is the recessive version, you show the dominant trait. Ex. Tt (Hybrid)

Inheriting Alleles and Symbols for Alleles (Purebred vs. Hybrid) Hybrid - Tall Purebred - Short Purebred - Tall In hybrid allele combinations; if the dominant allele is present then that trait will appear. Recessive traits only appear if both recessive alleles are present.

DO NOW PLEASE FINISH FOLDABLE AT HOME – USE MY ANSWERS Take out your foldable and glue the vocab onto the back side of the last page

Section 2 Probability and Heredity Probability is a number that describes how likely it is that an event will occur.

Probability Probability can be expressed as a fraction, or as a percent. If you flip a coin, there is a one in two chance it will land on heads…. ½, or 50% If you roll a dice, there is a one in six chance you will roll a 5… 1/6, or about 17%.

The Coins 1 coin represents alleles from MOM – Mom is heterozygous purple or Pp – Heads = P – Tails = p 1 coin represents alleles from DAD – Mom is heterozygous purple or Pp – Heads = P – Tails = p

The Coins in terms of Alleles DadMom

Meiosis

COIN TOSS LAB PpPp PpPp

Math GenotypesExpected ProbabilityTallyActual Probability PP (homozygous/ purbred dominant) Pp (heterozygous/ hybrid) pp (homozygous/ Purbred recessive

Finding Percentage

Independence of Events When you toss a coin more than once, the results of one toss do not affect the results of the next toss. Flipping a heads the first time, does not make you more likely to flip a tails the next time.

Probability and Genetics Mendel realized that when he crossed tall plant and a short plant, the probability of the off spring in the F 1 generation being tall was 4/4 or 100% The probability of the offspring in the F 2 generation being tall was ¾ or 75%

Punnett Squares A punnett square is a chart that shows all possible combinations of alleles that can result from a genetic cross.

Punnett Squares Capital letters= Dominant allele Lowercase letters= recessive allele Ex. The allele for round seed is dominant over the allele for wrinkled seeds R=round seeds r = wrinkled seeds

T = Tall t = short COMPLETE THESE IN YOUR NOTEBOOK

T = Tall t = short

Please Take out your Foldable Put these Terms on the Back Side of your foldbable – Probability = – Independence of Events = – Punnett Squares = – Phenotype = – Genotype = – Homozygous = – Heterozygous =

Meiosis accounts for probability S = Round Pea s = Wrinkled pea Ss = Round

Words to Know Homozygous – combination of alleles in which both are the same; both dominant (TT) or both recessive (tt) – also known as purebred Heterozygous – a combination of alleles in which both are different or hybrid; dominant and recessive (Tt) - also known as hybrid Phenotype – the actual physical appearance; tall, short, brown eyes, blue eyes, based on the genotype Genotype – the combination of alleles (TT, Tt, tt); these combinations Dominant – Alleles that are dominant are represented by a capital letter (“T”) and will always appear (in the phenotype) if they are present Recessive – Alleles that recessive are represented by a lower cased letter (“t”) and will be masked if a dominant alleles is present