Table of Contents Chapter Preview 5.1 Mendel’s Work 5.2 Probability and Heredity 5.3 The Cell and Inheritance 5.4 Genes, DNA, and Proteins

How are traits passed from parents to offspring? In a litter of puppies, some of the puppies have a black and white coat, and others have a red and white coat. What can you infer about how their parents look? What can you infer about the parents’ DNA?

Section 1: Mendel’s Work What were the results of Mendel’s experiments, or crosses? What controls the inheritance of traits in organisms?

Crossing Pea Plants Gregor Mendel self-pollinated or cross-pollinated plants- contains both male (pollen) and female (pistil) reproductive structures. Pollen from one flower can fertilize the same flower or another flower on the same plant.

Mendel’s Experiments In all of Mendel’s crosses, only one form of the trait appeared in the F1 (first) generation. However, in the F2 (second) generation, the “lost” form of the trait always reappeared in about one fourth of the plants.

He noticed that ONE trait always appeared…and the other seemed to vanish. He called the trait that appeared most often the DOMINANT TRAIT (STRONG) He called the trait that seemed to only appear occasionally the RECESSIVE TRAIT (whimpy).

Why don’t you look like a Rhino? Well….neither of your parents are rhinos. And…because of HEREDITY or the passing of traits from parents to offspring.

Is a form of a GENE…….it is either dominant or recessive. ALLELE Is a form of a GENE…….it is either dominant or recessive. Purebred- 2 of the same alleles passed on from generation to generation. Hybrid- 2 different alleles from the same trait.

C. some purple and some white flowers D. all light-purple flowers What do you think??? If a pea plant that is purebred purple flowers is crossed with a pea plant that has white flowers, what do you think the offspring will look like? A. all purple flowers B. all white flowers C. some purple and some white flowers D. all light-purple flowers

And The Answer Is…. PP for Purebred Purple flowers pp for white flowers ONLY POSSIBILITIES….. Pp So therefore all flowers will be purple

Summary for CN The results of Mendel’s experiments were______________. (Go back and find 2 support statements from your notes here:) For example,____________________. Equally important (or transition word of your choice),________________________ ___________ controls the inheritance of traits in organisms. Go back and find 2 support statements from your notes here:) To begin with,______________________. Furthermore,_______________________.

Check yourself!!! 1. What color will the offspring be when a YY pea is bred with a yy pea? ____________________________________________________________ 2. What color will the offspring be when a Yy pea is bred with a yy pea? 3. If a YY pea is bred with a YY pea, how many green peas will result in the next three generations? ____________________________________________________ 4. If an rR pea is bred with an Rr pea, will the offspring be smooth or wrinkled or both? _____________________________________________________________ 5. If an rr pea is bred with an RR pea, will the offspring be smooth or wrinkled or both? 6. What kind of pea will result if an RR YY pea is bred with itself? 7. Is green a dominant or recessive trait? 8. Is smoothness a dominant or recessive trait?

End of Section: Mendel’s Work

Section 2: Probability and Heredity What is probability and how does it help explain the results of genetic crosses? What is meant by genotype and phenotype? What is codominance?

Percentages One way you can express a probability is as a percentage. A percentage (%) is a number compared to 100. For example, 50% means 50 out of 100. Suppose that 3 out of 5 tossed coins landed with heads up. Here’s how you can calculate what percent of the coins landed with heads up. Write the comparison as a fraction. 3 out of 5 = 3/5 2. Multiply the fraction by 100% to express it as a percentage. 3/5 x 100%/1 = 60%

Percentages Practice Problem Suppose 3 out of 12 coins landed with tails up. How can you express this as a percent? 25%

Chromosomes and Heredity Chromosomes are located on DNA and contain the necessary information (traits/ genes) which is passed on from your parents.

DOMINANT is written in CAPITAL LETTERS. (DD) Punnett Squares Tool used to show all possible combinations of alleles from parents. 2 forms of a gene: DOMINANT is written in CAPITAL LETTERS. (DD) Recessive is written in lowercase letters. (dd)

Heterozygous genes- Different alleles (Dd) Homozygous genes- Same alleles (DD, dd)

Probability and Genetics In a genetic cross, the allele that each parent will pass on to its offspring is based on probability.

DAD You get 2 alleles: 1 from each parent MOM

A Punnett Square The diagrams show how to make a Punnett square. In this cross, both parents are heterozygous for the trait of seed shape. R represents the dominant round allele, and r represents the recessive wrinkled allele.

How Do You Make A Punnett Square???? Lets make one to figure out if you will have hair on your big toe. First:                                          

HAIRY TOES are DOMINANT (HH) Your Dad has these.. Non-hairy toes are NEXT : HAIRY TOES are DOMINANT (HH) Your Dad has these.. Non-hairy toes are Recessive (hh) Your Mom has none.

H H h Hh Hh h Hh Hh

2. H is DOMINANT for hairy big toes. Therefore…. 1. We ended up with 4 Hh 2. H is DOMINANT for hairy big toes. 3. So there is a 100% chance you will end up with HAIRY TOES. 4. Even if you have the DOMINANT H with the recessive h, the DOMINANT beats out the recessive!!! You still have hairy toes…

Big Hairy Toes…..or not? Based on our results- the Genotype is 100% Hh and the Phenotype is 100% hairy big toes!!!!

Phenotypes and Genotypes An organism’s phenotype is its physical appearance, or visible traits. An organism’s genotype is its genetic makeup, or allele combinations (letters).

YOU TRY ONE……. 1. Make a Punnett Square first…. 2. For rabbits, the allele for black fur, B is DOMINANT over the allele for white fur, b (recessive). 3. Suppose both parents have the genotypes- Bb-, what are the parent’s phenotypes and what are their baby’s genotype and phenotypes?

PARENTS PHENOTYPE IS BLACK!!!! Genotypes (letters) 1 BB- 25% 2 Bb- 50 % 1 bb- 25% Bb B BB Phenotypes (appearance) 3 black- 75% 1 white- 25% b Bb bb

Codominance In codominance, the alleles are neither dominant nor recessive. As a result, both alleles are expressed in the offspring.

Links on Probability and Genetics PHSchool.com Enter Code: scn-0332 Click the SciLinks button for links on probability and genetics.

Section 3: The Cell and Inheritance What role do chromosomes play in inheritance? What events occur during meiosis? What is the relationship between chromosomes and genes?

Meiosis vocabulary Sperm: male reproductive cell Egg: female reproductive cell Gamete: reproductive cell Meiosis: type of cell division that produces gamates.

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

Punnett Square A Punnett square is actually a way to show the events that occur at meiosis.

A Lineup of Genes Chromosomes are made up of many genes joined together like beads on a string. The chromosomes in a pair may have different alleles for some genes and the same allele for others.

Draw a chromosome… Chromosome Centromere Genes DNA ladder

Links on Meiosis PHSchool.com Enter Code: scn-0333 Click the SciLinks button for links on meiosis.

End of Section: The Cell and Inheritance

Section 4: Genes, DNA, and Proteins What forms the genetic code? How does a cell produce proteins? How can mutations affect an organism?

The DNA Code Chromosomes are made of DNA. Each chromosome contains thousands of genes. The sequence of bases in a gene forms a code that tells the cell what protein to produce.

How Cells Make Proteins During protein synthesis, the cell uses information from a gene on a chromosome to produce a specific protein.

Mutations Mutations can cause a cell to produce an incorrect protein during protein synthesis. As a result, the organism’s trait, or phenotype, may be different from what it normally would have been.

Can you spot the mutation?

Protein Synthesis Activity PHSchool.com Code: cep-3034 Click the Active Art button to open a browser window and access Active Art about protein synthesis.