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Flashcards in Genetics Deck (57):
1

what is a polymorphism

a mutation that does not cause disease

2

what is a balanced chromosome rearrangement

all chromosomal material present but have moved around/rearranged

3

what is an unbalanced chromosome rearrangement

extra or missing chromosomal material (usually 1 or 3 copies of some genome)

4

what is the name given when there is a whole extra or missing chromosome

aneuploidy

5

what is translocation

rearrangement of chromosomes

6

what is trisomy 21

Down syndrome - 47 XY

7

where is the defect in Down syndrome

Defect in gene 21

8

what is robert translocation

two acrocentric chromosomes stuck end to end

9

what is trisomy 18

Edward syndrome - 47 XY

10

what is the defect in Edward syndrome

additional copy of chromosome 18 in some or all cells of the body

11

what is Turner Syndrome

X chromosome aneuploidy
only affects females

12

what is triple X

extra X chromosome in every cell
47 XXX

13

what is Klinefelter syndrome

Only affects males
Two or more X chromosomes in cells
47 XXY

14

How does FISH work

light chromosomes with dye - can look at one chromosomal region to see if there is deletion or duplication

15

what is mosaicism

when different cells have different genetic constitution

16

what is somatic mosaicism

when all cells suffer mutations

17

what is gondal mosaicism

of the 2 populations in the gonads, 1 population contains the usual genetic complement. The other contains a DNA mutation

18

what is the name given to cells that stop cells dividing if switched on

tumour suppressor

19

what is the name given to cells that start cells dividing if switched on

oncogenes

20

what is penetrance

the likelihood of disease if you have a gene mutation

21

what is the name given to diseases that segregate in families

mendelian disease

22

what are the types of DNA mutations

Wild type
Stop
Missense
Insertion
Deletion out of frame
Deletion in frame
Triplet expansion

23

what is a wild type mutation

typical form of a species as it occurs in nature i.e. the norm

24

what is a stop mutation

when the codon of the cell stops to early at the wrong point

25

what is a missense mutation

a point mutation where one nucleotide is swapped with another that has no affect on the following nucleotide order

26

what is a insertion mutation

an insertion of a single nucleotide that causes all the following nucleotide to shift to the right

27

what is a deletion out of frame mutation

a deletion of a single nucleotide that causes all the following nucleotide to shift to the left

28

what is a deletion in frame mutation

a deletion of more than one nucleotide that causes all the following nucleotide to shift to the left

29

what is a triplet expansion mutation

a duplication of three nucleotides that that causes all the following nucleotide to shift to the right

30

what is mendelian inheritance

change in a single gene causing disease

31

what are the types of mendelian inheritance

autosomal dominant, autosomal recessive, x-linked, mitochondrial

32

what are the chances of getting an autosomal dominant disease

50% chance if parent affected

33

what are the chances of getting an autosomal recessive disease

25% chance if parents are affected
need 2 faulty copies of the gene

34

what is an x-linked recessive disease

mutation in a gene on the X chromosome causes a disease in males e.g. haemophilia

35

what are females in X-linked diseases

carriers

36

what is a caveat

a female carrier that shows mild features of the disease

37

what is x-inactivation

in female cells only one x chromosome is active

38

what is a SNPs

a single nucleotide polymorphism; most have no effect

39

what is a CNV

a copy number variation - extra or missing stretch of DNA

40

what is the name given to variation in disease severity of you have the mutation

expression

41

what are the 4 types of non-mendelian inheritance

Multifactorial
Imprinting
Mitochondrial
Mosaicism

42

what is eczema linked with

filaggrin deficiency

43

what type of DNA does not transcribe

methylated DNA

44

where does methylation occur

at the cytosine bases just before guanine bases

45

what does methylation cause

modification of histones thus repressing transcription

46

what is imprinting

difference in gene expression depending on whether the gene is maternally or paternally inherited

47

what is angelman syndrome, how is it inherited and what is the name of this type of inheritance

when you don't have a working copy of the UBE3A gene on chromosome 15
UBE3A gene you get maternally
Paternal uniparental disomy

48

where are the checkpoints in the cell cycle

between G2 and M
between G1 and S

49

how is mitochondrial disease inherited

exclusively maternal

50

what is heteroplasmy

different daughter cells contain different proportions of mutant mitochondria

51

how do cells obtain somatic mosaicism

cells acquire mutations as they divide. Repair mechanisms exist to attempt to fix these mutations. The DNA repair is imperfect

52

what are the hallmarks of cancer

proliferation
evade immune response
acquire a vascular supply
avoid apoptosis
metastasis

53

what is the 2 hit theory

that both copies of the tumour suppressor gene are needed for cancer to occur

54

what is retinoblastoma

rare eye cancer in kids under 5

55

what is the mechanism for activation oncogenes

duplication of the gene
duplication of the gene promoter
change in amino acid sequence
phosphorylation of the gene

56

what is the low, medium and high risk of breast cancer according to the IceBreg model

Low - mother with breast cancer at 70
Medium - mother and sister with breast cancer at 45
High - BRCA1 mutation

57

what are the two types of gene testing

1 - symptomatic testing. Test for mutation after patient begins to have symptoms for the disease.
2 - Presymptomatic testing. Patient want to test if they have mutation that could lead to disease