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Flashcards in Medical genetics final Deck (72):
1

what causes fragile X?

portion of X chromoosome dangels by a thread. unstable CGG repetition at Xq27

2

MC widespread single gene cause of autism?

fragile X

3

MC form of mental retardation?

fragile X (1/1000 males)

4

what changes pre to full retardation in fragile X syndrome?

FEMALE meisis

5

alien 3 syndrome, cause and genotype?

XYY, anaphase II of meisois II error in chromosome separation, 1/1000 males

6

XXY phenotype?

taller than average males, not excessively violent

7

how do humans have most phenotypic variation with least genotypic variation among mammals?

epigenetics, epigenome and regulation

8

klinefelters genotype?

47, XXY

9

klinefelters phenotype?

mostly male phenotype; with androgenous characteristics:
hypogonadism, low T, weaker muscles and reduced strength, taller, less muscle and fail and body hair, broad hips, weaker bones, low energy.

10

3 control points of chromatin stage regulation?

histone methylation, histone acetylation, other modification?

11

what are target sites for histone methylation and what do they do?

cystidine residues dinucleotide (CpG), which down regulate transcritption

12

what occurs with histone acetylation?

DNA does not get condensed. active transcription is increased

13

what else modifies histones?

phosphate

14

chromatin vs nucleosome vs hsitone?

histone are the protein that organizes DNA for expression. chromatin is the form of the whole thin. nuccleosomes are the spool around which dna winds

15

introns vs extrons

non-coding, affect mRNA regulation vs coding areas of DNA which can be turned into proteins

16

can extrons be shuffled?

yes

17

CGCG sequence do what?

target sequence for enzyme to cleave DNA

18

3 sources of regulating transcription?

promoters (CCATT or TATA boxes) - immediately before the gene
exon shuffling
enhancers (transcription factors that bind enhancer regions) before the promoter region

19

what do RNA need to get in and out of nucleus?

most RNA for protein synthesis can only function outside nucleaus

20

why problem for RNA to get in and out of nucleus?

RNA is a large molecule and needs active transport

21

how RNA nuclear transport regulated? 2 sources of regulation

karyopherins are either importins or exportins and attach to RNA to move them trough nuclear pore complexes. Ran proteins GTPase proteins regulate the whole thing.

22

what are proto-oncogenes?

they are involved in nuclear transcription. code for proteins that regulate cell growth and differentiation. they have potential to become oncogenes

23

what level of tumor suppressor and oncogenes for cancer to develop?

TSG - two hit
oncogene - 1 ht

24

what three parts of cell cycle do onccogenes affect?

receptor synthesis
nuclear transcription
messenger systems

25

TSG and oncogene mutate. do they produce more or less protein?

oncogenes - more
tumor suppressor genes - less

26

regulate translation (4)

5' cap, 3' tail, removal of introns, splicing of exons, poly A binding proteins.

27

what do PABP do?

bring 5' and 3' together to enhance translation

28

what does 5' cap on mRNA do

regulates nuclear export, prevents degradation, promotes translation, prmotes intron excision

29

what does 3' tail do

proteins mRNA from destruction, promotes export, and translation

30

where are location of modications marked in epigenmic maps?

above BP sequences. altering, activating, repressing, winding/unwinding and
opening/closing sequences

31

how does proximity affect gene linkage?

during meisis recomination of genetic info occurs. the closer the gene are the less likely the are to experience crossover and may be linked

32

how to assess distance between loci on chromosomes

recomindaiton frequency. further apart more recombination

33

4 types of DNA polymorophisms?

restricted fragment length polymorophism (RFLP), variable number of tandem repeats (VNTR), short tandem repeat polymorphisms (STRP), single nucleoptide polymorphism (SNP)

34

RFLP produce

DNA of different lengths

35

which polymorphisms used in paternity testing and forensic analysis?

Variable number of tandem repeats and short tandem repeat.

36

difference between VNTR and STRP?

both repeating satellite area. STRP 2-6 bases long. VNTR areas flanked on both sides by a restriction site 20-70 bases long

37

which polymorphism is used in gene mapping?

STRP. they are throughout the chromosome and make variation for alleles.

38

what is amnioentesis?

a test for prenatal genetic testing. small sample of amniotic fluid is collected

39

what is fetal risk of amniocentesis?

.5%

40

what are 3 complicatoins of amniocentesis?

infection, bleeding, damage to amniotics sack

41

when is amniocentesis performed?

16 weeks gestation

42

BRCA 1 expressed where?

mammillary cells

43

bRCA1 genetic location?

chromosome 17, region 2, band 1

44

BRCA 1 produces what compared to BRCA 2?

breast cancer type 1 protein which sould repair doubel stranded breaks in DNA, BRCA repairs single stranded DNA breaks

45

what gene does BRCA1 interact with?

RAD51 for aids in strang break repair

46

limitations of gene therapy 4?

1) short lived - cells rapidly divide, difficult to reach all cells
2) immune response
3) viral vectors - difficult to control
4) multigene disorders - more common and difficult to target all the areas

47

RNAi what does it do and target?

interference RNA inhibits gene expression or translation by neutralizing targeted mRNA

48

who does post transcriptional gene silencing? and who does it defend against?

RNAi. defends against paraistic and viral sequences

49

RNAi inherented?

yes

50

scientific application of RNAi

silences genes for knowdown studies to understand what each gene does

51

CA 19-9 cancer?

pancreatic

52

CA 125 cancer?

ovarian

53

AFP cancer marker?

liver

54

beta HcG cancer marker?

testicular

55

BRCA increased risk for 8 cancers?

melanoma, pancreatic, gall bladder, bile duct, stomach, laryngeal, leukemia, and lymphoma?

56

BRCA 1 increase fro which 3 cancers?

ovarian, fallopian tube, prostate

57

gene control can be regulated at what 5 stages?

chromatin stage
transcriptional
translational
post translation control in cytoplasm
post translational modicfication

58

popultion genetics?

study of allele frequency change = evolution; distribution under influence of evolutional proceses

59

4 ievolutional proceses influence population genetics?

natural slection, genetic drift, mutation, gene flow

60

how does genetic drift influence allele freq?

random change

61

how does gene flow influence allele freq?

exchange of genes btw population that live near each other

62

gene mutation are they harmful?

yes 70% harmful

63

how does natural selction influence allele?

promotes those that increase survival

64

what is founder effect?

when population begins with only a few individuals. less geentic variability

65

what is hardy weinberg?

mendelian genetic stability in absence of evolutionary processes. without the process we can anaylyze how much those processes are working

66

what is only monsomy consistent with life?

turner

67

what is karyotype of turner?

45 X 50%, 46 XX, or 47 XXX

68

what is phenotype of turner syndrome?

short stature, ovarian dysgenesis,

69

how like to get breast cancer BRCA stats lifetime?

60% to 80% risk BRCA 1
40-70% BRCA 2

70

what may be responsible for fanconi anemia?

BRCA 2, with AML, and bonemarow failure by 40, endocrine problems, as well as congenital defects

71

how like to get ovarian BRCA stats lifetime?

20-40%

72

males with BRCA 2 what is CaP and BCA?

CaP by 65 15%
BCA by 70 6.8%