Monday, February 25, 2013. Take a penny lab and staple it Take a “ How to Solve a Basic…. ” handout Turn in Meiosis Lab onto Computer cart. Genotype Phenotype Homozygous Heterozygous Allele. Gregor Mendel : ‘ father ’ of modern genetics.
If alleles for a trait are different (Rr) then 50% chance of gametes (1/2) receive one allele (R) & 50% receive the other allele (r)
it can be assumed (unless otherwise stated) that each allele (letter) is on a separate chromosome
-->So how many chromosomes are represented by the genotype above?
-->How many possible gametes are created from the genotype above? (HINT: each trait is on a separate chromosome so apply law of independent assortment!)
--> How many possible offspring genotypes exist if both parents have the genotype above?
Trait = Seed shape
Phenotypes: Round seeds or Wrinkled seeds
Genotypes: = AA, Aa, aa
Homozygous = AA or aa
Homozygous Dominant = AA
Homozygous Recessive = aa
Heterozygous (hybrid) = Aa
Genotypic Ratio: 1AA : 2 Aa : 1aa
Phenotypic Ratio: 3 Round : 1 Wrinkled
Probability = chance event will occur
total # of possible events
“AND” Rule: Rule of Multiplication
For two or more separate events occurring at the same time (or in succession), multiply the individual probabilities of events together
EX 1: If parents are BB and Bb, what is chance of B gamete & b gamete combining to form zygote?
1/1 B and 1/2 b = 1/1 * 1/2 = 1/2 chance of Bb zygote
EX 2: Parent genotype is AaBBDdEe:
What is probability of gamete with genotype of ABdE?
1/2 * 1* 1/2 * 1/2 = 1/8 chance of ABdE
A pedigree is a family history showing inheritance of a particular trait through familial generations
Karyotypes are photographs of stained, human chromosomes present at metaphase of mitosis. Karyotypes are used to determine if chromosomes are defective and help to diagnose chromosomal disorders such as Down’s Syndrome.
Is this a boy or girl’s karyotype?
Non-disjunction of sister chromatids during meiosis II