DNA sequencing and genomes

Question 1

describe difference between deoxyribonucleoside triphosphate and dideoxyribonucleoside triphosphate. effect of this difference?

Answer 1

dideoxy is missing OH on 3’ carbon. since the OH is required for condensation polymerisation, the chain wont extend.

Question 2

describe how strands are first made during the chain termination method

Answer 2

DNA synthesised - requires polymerase, requires deoxyribonucleoside triphosphates AND dideoxyribonucleosie triiphosphate.
dides can replace de’s randomly. leads to random chain termination

Question 3

describe how dna strrands are sequenced during chain termination method.

Answer 3

strands separated separate per A/T/C/G; from this we can sequence it

Question 4

modifications to chain termination method?

Answer 4

giving the dideoxyribonucleoside triphosphate a fluorescent tag; doing column electrophoresis and putting laser through i
performing reaction in single tube/separating fragments in a single lane.

Question 5

describe primer walking

Answer 5

important as chain termination method only works for short segments
one the end of a segment is polymerised and sequenced, you add primer to keep it oing.

Question 6

describe shotgun sequencing

Answer 6

multiple copies of a genome are cut up with restriction enzymes
sequenced to chain termination method
overlaps enable sequencing of whole genome

Question 7

describe two ways in which we can determine function of genes?

Answer 7

comparative genomics - model organisms, critical genes being conservd (eg. cytochrome C)
genetics/biochemistry: mutation analysis

Question 8

applications of the human genome project?

Answer 8

identify genes causing gene
making product: isolate and amplify gene, mass produce gene for pharmaceuticals
compare genomes of different species/tribes