L3 - mendelian genetics 2

Question 1

what can be the cause of deviations from mendelian inheritance?
(not 3:1 or 9:3:3:1 ratios)

Answer 1

1. non independent assortment - eg gene linkage on chromosomes
2. non mendelian segregation of phenotypes - eg complex gene interactions

Question 2

why do we use chi squared test in mendelian genetics?

Answer 2

to test whether deviations from mendelian ratios are down to chance

Question 3

if the difference between E and O is very big, what does this indicate?

Answer 3

difference not due to chance

due to linkage or something etc

Question 4

if the difference between E and O is very small, what does this indicate?

Answer 4

difference is due to chance

Question 5

why is it more difficult to study inheritance in humans

Answer 5

1. cant control mating
2. can only look at available families
3. less offspring

Question 6

what is pedigree analysis

Answer 6

looking at family trees for inheritance patterns

Question 7

what are the signs of autosomal recessive inheritance in a pedigree

Answer 7

1. disease appears in offspring of unaffected parents
2. can affect M/F (not sex linked)
3. consanguineous parents (who are related) more likely to produce affected offspring

Question 8

what does consanguineous parents mean?

Answer 8

parents that are related

Question 9

what are the signs of dominant autosomal inheritance in a pedigree

Answer 9

1. disease is in every generation after first appearance

2. affected progeny M/F (not sex linked)

Question 10

what are the signs in a pedigree that a disease is not sex lined

Answer 10

M and F affected equally