Linkage and genetic mapping Flashcards Preview

Bio 233 > Linkage and genetic mapping > Flashcards

Flashcards in Linkage and genetic mapping Deck (15)
Loading flashcards...
1
Q

Genes on the same chromosome are inherited together (syntenic)

A

Linkage

2
Q

Set of linked genes

-Genes located on chromosome 4 are in linkage group IV

A

Linkage group

3
Q

Constructed based on the rate of recombination between linked genes using test crosses
-determine the order/arrangement of genes on a chromosome

A

Linkage map (genetic map)

4
Q

Place on a homologous pair of chromosomes at which a physical exchange is occurring (site of cross over)

A

Chiasma

5
Q
  • The reciprocal exchange of chromatid segments at corresponding positions along homologous chromosomes (involves breakage and rejoining of 2 chromatids)
  • leads to genetic recombination (different combination of alleles in the progeny)
A

Crossing over

6
Q

Two extreme scenarios

A
  1. Independently assort

2. Genes are very close on the same chromosome

7
Q

Genes are on different chromosomes or far apart on same chromosome

A

Independently assort

8
Q

No recombination between genes

A

Genes very close on the same chromosome

9
Q

Distance between genes (or cM for centiMorgan)

A

Map units (mu)

10
Q

% recombination = #recombinants / Total # progeny

A

Map units calculation

11
Q

Cross a triple heterozygote with a triple homozygous recessive

A

Mapping three genes using a three-point testcross

12
Q

Occurs when two chiasmata form and there is a double exchange between two nonsister chromatids

A

Double Cross Over

13
Q

Important to Remember!

A

The expected frequency of DCO gametes is much lower than that of either SCO gamete class.
-DCO is less likely to happen than single crossover

14
Q

Important to Remember!

A
  • Progeny in the lowest abundance result from DCO

- Progeny in the highest abundance is parental

15
Q

Limits to Genetic maps

A
  • DCO do not happen as often as predicted
    • one chiasma inhibits formation of another nearby chiasma: interference
  • Sometimes DCO can restore/maintain the parental phenotype
  • Crossing over is not random; there are recombination hot and cold spots