linkage and unlinkage

Question 1

what is an autosomal linkage

Answer 1

Anautosomeis a chromosome that is not a sex chromosome

The two genes are linked (found) on the same chromosome

Question 2

what can gene linkage lead to

Answer 2

Gene linkage can produce very different observed ratios!!!

Genes can be linked on autosomes or sex chromosomes

Question 3

what type of combination can each gamete have of alleles

Answer 3

Each gamete can have any combination of dominant/recessive alleles = 4 different gametes

Question 4

how many chromosomes cane ach gamete have

Answer 4

Each gamete can only have one chromosome, so there are only 2 different gametes

Question 5

what does crossing over allow

Answer 5

This allows for a small number of new combinations

Question 6

what is crossing over

Answer 6

Homologous pairs of chromosomes associate / form a bivalent;

Chiasma(ta) form;

(Equal) lengths of (non-sister) chromatids / alleles are exchanged;

Producing new combinations of alleles;

Question 7

what are the rules of linkage

Answer 7

The closer together two genes are on an autosome, the more closely-linked they are (less likely to become separated by crossing over)

The nearer a gene is to the end of the autosome, the more likely they are to undergo crossing over

Question 8

give two reasons why the observed frequency may be similar but not the same as the expected frequency

Answer 8

small sample size

chance

random fertilisation