Genomic markers Flashcards

1
Q

What are genomic markers used for?

A

To carry out genetic analysis to identify a specific locus on the DNA

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2
Q

Which genetic markers are more used?

A

DNA polymorphisms

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3
Q

Minisatellites

A

Region of the DNA that is repeated: forensic genetics

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4
Q

Microsatellites

A

More frequent than minisatellites: shorter length than minisatellites

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5
Q

Advantages of using microsatellites

A
  • Easy to detect via PCR
  • present in high numbers in the genome
  • co-dominant in nature
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6
Q

Disadvantages of using microsatellite

A
  • initial identification
  • DNA sequence information necessary
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7
Q

Which projects were involved with SNPs?

A

International HapMap Project
1000 genomes

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8
Q

What does recombination mapping do?

A

Allows us to estimate the genetic distance between loci

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9
Q

Independent assortment regarding loci

A

Loci which are on separate chromosomes or on the same chromosome but are so far apart that they segregate independently

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10
Q

What happens when 2 loci are very close to each other?

A

They co-segregate: never separated by recombination

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11
Q

How do we establish the relationship between the loci?

A

In terms of the genetic relationship and distance as a function of the genetic relationship

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12
Q

If 4 types of gametes are observed what is the case?

A

Independent segregation: NOT LINKED

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13
Q

If we observe 2 parental combinations and 2 recombinant what is the case, between 0% and 50%?

A

The 2 loci are not independently segregating but are not fully co-segregating

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14
Q

When does crossing over take place?

A

At the 4-chromatid stage of propahse I meiosis

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15
Q

What happens if you have double crossing over?

A

Creates parental combinations of these 2 alleles

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16
Q

How do we measure the distance between 2 loci?

A

In terms of recombination frequency
1% recombination is 1cM

17
Q

What is the maximum number of recombination that we can measure in a genetic analysis?

A

50%

18
Q

How do we calculate recombination frequency?

A

Recombinants/ number of gametes

19
Q

How many meioses are needed to be statistically significant?

A

10

20
Q

Linkage analysis

A

Analysis in which we establish if there is linkage hence genetic association between the 2 loci

21
Q

What does it mean if the % recombination is lower than 50%?

A

The genes must be on the same chromosome

22
Q

What is the cis arrangement?

A

wt alleles on one homologous chromosome and both mutants on the other

23
Q

What is the trans arrangement?

A

Arrangement has one mutant and wt on each homolog

24
Q

What does a crossover in the cis arrangement result? and in the trans arrangement?

A

cis arrangement–> trans arrangement
trans arrangement–> cis arrangement

25
Q

How is a genetic map established?

A

From estimating the crossover rate in a particular segment of the chromosome

26
Q

What does crossover do?

A

reduce formation of other chiasmata nearby

27
Q

What does crossover produce?

A

Interference

28
Q

What is interference?

A

Total interference with no other crossovers in the region

29
Q

Coefficient of coincidence

A

double crossing over observed/ double crossing over expected

30
Q

Interference equation

A

1- coefficient of coincidence

31
Q

Mapping functions

A

Mathematical formulas used to define the relationship between map distance and recombination frequency

32
Q

Haldane’s mapping function

A

p= 1/2 (1-e^-2d)

33
Q

For which window is the estimator distance between 2 genes precise

A

7cM

34
Q

Which quantity is additive and which is not?

A

Map distance is additive; frequency of recombination is not

35
Q

Which factors influence genetic distance?

A
  1. Gender: more recombination in females than in females
  2. Chromosome structure: where the centromere is located, recombination is the lowest