Lectures 11 & 12: Gene Mapping Flashcards Preview

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Flashcards in Lectures 11 & 12: Gene Mapping Deck (45)
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1

Define a linkage map

This is a genetic map of a species or experimental population that shows the position of its known genes or genetic markers relative to each other in terms of recombination frequency (cM), rather than specific physical distance along each chromosome.

2

What is association mapping also known as?

Linkage disequilibrium mappinng

3

What is association mapping?

This is a map that required the mapping of quantitative trait loci taking advantage of historic linkage disequilibrium to link phenotypes to genotypes.

4

When does recombination occur?

Meiosis - zygotene

5

What is the main determinant of haplotype patterns?

Recombination frequency

6

T/F: Genes that are far apart on a chromosome will exhibit less crossover events thus recombination compared to those that are closer together

False

7

Which two phenotypes did Morgan use in his linkage experiments?

Red vs purple eyes and normal vs vestigial wings

8

T/F: Morgan performed a backcross experiment?

True

9

What is the formula for recombination faction?

Number of recombinant progeny/ total number of progeny

10

What are syntenic loci?

Loci that are on the same chromosome

11

1% recombination corresponds to how many cM

1 cM

12

What is the range for recombination faction?

0.0-0.5

13

What does a recombination frequency of 0.0 imply?

That the two loci are so close together that recombination does not occur between them

14

What does a recombination frequency of 0.5 imply?

That the two loci are unlinked and this is equivalent to independent assortment which occurs for alleles of loci that are on different chromosomes

15

Define Linkage phase

The arrangement of alleles on each chromosome

16

Define Haplotype

The combination of alleles on each chromosome

17

What is a genetic marker?

A DNA sequence with a known location on a chromosome; primers

18

What are RFLPs?

Restriction Fragment Length Polymorphisms

19

What are VNTRs?

Variable Number Tandem Repeats

20

What are SNPs?

Single Nucleotide Polymorphisms

21

T/F + explain: Marker loci can infer information on the causation of a genetic disease?

False; a marker locus simply designates which chromosome is being transmitted by the parent which has nothing to do with the actual causation of the disease.

22

T/F: Linked markers can be typed at any age?

True

23

Name three factors that influence crossover rates

Oogenesis, telomeric regions and recombination hot spots

24

Name a situation of an informative pedigree.

Where a homozygous dominant mates with a homozygous recessive or a heterozygous mating with a homozygous recessive

25

Give an example of a non-informative pedigree

Two heterozygotes or two homozygous recessive matings

26

Does informative/ non-informative pedigrees show they are homo/heterozygous for the disease locus?

No, there is either one or two copies of a two-allele RFLP, SNP, VNTR or microsatellite which are closely linked to the disease locus.

27

Name three characteristics that make marker loci useful.

Codominance to determine linkage phase, numerous and highly polymorphic

28

Why is polymorphic loci useful in linkage mapping?

This increases the probability that matings will be informative as it ensures that most parents will be heterozygous for the marker locus, making it easier to establish linkage phase in families.

29

How can marker loci help build a recombination map?

They help narrow down the size of the region that contains the disease causing locus.

30

What statistical measure is used to ensure that linkage was not observed by chance?

The Logarithm of the Odds score; LOD (Z)