# BIO2008: Lecture 2

0.0 / 5

HideShow resource information

- Created by: LMoney
- Created on: 10-05-14 18:42

what is the probability of an allele equal to?

its frequency

1 of 31

what does Mendel's law state?

Segregation of alleles of a gene in formation of reproductive cells

2 of 31

How can you test whether genotypic ratios in offspring follow Mendelian inheritance?

Chi-squared test (X^2 test)- in this case Chi-squared goodness of fit because testing against distribution

3 of 31

what are the other Chi-squared tests?

Chi squared test of association, Chi squared test of homogeneity

4 of 31

should frequencies or number be used in chi-squared tests?

always numbers

5 of 31

A dominant over a. In offspring of a Aa x Aa cross what is the probability of phenotype A?

75%

6 of 31

what is the most common mode of variation at the DNA level?

mostly codominant

7 of 31

what are the most widely used molecular markers in population genetics?

allozymes (isozymes, protein variants)

8 of 31

which DNA based methods are used in population genetics?

1) RFLP analysis 2) PCR 3) sequencing

9 of 31

how is Allozyme or DNA analysis carried out?

Run an extract/PCR product of individuals on a gel: separate molecules on charge- measure differences in velocity in the gel

10 of 31

what is the Hardy Weinburg principle used for?

calculate expected genotype frequencies under 'random' mating in 'ideal' population

11 of 31

what is an ideal population?

diploid, sexual reproduction, nonoverlapping, generations, large populations, no effect of natural selection etc.

12 of 31

Let p be the allele frequency of A and q the allele frequency of a, what are the frequencies for the genotypes?

p^2 for AA, 2pq for Aa, q^2 for aa

13 of 31

What is the maximum frequency of heterozygotes in a population? (according to Hardy Weinburg)

50%

14 of 31

what is the test for presence of HW equilibrium?

Chi squared goodness of fit test

15 of 31

what does the Chi squared goodness of fit test do, in this context?

Tests whether there is a significant difference between genotype numbers observed and genotype numbers expected under HW

16 of 31

how many degrees of freedom is there for 3 genotypic classes?

1

17 of 31

If the calculated chi-square value is less than the 0 .05 value in the table, what do we do with the hypothesis?

we accept it, if it was greater- accept it- if we accept, means the population is in HW equilibrium

18 of 31

when can examples of the HW principle become more complicated?

1) If sex-linked (gene is on X chromosome) 2) If dominant/recessive alleles 3) If more than two alleles 4) If you have polyploids (too complicated)

19 of 31

when can deviations from HW happen?

1) Inbreeding 2) Population structure 3) Mate choice 4) Selection against/for certain genotype

20 of 31

when does inbreeding happen?

1) Plants that self-fertilise 2) Mating between related individuals

21 of 31

what happens to the genotype frequencies with inbreeding?

Excess homozygote genotypes relative to the frequencies expected with random mating

22 of 31

what halves number of heterozygotes every generation?

self-fertilisation

23 of 31

what lowers proportion heterozygotes in subpopulations, relative to expected?

structure

24 of 31

what is assortative mating, or positive assortative mating?

similar individuals mate more often than expected under random mating

25 of 31

what is disassortative mating or negative assortative mating?

dissimilar individuals mate more often than expected under random mating

26 of 31

What do you predict with assortative mating?

Less heterozygotes than in HW (deficit)

27 of 31

what is an example of assertive mating?

flowering time differences

28 of 31

what are examples of disassortive mating?

SI system in plants, MHC in mammals

29 of 31

selection with heterozygote advantage you predict to find what?

More heterozygotes than expected

30 of 31

with Hybridisation, often heterozygotes less fit so you would predict to find what?

Deficit heterozygotes, less

31 of 31

## Other cards in this set

### Card 2

#### Front

what does Mendel's law state?

#### Back

Segregation of alleles of a gene in formation of reproductive cells

### Card 3

#### Front

How can you test whether genotypic ratios in offspring follow Mendelian inheritance?

#### Back

### Card 4

#### Front

what are the other Chi-squared tests?

#### Back

### Card 5

#### Front

should frequencies or number be used in chi-squared tests?

#### Back

## Similar Biology resources:

0.0 / 5

0.0 / 5

0.0 / 5

5.0 / 5

0.0 / 5

0.0 / 5

## Comments

No comments have yet been made