Exam 1- lectures 1 & 2 Flashcards Preview

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Flashcards in Exam 1- lectures 1 & 2 Deck (49):
1

How much of the genome codes for proteins?

2%

2

how much of the genome is "junk DNA"?

50%

3

how much "difference" do we see in people?

0.1%

4

locus

the position of an allele on a chromosome

5

allele

a variant of a gene

6

central dogma

DNA->mRNA->protein

7

what DNA is inherited?

DNA in gametes

8

4 types of SNP mutations

silent, conservative missense, non-conservative missense, nonsense

9

conservative missense mutation

amino acids are similar and the protein function is similar

10

silent mutation

leads to the same amino acid

11

non-conservative mutation

amino acids are different, so chaped & function of protein will change

12

nonsense mutation

codes for a stop codon

13

most clinically impactful mutations

nonsense & non-conservative

14

incomplete dominance

both traits are expressed; blended-> pink

15

co-dominance

not blended; both expressed equally-> red & white spots

16

mendelial genetics

monogenic

17

quantitative traits

(expressivity) traits that vary in the extent to which they are expressed in each individual (i.e. height & weight)

18

incomplete penetrance

not every individual who has the genotype expresses the phenotype; other genes may affect the phenotype

19

multifactoral traits

both environment and genetic components (hemochromatosis)

20

genetic switching

fly eyes
after the genes have already been made, change due to environmental factor & new gene will be passed on to offspring

21

how many deleterious genes does each person carry?

estimated 5-8

22

pleiotropism

a mutation in a single gene can lead to many effects

23

genetic heterogeneity

mutations at several genetic loci may produce the same trait

24

huntington's diease

autosomal dominant
triplet repeat on chromosome 4
dysfunctional protein builds up -> toxic GABA neurons
hyperkinesis, parkisonian rigidity, bradykinesia, death w/in 15 years

25

familial hypercholesterolemia

autosomal dominant
defective LDL receptor-> inability to bind LDL & transport
atheroscleosis, MI by 20 yo

26

autosomal dominant diseases

huntington's disease
familial hypercholesterolemia

27

autosomeal recessive dieases

PKU,
cystic fibrosis
sickle cell anemia

28

phenylketonuria (PKU)

defective phenylalanine hydrocylase
phenylalanine is not catabolized-> build up in CNS-> severe mental retardation

29

cystic fibrosis

defective Cl ion channel-> thickened mucus secretions
resp. infections, pancreatic dysfunction, impaired male fertility

30

sickle cell anemia

defective HbS
sickling of RBCs-> blockage of blood vessels-> tissue hypoxia

31

x-linked recessive diseases affect who most?

males bc X is inherited from mother

32

x-linked recessive dseases

hemophilia A & B
GPPD deficiency
diabetes insipidus

33

hemophilia A & B

defect in clotting factors 8 & 9
-> prolonged bleeding due to inability to form a fibrin clot

34

G6PD deficiency

usually asymptomatic until triggered (drugs, infection, fava beans)-> RBC unable to repaid

35

diabetes insipidus

mutation in AVPR2 gene-> defective vasopressin receptor

36

what is the most common enzyme deficiency in humans?

G6PD

37

polygenic traits

height, intelligence, BP, skin color, metabolic parameters

38

polygenic continuous diseases

HTN, DM

39

polygenic congenital malformations

cleft lip & palate, pyloric stenosis, anencephaly, congenital heart disease

40

polygenic discontinuous diseases

manic-depressive psychosis, rheumatoid arthritis

41

diseases due to non-disjunction

down's syndrome (trisomy 21)
turner's syndrome (X0)
klinefeiter's syndrome (XXY)

42

positive selection examples

alcohol tolerance
lactose tolerance
sickle cell anemia- heterozygous protects against malaria
CF- protects against thyoid
tay sachs- protects against TB
type AB blood- resistant to cholera

43

gene-environment interaction examples

multiple sclerosis, asthma, factor V leiden & OCPs

44

multiple sclerosis

higher incidence far from equator (US, Canada, N. Europe)

45

increased risk of venous thrombosis in oral contraceptive users who are carriers of what mutation?

factor V leiden mutation

46

what is the most common cardiovascular event in young women?

venous thrombosis

47

factor V Leiden mutation

ARG replaced by GLN at 506
R506 is the cleavage site for aPC
R506Q is not cleaved, there fore factor V is not inactivated
overproduction of thrombin & fibrin-> excessive clotting

48

ACMG recommendations when to do genetic testing for Factor V Leiden mutation & OC use

-<50, MI and smoker

49

routine genetic screening

trisomy 21, trisomy 12, sick cell, GALT, CF, G6PD, PKU, Beta-thelassemia, etc