8.23.16 Lecture Flashcards Preview

MCBG > 8.23.16 Lecture > Flashcards

Flashcards in 8.23.16 Lecture Deck (37)
Loading flashcards...
1

Genetic variation defines ___ (phenotypic variation) and ethnic differences, provides us with markers of ___, and defines susceptibility to disease.

Inter-individual differences; disease

2

What is the general format of mutation notation?

Type of sequence, nucleotide number, nucleotide, > replacement nucleotide

3

What are the abbreviations for the 5 types of sequence?

g: genomic
c: cDNA
m: mitochondrial
r: RNA
p: protein

4

The nucleotide is capitalized for which type of sequence? Lowercase for which type of sequence?

Genomic; RNA

5

In introns, a mutation is noted as ___#, where the donor splice site G is assigned position ___.

IVS (Intervening Sequence); +1

6

How are deletions and insertions notated?

By start and stop nucleotide # separated by _ then del or ins followed by affected nucleotides

7

How are translated mutant sequences notated?

Original aa in 3 letter code, position in protein, replacement aa or X for stop codon

8

What are polymorphisms?

Variant sequences (not necessarily deleterious) occurring at an allele frequency >1%

9

What are the 5 types of typical polymorphisms?

1. Single nucleotide polymorphisms (SNP; 2 alleles)
2. Simple insertions or deletions (indols; 2 alleles)
3. Short tandem repeat sequences (STRP; 5+ alleles)
4. Variable number tandem repeat sequences (VNTR; 5+ alleles)
5. Copy number polymorphisms (CNP; 2 alleles)

10

What are three examples of polymorphisms?

ABO, Rh, and MHC

11

How are ABO blood groups defined?

By glycosyltransferase that adds either N-acetylgalactosamine residues (A) or D-galactose residues (B) or no sugars (O) to the H-antigen on RBC.

12

What are the phenotypes, attached sugars, inheritances modes, and antibodies in serum for the 4 blood groups?

O - no sugar - recessive inheritance - anti-A, anti-B
A - N-acetylgalactosamine - dominant inheritance, anti-B
B - galactose - dominant inheritance, anti-A
AB - both types of sugar - co-dominant inheritance - neither

13

What is the universal blood donor?

O

14

What is the universal blood recipient?

AB

15

The Rhesus factor, expressed on RBC, is encoded on chromosome ___. Mutations are inherited ___.

1; autosomal recessive

16

What are the two Rhesus phenotypes, the corresponding presence of Rh-D polypeptide on RBC surface, mode of inheritance, and antibodies Rh-D in serum?

Rh negative - Rh-D polypeptide absent - recessive inheritance - antibodies to Rh-D present

Rh positive - Rh-D polypeptide present - dominant inheritance - antibodies to Rh-D absent

17

What are MHC class I and class II and what do they do?

Major histocompatibility complexes; define expression of human lymphocyte antigen (HLA) needed to present antigen to specific T-cells.

18

MHC complexes are encoded on which chromosome?

6p

19

Matching ___ is pivotal for transplants.

HLA

20

The MHC cluster is inherited as a haplotype - what does this mean?

These genes are mapped in close proximity to another another and are thus inherited together; very dense part of the genome, highly polymorphic, many alleles

21

Disregarding crossing over, siblings have a ___ chance of sharing both alleles of the MHC haplotype.

25%

22

Knowing ___ and ___ frequencies in a population allows us to calculate risk.

Genotype; allele

23

What does the Hardy-Weinberg equilibrium do?

Describe the relationship between allelic frequencies and genotype frequencies in a stable population

24

What is the Hardy-Weinberg equilibrium equation?

(p+q)^2 = p^2 + 2pq + q^2; p and q must remain constant, p + q = 1

25

What is the Hardy-Weinberg equilibrium equation for 3 possible alleles?

(p+q+r)^2

26

Disease frequency = ?

q^2

27

How does the Hardy-Weinberg equilibrium change for sex-linked diseases?

Genotype frequency = allele frequency in males

28

What are the 4 conditions necessary for Hardy-Weinberg Equilibrium?

1. Large population (not influenced by chance fluctuations)
2. Random mating (no preference based on phenotype similarities)
3. No mutation (no conversion of P allele to Q allele)
4. No selection (all genotypes are equally capable of mating/producing offspring)

29

Generally, random mating means what 3 things?

1. No stratification (subpopulation exists that remains genetically separate)
2. No assortative mating (choice of mate determined by common trait)
3. No consanguinity

30

What are the three major exceptions to Hardy-Weinberg equilibrium?

1. Gene flow: slow movement of genes between populations
2. Genetic drift: chance changes with the environment favoring a genetically defined subpopulation
3. Founder effect: small population with different allele frequency breaks away from general popualtion