Mendel and Mastering Punnett Squares

BILL Question for Table Groups Explain the laws of segregation and independent assortment using the following homologous chromosomes. Show what can happen to the four alleles during meiosis (ignore crossing over).

BILL: Which of Mendel’s Laws is shown? Explain how you know. Segregation: only one gene is shown

BILL: List similarities and differences between the Law of Independent Assortment and the Law of Segregation.

SIMILARITIES: •Occur during meiosis. •Both involve a separation of alleles. DIFFERENCES: •Segregation: Alleles for the SAME gene (like height) separate (segregate ) into different gametes –If a male is heterozygous (Tt), ½ of his sperm gets a "t" and the other ½ gets a "T” •Independent Assortment: Alleles for DIFFERENT gene separate (in this case we say assort) independently from each other. –How alleles move for the height gene has no impact on how alleles move for the tongue rolling gene.

PUNNET PRACTICE EXPECTATIONS 1.Determine gene, alleles and parental 2n genotypes from problem. EXAMPLE: Cross a heterozygous tall plant with a short plant. Gene: section of DNA that codes for a protein that controls the height of plant Alleles: slightly different versions of the gene ( different proteins) that code for either tall (T) or short (t) phenotypes P1 genotype: Tt (heterozygous) P2 genotype: tt (homozygous recessive)

PUNNET PRACTICE EXPECTATIONS 2. Draw the parental chromosomes in germ cells as they would appear in G1. EXAMPLE:

PUNNET PRACTICE EXPECTATIONS 3.Determine the unique gametes possible from each parent

PUNNET PRACTICE EXPECTATIONS Draw a Punnett Square using unique gametes only

PUNNET PRACTICE EXPECTATIONS Fill in the Punnet Square with the possible genotypes of the offspring.

PUNNET PRACTICE EXPECTATIONS Summarize possible genotypes and phenotypes of offspring, with expected ratios EXAMPLE: ½ Tt  Tall ½ tt Short

PUNNET PRACTICE EXPECTATIONS Celebrate and feel proud EXAMPLE: “Wow, this is fun. I love learning.” “I’m awesome for getting this.” “Way to go, me!” “I am a Punnet master.”

PUNNET PRACTICE EXPECTATIONS 1.Determine gene, alleles and parental 2n genotypes 2.Draw the parental chromosomes in G1 germ cells 3.Draw the gamete cells at the end of meiosis 4.Determine the unique gametes from each parent 5.Draw a Punnett Square using unique gametes only 6.Fill in the Punnet Square with the possible genotypes of the offspring. 7.Summarize possible genotypes and phenotypes of offspring, with expected ratios 8.Celebrate and feel proud