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Cellular Genetics and the Cell Cycle > Introduction to Genetic Variation > Flashcards

Introduction to Genetic Variation Flashcards

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1
Q

Definition of DNA polymorphism

A

Differences in base sequences between humans by 0.1%

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2
Q

Definition of biallelic

A

Have 2 alleles, 2 copies

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3
Q

Definition of haplotypes

A

Series of SNP alleles along a single chromosome

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4
Q

Definition of genotypes

A

2 alleles, present at a SNP in an individual

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5
Q

Definition of alleles

A

Single copy, allele A, G, C, T

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6
Q

Definition of linkage disequilibrium

A

Non random association of alleles at 2 or more loci in a general population. Haplotypes do not occur at the expected frequencies

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7
Q

Definition of SNP

A

Single nucleotide polymorphism, single base substitutions that occur throughout genome

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8
Q

Definition of tandem repeat polymorphisms

A

Repetitive sequences of DNA, individuals carry different non of repeats

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9
Q

Definition of structural variation

A

Segment of DNA that can be absent in same chromosomes or present in multiple tandem copies

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10
Q

Definition of Hardy Weinburg equilibrium

A

Explains stability of allele and genotype frequencies within a population

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11
Q

Definition of genetic drift

A

Random changes in genetic variants

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12
Q

Definition of selection

A

A change that favors 1 allele in a population due to higher fitness of some genotypes

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13
Q

Definition of fitness

A

Measures the ability of genotypes to reproduce

Measured on a scale between 0-1

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14
Q

Definition of heritability

A

Proportion of phenotypic variation due to genetic differences among individuals

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15
Q

What are DNA polymorphisms considered

A

Neutral variations in DNA sequence

Common in general population (freq>1%)

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16
Q

Contrast DNA polymorphisms with mutations that cause Mendelian diseases

A

Dominantly inherited variants v rare

Recessive mutations more common

17
Q

Forms of genetic variation

A

Single nucleotide polymorphisms (SNP)
Tandem repeat polymorphisms
Structural variation

18
Q

What is a SNP

A

Single base substitutions occur throughout genome, most common
Can occur in exons without detrimental effects
Roughly 10mn in 1 genome
Some associated with phenotypic differences
Generally are biallelic

19
Q

The relationship between 2 closely located SNPs

A

SNPs in same genetic region may be correlated
In linkage disequilibrium
Knowing the allele at SNP1 gives information on allele at SNP2

20
Q

What is a tandem repeat polymorphism

A

Non coding DNA mainly consists of repetitive sequences
Individuals carry different non of repeats
No of base pairs in a repeat can be from 2 and more base pairs
Microsatellite markers
Used in forensic investigations

21
Q

What is structural variation

A

Segment of DNA that can be absent in some chromosomes or present in multiple tandem copies
Known as copy no variant (CNV)/polymorphism (CNP)
Segments contain 100s of genes, have impact on health, increase risk of disease

22
Q

Assumptions in Hardy Weinburg equilibriums

A 
Large populations
No migration
No new mutations
No selection
Random mating
23
Q

What is the Hardy Weinburg equilbrium

A

Frequency of alleles and genotypes will remain stable across generations

24
Q

Hardy Weinburg equations

A

p+q=1 allele frequency

p^2 + 2pq + q^2=1 genotypes frequency

25
Q

How does allele frequency change

A

All genetic variants change in frequency over long time due to genetic drift

26
Q

What is selection

A

Acts on top of random drift, normally leads to much faster changes in allele frequencies over time
Leads to increase in frequencies of 1 allele in population due to increased fitness of some genotypes

27
Q

What is fitness

A

Measures the ability of genotypes to reproduce

0 (no reproduction)- 1 full reproductive ability

28
Q

How does migration affect diversity of genetic variants

A

Different allele frequencies between ethnic groups

29
Q

New mutations and their biological effects

A

Some incompatible w life
Some lost/not transmitted to next generation
Others may remain in gene pool
Some increases disease risk/affect trait

30
Q

What is quantitative genetics

A

Most traits have normal distribution
Quantitative characters normally determined by genes and environment
Quantitative genes have additive, equal and small effects on phenotype (polygenic)

31
Q

What is heritability

A

Proportion of phenotypic variation due to genetic differences among individuals
Can be estimated from difference in monozygotic and dizygotic twins
Estimates for continuous traits and disorders

32
Q

Multifactorial model for disease

A

Genes + environment => disease

Underlies heart disease, schizophrenia, asthma, MS

Cellular Genetics and the Cell Cycle (8 decks)

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