1. genome projects and making DNA fragments

Question 1

genome

Answer 1

entire set of DNA (all genes) of an organism

Question 2

if you want to sequence an entire genome

Answer 2

you need to use DNA fragments (DNA chopped into smaller pieces)
smaller pieces are sequence then put back in order to give entire sequence

Question 3

proteome

Answer 3

all the proteins made by an organism

Question 4

determining proteome from genome

Answer 4

harder for complex organisms - coding and non coding DNA and complex regulatory genes (when gene switched on and off)
easer for simple organisms e.g. bacteria - dont have much non-coding DNA

Question 5

why is determining proteome useful

Answer 5

medical research and development
e.g. identifying protein antigens on surface of disease causing bacteria and virus - help in development of vaccines to prevent disease

Question 6

sequencing methods in the past

Answer 6

labour-intensive
expensive
small scale

Question 7

sequencing methods now

Answer 7

automated
cost effective
large scale
whole genomes can be sequenced much quicker

Question 8

recombinant DNA (transferring a fragment from one organism to another)
why is it possible

Answer 8

genetic code is universal
transcription and translation mechanisms similar
DNA can be used to produce protein in cells of recipient organism (known as transgenic organism)

Question 9

producing DNA fragment

using reverse transcriptase

Answer 9

1. lots of mRNA molecules complimentary to gene - easier to obtain
2. mRNA molecules used as templates to make lots of DNA.
3. enzyme reverse transcriptase makes DNA from RNA template cDNA (complimentary DNA)
4. mRNA isolated, mixed with free DNA nucleotides and reverse transcriptase

Question 10

producing DNA fragment

using restriction endonuclease enzyme

Answer 10

1. restriction endonuclease recognise specific palindromic sequences known as recognition sequences. cut/ digest DNA
2. different restriction endonuclease cut at different specific recognition sequences (because complimentary to active sit)
3. recognition sequence present at either side can use restriction endonuclease to separate it from rest of DNA
4. DNA sample incubated with restriction endonuclease which cuts DNA via hydrolysis
5. sometimes leaves sticky ends

Question 11

palindromic sequence of nucleotides

Answer 11

antiparallel base pairs / read same in opposite directions
GAATTC
CTTAAG

Question 12

sticky ends

Answer 12

small tails of unpaired bases at each end of fragment

can be used to bind/anneal DNA to another fragment with complimentary sticky ends.

Question 13

producing DNA fragment

using gene machine

Answer 13

synthesised from scratch no need for DNA template
database contains necessary info to produce fragment
any sequence can be made
1. sequence is designed
2. 1st nucleotide is fixed to support
3. nucleotides added step by step in correct order. includes adding protecting groups (make sure nucleotides joined at right points
4. short sections called oglionucleotides formed. broke from support and protecting groups removed. can be joined to form larger DNA fragments