3.7.1.3 Linkage

Question 1

What is linkage?

Answer 1

2 genes on the same chromosome

Question 2

Autosomal linkage

Answer 2

gene not on sex chromosomes

Question 3

Sex linkage

Answer 3

gene is on sex chromosomes (X or Y)

Question 4

How do chromosomes appear after DNA replication (specific wording only)

Answer 4

chromosomes appear as sister chromatids held together with a centromere

Question 5

How are linked genes passed to offspring and why?

Answer 5

linked genes are passed to offspring together because they will stay together during independent segregation in meiosis 1

Question 6

what will the gametes of linked genes generally be?

Answer 6

AB or ab (dominants together, recessive together)

Question 7

How do less common gametes occur (in linked genes) and what are they?

Answer 7

Ab or aB (also known as recombinants)

Occur due to crossing over during prophase 1

Question 8

What affects how likely genes on an autosome will be split up during crossing over?

Answer 8

the closer together two genes are, the more closely linked they are and are less likely to be split up

Question 9

What is the expected phenotype ratio from a heterozygous unlinked dihybrid cross?

Answer 9

9:3:3:1

Question 10

What is the expected phenotype ratio from a heterozygous linked dihybrid cross?

Answer 10

3:1

Question 11

What is the impact of the Y chromosome being smaller than X

Answer 11

Carries fewer genes

Question 12

What & who is a carrier?

Answer 12

females heterozygous for recessive conditions

Question 13

How many alleles to males need for a trait to be expressed?

Answer 13

1