Mendelian Genetics What we learned Mendels contributions Mendelian
Mendelian Genetics: What we learned? Mendel’s contributions?
Mendelian Genetics: What we learned? How many traits are considered for Aa. Bb. Cc
Mendelian Genetics: What we learned? How many genotypic different gametes are produced by Aa. Bb. Cc?
Mendelian Genetics: What we learned? What are the gametes produced by Aa. Bb?
Mendelian Genetics: What we learned? What cross yields A-: aa 1: 1? What cross yields A-: aa 3: 1? What cross yields A-: aa 0: 1?
Mendelian Genetics: What we learned? When are there only two phenotypes among the offspring?
A cross yields a corn cob with 705 blue and 224 yellow kernels (blue>yellow). What is the genotype of the parents? (Or, what cross yielded these results? )
For a single-trait cross with dominant-recessive relationship between A and a:
Consider monohybrid cross: Trait blue yellow total Expected Observed
Consider test cross: Trait blue yellow total Expected Observed
How do we evaluate difference between expected and observed? Trait Expected Observed blue 3 1500 yellow 1 500 total 4 2000
How do we evaluate difference between expected and observed? Trait Expected Observed blue 1 465 705 yellow 1 464 224 total 2 929
Expectations and observations may differ for two reasons: 1 st. Happy accidents.
Expectations and observations may differ for two reasons: 1 st. Happy accidents.
Expectations and observations may differ for two reasons: 2 nd The model is wrong.
Expectations and observations may differ for two reasons: 2 nd The model is wrong.
Calculate Chi-square:
Calculate Chi-square: Example: Trait Blue yellow Total Expected 697 232 929 Observed 705 224 929
Calculate Chi-square: Example: Trait Blue yellow Total Expected 465 464 929 Observed 705 224 929
Calculate Chi-square: Example: Trait Red Pink White Expected Observed 225 400 215
Calculate Chi-square: Example: Trait Red Pink White Expected Observed 225 400 215
Calculate df = (n-1):
Determine probability, P, for obtaining such a chi -square by chance alone:
Determine probability, P, for obtaining such a chi -square by chance alone: When difference is small: When difference is large:
Determine probability, P, for obtaining such a chi -square by chance alone: Example: chi-square: 0. 366 (df = 1)
Determine probability, P, for obtaining such a chi -square by chance alone: Example: chi-square: 248 (df = 1)
Determine probability, P, for obtaining such a chi -square by chance alone: Example: chi-square: 2. 14 (df = 2)
- Slides: 28