Genetics MCM 2

Question 1

polymorphisms

Answer 1

naturally occurring variations in DNA sequences

Question 2

single nucleotide polymorphisms (SNPs)

Answer 2

variation at a single nucleotide

Question 3

linkage disequilibrium

Answer 3

non-random association of alleles at different loci

Question 4

restriction fragment length polymorphisms (RFLPs)

Answer 4

sites recognized by specific restriction endonucleases. can serve as markers to cut DNA into diff lengths
Ex: sickle-cell allele

Question 5

what are the 2 types of repeat length polymorphisms?

Answer 5

1. microsatellite repeats–2-6bp repeated more than 1000 times. exist in STRPs. used in forensics and paternity testing.
2. minisatellite repeats– up to 70bp repeated more than 1000 times. exist in VNTRs (variable number tandem repeats)

Question 6

copy number variants

Answer 6

structural variation in which large (thousands to millions) sections of the genome are repeated and the number of repeats in the genome varies between individuals in the human population.
usually immunological or nervous

Question 7

unlinked genes

Answer 7

inherited together only 50% of the time. usually either on different chromosomes or on same chromosome but far apart

Question 8

linked genes

Answer 8

show less than 50% recombination between them. gene of interest and marker are close together on same chromosome

Question 9

allele frequncies

Answer 9

proportion of chromosomes that contain a specific allele.

two chromosomal loci per individual

Question 10

hardy weinberg equilibrium

Answer 10

allele and gene frequencies should remain constant in absence of other forces.

Question 11

founder effect

Answer 11

The reduced genetic diversity that results when a population is descended from a small number of colonizing ancestors.

Question 12

natural selection

Answer 12

Increases the frequencies of alleles that promote survival or fertility

Question 13

heterozygote advantage

Answer 13

When recessive allele is hidden in a heterozygote and confers some advantage against disease (infection or environment)

Question 14

genetic drift

Answer 14

In a small population, random effects other than natural selection (increased fertility overall, survival of carriers) cause allele frequencies to change from one generation to the next

Question 15

gene flow

Answer 15

When one population is located close to another they tend to have similar gene frequencies

Question 16

consanguinity

Answer 16

Mating of related individuals

Question 17

Allele-Specific Oligonucleotide (ASO) Probes

Answer 17

• Short nucleotide sequences that bind to a common allele
• Will base pair with correct sequence
• Probe hybridization can indicate genotype
o Probe is linked to a dye so it can be detected

Question 18

trinucleotide repeat mutations

Answer 18

• Expansion of a stretch of trinucleotides
• Usually contain G and C (CGG common)
• Results in unstable DNA
• slipped mispairing causes expansion of repeats
• Impairs gene function

Question 19

anticipation

Answer 19

worsening symptoms and earlier onset of dz with each affected generation

Question 20

germline mosaicism

Answer 20

type of genetic mosaicism where more than one set of genetic information is found specifically within the gamete cells.

Question 21

inversion

Answer 21

• A rearrangement within a chromosome due to two breaks and then reincorporation
• Most common on chrom #9

Question 22

isochromosome

Answer 22

• One arm is lost and the other duplicated resulting in two small or large arms
• Leads to partial trisomy or monosomy

Question 23

robertsomian translocation

Answer 23

• Between two acrocentric chromosomes (large q arm and small mostly non-coding p arm, ie centromere is located very near the end)
• Results in one large chromosome and one extremely small which is usually lost
o These sequences are usually non-coding or highly redundant and it can support life

Question 24

uniparental disomy

Answer 24

• Both chromosomes in a homologous pair are contributed by one parent
• Can cause a problem due to imprinting or mutation