Genetic Variation Flashcards

1
Q

Mutation

A

Changes in DNA sequence, basis of all variation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Types of single-gene mutations

A

Base-pair substitution, insertions and deletions, duplications, control and structural types, unusual types

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Silent mutation

A

Change in one base pair, third position, no change in the amino acid, can be detected in DNA or RNA but not in protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Missense mutation

A

Change in one base pair, changes codon from one amino acid to another

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Nonsense mutation

A

Change in one base pair, becomes stop codon, truncates protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Insertion and deletion

A

Bases added to or removed from a sequence, large ones can disrupt more than one gene, small ones can change sequence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Frameshift mutation

A

Special insertion/deletion, number is not a multiple of 3, changes the “reading frame”, completely different amino acid sequence, premature truncation likely

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Mutations in non-coding DNA

A

Mutations can occur in any DNA sequence, may affect mRNA expression instead of protein sequence- promotors, enhancers, silencers, may affect mRNA processing and protein sequence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Duplications

A

Large regions, whole genes are duplicated, sometimes gene function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Transposons

A

Mobile genetic elements, can insert in or near gene and alter expression

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Expanded repeats

A

Trinucleotides, run of one amino acid, number increases, too many disrupt function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Effects of mutation

A

Loss of function mutations- protein has no activity

Gain of function mutations- protein has new or greater activity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Hemoglobin mutations

A

Structural- change protein (sickle cell anemia- glutamate 6 to valine)
Control of expression- thalassemias, hereditary persistence of fetal hemoglobin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Thalassemias

A

Defect in production of alpha- or beta-globin, tetramers form due to excess of other subunit, damage to RBCs by precipitation, shorten lifespan of RBCs, cause anemia, splenomegaly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Molecular causes of mutation

A

Ionizing radiation, nonionizing radiation, chemicals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Ionizing radiation

A

Creates reactive radicals, react with bases, cause double-stranded breaks

17
Q

Nonionizing radiation

A

Shift electrons, cause reactions (pyrimidine dimers from UV)

18
Q

Chemicals

A

Base analogs insert, react, change, deamination reactions convert C to U

19
Q

Rate of mutation

A

Influenced by size of the gene, age at reproduction, “hot spots”

20
Q

DNA repair

A

Major role is to prevent mutation, some repairs require determining which base is changed, some mutations affect more than one base

21
Q

Xeroderma pigmentosum

A

Defect in nucleotide excision repair, cannot repair pyrimidine dimers, UV causes mutations in skin cells, several related disorders of DNA repair

22
Q

Blood groups

A

Natural variation, ABO system, A and B are antigens, O lacks antigens, co-dominant, antibodies are present to antigen not present in the cell, Rh + or -

23
Q

Hardy-Weinberg rule

A

Randomly mating population, large numbers, can estimate frequency of gene variants

24
Q

Gene frequency in population

A

Important to know risk of two carriers reproducing, high gene frequency in a population increases the chance of carriers reproducing, increases frequency of homozygotes for that gene

25
Hardy-Weinberg equation
p^2 + 2pq + q^2 = 1 p = frequency of normal q = frequency of mutation q^2 = frequency of affected
26
Natural selection
Survival and reproductive advantage, higher chance of reproduction causes higher instance of gene in population
27
Genetic drift
Isolated population will change with time, due to different pressures and random events
28
Gene flow
Intermixing of populations, from small numbers or large migrations
29
Founder effect
Small numbers, large effects, very few founders, may mean gene frequencies do not reflect larger population
30
Malaria and sickle cell
Example of selective advantage, people with sickle cell are more resistant to malaria, heterozygotes not as sffected, survive longer, reproduce more, increase gene frequency