Genetic Variation

Question 1

Name the four conditions associated with the Hardy-Weinberg equilibrium

Answer 1

1. Large population
2. Random mating (no stratification aka a subpopulation, no assortive mating, and no consanguinity)
3. No mutation
4. No selection (all genotypes are equally capable of mating and producing offspring)

Question 2

Gene flow

Answer 2

slow movement of genes between populations, causes variation in allele frequencies (HW exception)

Question 3

Genetic drift

Answer 3

Involves chance changes with the environment favoring a genetically defined subpopulation (odds of mating among carriers increases)

Question 4

Founder effect

Answer 4

When a small population with a different allele frequency breaks away from the general population and there is a population expansion in the new location

Question 5

Balanced polymorphism

Answer 5

a polymorphism (so variation in alleles) that is regulated by forces that remove affected (mutated) alleles from populations by utilizing heterozygous advantage: more viable phenotype than a homozygote (sickle cell & malaria ex)

Question 6

Hardy-Weinberg Principle

Answer 6

frequencies of genotypes AA, Aa, and aa (p+q)^2= p^2 +2pq+ q^2

where p+q=1

Question 7

Haplotype

Answer 7

a sequence of genes mapping in very close proximity to one another that are generally inherited together (linked loci) i.e. HLA A, B, C

Question 8

Disregarding crossing over, siblings have a _____% chance of sharing both alleles of the MHC haplotype. What is the consequence of this?

Answer 8

25%, siblings are better matching donors than parents (who only share a single allele)

Question 9

Linkage disequilibrium

Answer 9

Combos of alleles are acquired in coupling more frequently than by chance alone as defined by individual allele frequencies within the total population–> limited # of haplotypes in an ethnic group.

Question 10

What will you see linked to HLA associated diseases?

Answer 10

autoimmunity or anti-infectious nature (ankylosing spondylitis)

Question 11

List the blood types, their mode of inheritance, which antigen is present, and which Abs will be present in the blood

Answer 11

O–> recessive–> no ag–>anti-A and anti-B
A–>dominant–>N-acetylgalactosamine–> anti B
B–>dominant–> galactose–> anti A
AB–>codominance–> both NAG and G–> no abs

Question 12

Explain the DNA fingerprinting process

Answer 12

Minisatellite repeats (VNTRs) are cut with a restriction enzyme, then gelelectrophoresis, and a probe (Southern blotting). Several VNRTs are compared simultaneously

Question 13

STRPs (short tandem repeat sequences) are more ____ and more _______ than VNTR minisatellites, so they are used for ______ and ________. You can detect them via _____ with flanking primers and ___________.

Answer 13

frequent, polymorphic, gene mapping, forensics, PCR, gel electrophoresis

Question 14

What are SNPs and what can they indicate?

Answer 14

Single nucleotide polymorphisms that confer subtle alterations in disease susceptibility.

Question 15

Define a polymorphism

Answer 15

variant sequences of a gene occurring at an allele frequency >1% (not necessarily deleterious)

Question 16

What 5 parameters determine germline mutation risk?

Answer 16

1. Gene size
2. Mutation phenotype (visibility)
3. Parental age
4. Parental Gender
5. CG sequences

Question 17

Maternal gametes spend most of their time in _________ and as a mother ages, the risk for ____________ increases, causing large deletions from ________ __________ and _______ _______ exchanges during meiosis. Therefore we see inheritance of _______ from mom.

Answer 17

Meiosis I, nondisjunction, unequal crossover, sister chromatid, indels

Question 18

Paternal gametes undergo ______ as they sit, which increases the risk for replication errors with age, and therefore increase the possibility of _____ ________. We see inheritance of ______ __________ from dad.

Answer 18

mitosis, nucleotide (bp) mutations, point mutations

Question 19

What is the most common mutation type that causes disease?

Answer 19

Missense

Question 20

What are the three mutation types (think macroscopic) ?

Answer 20

Genome (via chromosome missaggragation), chromosome (via chromosomal arrangement), gene (via base pair mutation)