1-18 Genetic Variation Genome Mapping Flashcards Preview

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Flashcards in 1-18 Genetic Variation Genome Mapping Deck (12)
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1
Q

Segregation

A

Sexually reporducing organisms possess genes that occur in pairs and only one member of this pair is transmitted to the offspring

2
Q

Independent assortment

A

Genes at different loci are transmitted independetly

3
Q

Hardy-weinberg

A

In an ideal or model pop the relative proportions of different genotypes remain constant from one generation to another

p2 +2pq + q2 = 1 given p+q=1

4
Q

Assumptions made by Hardy-weinberg

A
  1. no new mutation
  2. no selection for or against particular gentoype
  3. no chance fluctuations due to small pop size
  4. no selection of partner on basis of genotype
  5. no migration of new genes into gene pool
5
Q

Non-random mating affect HW

A

effects HW, results in increase in freq of homozygous genotypes at teh expense of heterosygoutes compared to what would be predicted by HW

stratification: pop in which there are subgroups that are genetically seperate (eg causcasin, AA, hisp)
assortative mating: choice of mate is not randome
consanguinity: mating between people with common haplotype have higher risk of congential anomalies (eg first cousins)

6
Q

non-constant allel freq affect HW

A

genetic drift: in small pop allele freq can deviate substatiannly one generation to next

founder effect

gene flow: occurs as pop migrates and beins to mate with another pop, through time will make 2 pops more similar to one another eg PKU once only celtic and now more widespread

7
Q

founder effect

A

small pop breaks off from larger pop and allel freq in small pop may differ from parent group and a rare allele will become over represented in these descendants

8
Q

heterozygote advantage

A

increased fitness over homozygous mutition and homo normal allele

ex sickle cell disease hetero resistant to malaria

9
Q

linked loci

A

transmitted together rather than independently

depends on physical distance btw genes on chrom

10
Q

recombination frequency

genetic distance

A

the % recomb seen btw 2 loci in a large series of meioses

genetic distance: unit measure of recom, centiMorgan, 1 cM = 1% recomb

11
Q

Logarithm of the odds “LOD score”

A

log (likelihood of observing the pedigree data if the loci are linked / likelihood of observing the pedigree data if the loci are unlinked)

unliked likehood: 0.5
ratio > 1 indicates more likely than random chance
ration < 1 more likely due to chance

LOD > 3 indicates the likelihood in favor of linkage is 1000x > than the likelihood against linkage significant

12
Q

genome wide association studies GWAS

A

tests for altered freq of allele or haplotype in affected individuals compared with normal controls

does not ID the disease gene, but uses a nearby (linked) polymorphism to ID the association