X linked traits and recombination

Question 1

What are sex linked traits?

Answer 1

Genes that are on the sex chromosomes (X or Y)
Their inheritance patterns differ between males (XY) and females (XX)

Question 2

How are sex linked traits inherited?

Answer 2

Sex-linked diseases are inherited through one of the sex chromosomes. Dominant inheritance occurs when an abnormal gene from one parent can cause a disease, even though a matching gene from the other parent is normal

Question 3

How many genes are there in humans?

Answer 3

Around 20,000

Question 4

How are linked genes inherited?

Answer 4

Linked genes show biases towards parental genotypes

Question 5

How can we determine the order and location of genes within a chromosome?

Answer 5

By using recombination frequencies

Question 6

How does the distance between two genes affect recombination frequency?

Answer 6

Distant (unlinked) genes have recombination frequencies around 50%
Close genes have recombination frequencies of 0-50%
There is a near linear relationship between distance and recombination frequency

Question 7

What is an X-linked dominant disease?

Answer 7

Disease that is observed in every generation, affected mothers will produce 50% affected offspring, affected fathers will produce 100% affected daughters and no affected sons

Question 8

What are Y linked diseases?

Answer 8

VERY RARE, Transmitted male to male, all sons will be affected no daughters (females cannot posses Y allele)