Recombination

Question 1

What is a linked gene?

Answer 1

A gene that tends to be inherited with another one

Question 1

Genes on different chromosomes

Answer 1

Assort independently

Question 2

Know how to determine if genes are assorting independently

Answer 2

Not expected (9:3:3:1)

Question 3

Know the notation for crosses with linkage

Answer 3

A B

Question 4

5. Know how to calculate recombination frequency

Answer 4

Recombinants/total offspring * 100%

Question 5

 when a crossover occurs, only the __________ are involved in the crossover

Answer 5

middle chromatids

Question 6

Differentiate between coupling (cis configuration) and repulsion (trans configuration)

Answer 6

Coupling/cis- WT alleles found on one chromosome, mutants are found on the other
Repulsion/trans- Each chromosome has one WT and one mutant allele

Question 7

Know the notation for coupling and repulsion

Answer 7

Coupling: a–b– / A+B+
Repulsion: A+b– / a–B+

Question 8

9. Understand how the configuration of alleles (whether they are cis or trans) can change the progeny phenotypic
   ratios

Answer 8

Cis (Coupling)-
Trans (Repulsion)-
??????

Question 9

10. Understand Connecting Concepts “Relating Independent Assortment, Linkage, and Crossing Over.” This is an
    excellent summary

Question 10

Be able to predict the proportions of offspring expected when the recombination frequency is given

Question 11

 crossing over occurs

Answer 11

randomly

Question 12

13. Define three-point testcross

Answer 12

 testcross involving three linked genes
 better than two-point testcrosses because only 1 cross is needed rather than multiple two-point testcrosses–
also two-point testcrosses can miss double crossovers

Question 13

Understand how to create a genetic map from a three-point testcross. Here are the steps:

Answer 13

1. Write genes in correct order
2. Locate crossovers
3. Calculate recombination frequencies
4. Construct gene map
5. Calculate coefficient of coincidence
6. Calculate interference

Question 14

Incompletely linked genes are so close together on the same chromosome that always travel together into a gamete

Answer 14

(do not
sort independently)

Question 15

 1% recombination =

Answer 15

1 map unit = 1 centi-Morgan

Question 16

 2 genes far apart are ________ crossover than 2 genes close together

Answer 16

more likely to

Question 17

 distance between genes is proportional to __________
 this allows us to create a _________ measured in ________

Answer 17

recombination frequency, genetic map, map units

Question 18

with a single crossover between 2 genes, ____ of the gametes will be ___________ gametes (and
___ will be ______________)

Answer 18

50%, recombinant, 50%, nonrecombinant

Question 19

If a crossover occurred between 2 genes every time that meiosis occurred, 50% of the
gametes will be ___________
 therefore, the _____________ is ___

Answer 19

recombinant, maximum recombination frequency, 50%