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Flashcards in More genetics Deck (76)
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1

What is codominance?

Both alleles contribute to the phenotype

2

What is variable expressivity?

Phenotype varies among individuals with the same genotype

3

What is incomplete penetrance?

Not all individuals with a mutant genotype show the sme phenotype

4

What is pleiotropy?

One gene contributing to multiple phenotypic effects

5

Musty body odor = ?

PKU

6

What is the loss of heterozygosity?

Two hit phenomenon

7

What is a dominant negative mutation?

A heterozygote produces a nonfunctional altered protein that also prevents the normal gene product functioning

8

What is linkage disequilibrium?

Tendency for certain alleles at 2 linked loci to occur together more often that expected by chance

9

What is locus heterogeneity?

Mutations in the same locus produce a similar phenotype

10

What is allelic heterogeneity?

Different mutations in the same locus produce the same phenotype

11

What is heteroplasmy?

Presence of both normal and mutated mtDNA, resulting in variable expression in mitochondrial inherited disease

12

What is uniparental disomy?

here an offspring receives 2 copies of a chromosome from 1 parent, and no copies from the other.

13

What does heterodisomy (a uniparental disomy) result from?

Meiosis I error

14

What does isodisomy (a uniparental disomy) result from?

Meiosis II error

15

What is the Hardy-Weinberg equation?

= {p^2 + 2pq + q^2 : p and q are the frequencies of separate alleles}

16

What are the four assumptions made in the Hardy-Weinberg equation?

1. No mutation
2. Natural selection is NOT occurring
3. Random mating
4. No net migration

17

What is imprinting?

Methylation of a certain set of genes, causing silencing

18

What is the cause of Prader-willi syndrome?

Paternal gene deleted on 15q

19

What is the cause of Angelman syndrome?

Maternal gene deleted on 15q

20

What are the symptoms of Prader-Willi syndrome?

Food seeking, MR, obesity

21

What are the symptoms of Angelman syndrome?

MR, Happy puppet

22

What is the inheritance pattern of hypophosphatemic rickets (vitamin D deficient rickets)?

X linked dominant

23

What is the inheritance pattern of MEELAS and MRRF?

Mitochondrial

24

What is the genetic defect in autosomal dominant polycystic kidney disease? (which two proteins on which two chromosomes)

Mutation in PKD1 on chromosome 16 and PKD2 on 4

25

What is the genetic cause of familial adenomatous polyposis (HNPCC)? Which chromosome is this on?

Mutation of APC gene on chromosome 5

26

What is the genetic defect in familial hypercholesterolemia?

Defective LDL receptor

27

What is hereditary hemorrhagic telangiectasia?

Inherited disorder of blood vessels

28

What is hereditary spherocytosis?

Spheroid erythrocytes due to spectrin or ankyrin defect

29

What is the genetic bases of huntington's disease?

CAG repeats on chromosome 4

30

What are the two neurotransmitters in the brain that are decreased in Huntington's? What two areas of the brain are most affected?

GABA and ACh

Caudate nucleus and putamen