Lecture 8/9

Question 1

Linkage

Answer 1

2 or more genes on the same chromosome

Question 2

For discovering if genes are linked, Look at Chi Square math for expected mendelian (25%) and observed frequencies (given)

Answer 2

There are some good slides around slide 18-19 in lecture 8, also recommend watching videos

Question 3

Recombination for coupling or Cis configuration

Answer 3

Wild together on the same chromosome (or non wild) (A+ W+)

Question 4

Recombination for trans or repulsion

Answer 4

Wild with a non wild on the same chromosome (A+ W)

Question 5

What is a centimorgan / map unit

Answer 5

Frequency of recombination, 1% recombination = 1 MU or CM

Question 6

How to calculate MU

Answer 6

Once you have identified the parents in a test cross (Often the observed with larger number) - add up the recombinants. Divide the recombinants by the total number of offspring. See Slide 29 in Lecture 8

Question 7

Why can recombination not exceed 50%

Answer 7

because 50% means that the genes are functionally unlinked

Question 8

How to determine order of 3 linked genes

Answer 8

Find the double cross over events, then find the gene that doesnt share the original parent configuration, and put it in the middle (See page 50 of lecture 8)

Question 9

Calculate Map Distance for 3 linked genes

Answer 9

recombinants of a and b /total x 100 = MU then recombinants of b and c /total x 100 = MU, then add the two together. (Slide 51 of lecture 8)

Question 10

Note that lecture 9 covers this information too, goes into greater detail on 3 gene linkage

Answer 10

GOOD LUCK