C1 human genetic variaton

Question 1

locus

Answer 1

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

Question 2

DNA polymorphism

Answer 2

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

Question 3

size of polymorphism

Answer 3

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

Question 4

how do people get the majority of polymorphisms

Answer 4

old and passed down through generations

Question 5

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

Answer 5

rare varient
mutation

Question 6

what is a very rare mutation that has just appeared called

Answer 6

de novo

Question 7

4 types of polymorphic (mutant) DNA sequences

Answer 7

1. SNP
2. microsatellites
3. minisatellites
4. CNV

Question 8

what is a SNP

Answer 8

single nucleotide polymorphisms
seq change eg A to G

Question 9

what are microsatellites

Answer 9

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

Question 10

what are minisatellites

Answer 10

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

Question 11

what is CNV

Answer 11

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

Question 12

allele

Answer 12

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

Question 13

example of homozygous, heterozygous genotype

Answer 13

CC homozygous
CT heterozygous
TT homozygous

Question 14

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

Answer 14

highly repetitive DNA
middle repetitive DNA

Question 15

what is highly repetitive DNA

Answer 15

satellite DNA

Question 16

where is satellite DNA found

Answer 16

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

Question 17

example of satellite DNA

Answer 17

a-satellite DNA (alphoid)

Question 18

functions and repetitions of a-satellite DNA

Answer 18

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

Question 19

2 types of middle repetitive DNA

Answer 19

mobile DNA elements
tandem repeats

Question 20

what are mobile DNA elements

Answer 20

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

Question 21

2 types of mobile DNA elements

Answer 21

transposons
retrotransposons

Question 22

difference between transposons and retrotransposons

Answer 22

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

Question 23

(retro)transposon consequences

Answer 23

-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

Question 24

the 2 types of tandem repeats

Answer 24

microsatellites
minisatellites

Question 25

what are microsatellites/STRs also known as

Answer 25

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

Question 26

what are tandem repeats size

Answer 26

short units between 2 and 7 nucleotides

Question 27

what are minisatellites - VNTRs stand for

Answer 27

Variable Number Tandem Repeats VNTRs

Question 28

VNTR repeat size

Answer 28

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

Question 29

what do many micro-/mini-satellites show

Answer 29

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

Question 30

applications of polymorphisms

Answer 30

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

Question 31

what are restriction enzymes

Answer 31

bacterial enzymes

Question 32

what do restriction enzymes do in RFLPs

Answer 32

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

Question 33

how are restriction fragment sizes altered

Answer 33

by changes in or between enzyme recognition sites

Question 34

how do polymorphisms permit DNA fingerprinting

Answer 34

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

Question 35

when was DNA fingerprinting first applied

Answer 35

1985 alec jefferys originally used minisatellites (VNTRs0

Question 36

what is DNA fingerprinting now commonly used for

Answer 36

identify criminals paternity cases disaster body remains identification

Question 37

what methods are now used to for DNA fingerprinting

Answer 37

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

Question 38

what is amelogenin gene locus AMEL

Answer 38

a gene encoding a protein in tooth enamel

Question 39

what are the 2 alleles of AMEL

Answer 39

AMELX on X chr AMELY on Y chr

Question 40

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

Answer 40

PCR