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bm210 biochemistry > C1 human genetic variaton > Flashcards

C1 human genetic variaton Flashcards

1
Q

locus

A

place/location in our genome
because we have 2 copies of almost every chr, locus usually refers to both
‘gene locus’

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2
Q

DNA polymorphism

A

an allelic form of sequence difference that is present in at least 1-2% of a pop

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3
Q

size of polymorphism

A

can be single nucleotide (SNP)
or thousands of bases
vary between chr and individual

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4
Q

how do people get the majority of polymorphisms

A

old and passed down through generations

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5
Q

what is it called if polymorphism is below 1-2% freq in a pop

A

rare varient
mutation

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6
Q

what is a very rare mutation that has just appeared called

A

de novo

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7
Q

4 types of polymorphic (mutant) DNA sequences

A
  1. SNP
  2. microsatellites
  3. minisatellites
  4. CNV
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8
Q

what is a SNP

A

single nucleotide polymorphisms
seq change eg A to G

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9
Q

what are microsatellites

A

short tandem repeats (=STR, SSR: simple sequence repeats, 2-7 bp=[CAG]n)

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10
Q

what are minisatellites

A

variable number tandem repeats (=VNTR, 8->50 bp= [CGT…TAG]n)

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11
Q

what is CNV

A

copy number varient
0, 1, 3 or more copies of a large stretch of DNA sequence (1000bp (1kb).Mb)

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12
Q

allele

A

term given to the specific DNA seq present at any polymorphic locus

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13
Q

example of homozygous, heterozygous genotype

A

CC homozygous
CT heterozygous
TT homozygous

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14
Q

repetitive DNA is often polymorphic
strings of A, T, C, G nucleotides repeating themselves in patterns
what are the 2 types

A

highly repetitive DNA
middle repetitive DNA

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15
Q

what is highly repetitive DNA

A

satellite DNA

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16
Q

where is satellite DNA found

A

in long tandem (end to end) strings or arrays
-near telomeres (ends of chr)
-around the centromeres (middle of chr)

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17
Q

example of satellite DNA

A

a-satellite DNA (alphoid)

18
Q

functions and repetitions of a-satellite DNA

A

functions in centromere of chr
repeats extend for millions of bp
each repear unit contains smaller repeat units between 4 and 32 bp

19
Q

2 types of middle repetitive DNA

A

mobile DNA elements
tandem repeats

20
Q

what are mobile DNA elements

A

‘viruses’ or ‘malware’ infecting genome
often encode proteins needed to cut them out, copy them and insert elsewhere in the genome

21
Q

2 types of mobile DNA elements

A

transposons
retrotransposons

22
Q

difference between transposons and retrotransposons

A

transposons= DNA based ‘LINE’, ‘SINE’, ‘Alu’
retrotransposons= RNA intermediate
‘LTRs’

23
Q

(retro)transposon consequences

A

-often polymorphic between individuals
-most inactivated throgh mutation/truncation over human evolution
-movement to new locus in only 1:100-200 births
-some inactivate genes eg GLO; vit C synthesis in humans now no longer possible

24
Q

the 2 types of tandem repeats

A

microsatellites
minisatellites

25
Q

what are microsatellites/STRs also known as

A

Short Tandem Repeats (STRs)
or
Simple Sequence Repeats (SSRs)

26
Q

what are tandem repeats size

A

short units between 2 and 7 nucleotides

27
Q

what are minisatellites - VNTRs stand for

A

Variable Number Tandem Repeats VNTRs

28
Q

VNTR repeat size

A

each repeat 8-100 bp long
repeated in tandem arrays up to 40 kilobases

29
Q

what do many micro-/mini-satellites show

A

show polymorphic variation in repeat number and hence variable length throughout the genome.. even in coding regions

30
Q

applications of polymorphisms

A

-RFLPs: (restriction fragment length polymorphisms)
-forensic sample identification
-biodiversity
-food quality
-ancestry/archaeology
-mapping of disease genes

31
Q

what are restriction enzymes

A

bacterial enzymes

32
Q

what do restriction enzymes do in RFLPs

A

act as primitive immune system.. cut ‘restrict’ a specific phage (viral) DNA seq
used as a molecular tool

33
Q

how are restriction fragment sizes altered

A

by changes in or between enzyme recognition sites

34
Q

how do polymorphisms permit DNA fingerprinting

A

techniques used to distinguish the unique combination of polymorphisms present in individual from another

35
Q

when was DNA fingerprinting first applied

A

1985 alec jefferys
originally used minisatellites (VNTRs0

36
Q

what is DNA fingerprinting now commonly used for

A

identify criminals
paternity cases
disaster body remains identification

37
Q

what methods are now used to for DNA fingerprinting

A

PCR based methods instead of restriction digests to obtain region of interest
and several single locus probes for minisatellites

38
Q

what is amelogenin gene locus AMEL

A

a gene encoding a protein in tooth enamel

39
Q

what are the 2 alleles of AMEL

A

AMELX on X chr
AMELY on Y chr

40
Q

what is used to amplify a segment of DNA in a part of the gene that shoes allelic size differences

A

PCR

bm210 biochemistry (19 decks)

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