Lecture 12 Flashcards
1
Q
What did TH Morgan do
A
crossed wild type fly with a purple wide eyed fly – 2 parental and 2 recombinant
2
Q
How do you work out linkage
A
working out a percentage of recombinance – the greater the recombinance the greater the distance of the genes
3
Q
3 point crosses
A
3 point crosses when 3 genes are linked: 3 classes of offspring, one common, one uncommon and one rare. The numbers do not add up as most common are parental types and least common are double recombinants, these would not have been included.
4
Q
Linked if…
A
recombinant frequency is less than 50%
5
Q
How do you deduce order?
A
Gene in the middle must be the one that undergoes double recombination, look at which ones have swapped over in the least and most common.
6
Q
Hints for three point testcross
A
- Look at patterns: 2 or 3?
- Determine parental and double recombinant
- Deduce gene order
- Calculate distances
