2.0 Genetic Variation and Human Populations Flashcards Preview

MedST IB: Human Reproduction (HR) > 2.0 Genetic Variation and Human Populations > Flashcards

Flashcards in 2.0 Genetic Variation and Human Populations Deck (21)
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1

How many nucleotides in the human genome?

3 billion

2

how many genes in the human genome?

20,000 (2% of genome)

3

What percentage of genetic content do humans share?

95%

4

What are the different classifications of variation in human genomes?

1) Single nucleotide polymorphisms (SNPs)
2) Insertion/deletions (indels)
3) Larger scale structural variation

5

Define alleles:

Different versions of a genetic locus

(most variant alleles are unique to that individual)

Pairs of alleles = genotype

6

What processes affect genomic evolution?

1) Genetic drift
2) Natural selection
3) Germline mutations
4) Demography

7

Define genetic drift:

Random change in allele frequency from one generation to the next

8

"What is ""fixation"" and ""loss"" with regards to reduction of genetic diversity?"

Fixation = 100% allele frequency
Loss = 0% allele frequency

9

Is genetic drift more common in smaller or larger populations:

Smaller populations

10

Define founder effect:

Founder effects
- Loss of genetic diversity when new population is set up by small number of individuals

11

Define Genetic bottleneck

Genetic bottleneck
- Sharp reduction in population size due to environmental/human events

12

What genetic diseases are associated with:
1) Amis/Hutterite/Mennonite communities
2) Ashkenazi Jews
3) Finnish people

1) Amish/Hutterite/Mennonite communities
- Microcephaly
- Other genetic diseases
2) Ashkenazi Jews
- Tay-Sachs
3) Finnish people
36 monogenic diseases are higher in Finnish populations

13

Define selective sweep:

Sign of positive selection
It is the reduction/elimination in variation due to strong +ve selection
Result = extended region of genetic homogenisity

14

What gene is involved with the selective sweep for lighter skin in Europeans?

SLC24A5

15

What caused lactase persistence in Europeans?

A single mutation

16

How many new mutations are there in each individual?

~60

17

What is the relationship between paternal age and de novo mutations?

Increase paternal age -> Increase de novo mutations

18

Give examples of mandelian/simple diseases:

1) Cystic fibrosis
2) Down's syndrome
3) Sickle-cell disease
4) Charcot-Marie-Tooth disease

19

Given examples of diseases that are influenced by both environment and genetics:

1) Alzheimers
2) CVS disease
3) Type II DM
4) Parkinson's disease

20

What is a GWAS?

Genome-wide association study
Examination of many common genetic variants in different individuals to see if any variant is associated with a trait. GWASs typically focus on associations between single-nucleotide polymorphisms (SNPs) and traits like major diseases

21

What is linkage disequilibrium?

Non-random association of alleles at different loci i.e. the presence of statistical associations between alleles at different loci that are different from what would be expected if alleles were independently, randomly sampled based on their individual allele frequencies