Using Genome Projects

Question 1

What is an SNP

Answer 1

Single nucleotide polymorphisms

Single base variations associated with a disease of disorder

Question 2

Why is it easier to deduce the proteome of a prokaryotes than a eukaryotes?

Answer 2

Prokaryotes have one, non histone associated circular DNA section without any introns - all portions are coding

Where as eukaryotic organisms have more non coding introns, histone associated, some genes are regulators,

Question 3

Describe the processes of isolation of a gene by reverse transcriptase

Answer 3

Reverse transcriptase converts RNA into DNA
Find cell that produces a lot of required protein
Add the reverse transcriptase
Reverse transcriptase forms single stranded complementary DNA
DNA polymerase acts to form double stranded DNA

Question 4

Describe isolation of gene with Restriction endonuclease

Answer 4

Bacteria produce restriction endonuclease
Which are Enzymes that cut up DNA (protect bacteria from viral infection)
May occur opposite each other - blunt ends
Or may be cut in a staggered line leaving sticky ends (often palindromic)

Question 5

Describe how you can make a gene with the gene machine

Answer 5

Find DNA sequence by working backwards from the protein structure
Feed the nucleotide sequence into a computer
Computer creates small overlapping single strands
Gene is replicated with PCR
Sticky ends allow insertion into a plasmid

Question 6

How are externally synthesised genes added back into the bacteria or organism?

Answer 6

Vectors - i.e. By inserting into a plasmid

Question 7

Describe the addition of a synthesised gene into the DNA of an organism

Answer 7

Restriction endonuclease produces DNA fragments with sticky ends
If you use the same endonuclease on the vector the sticky ends will be complementary.
Add promoter and terminator regions of DNA, they allow RNA polymerase and transcriptional factors to bind
introduce the plasmids - transformation. Make the bacterias membrane more permeable with temperature changes and calcium ions plasmids pass through

Question 8

Once you have added a gene into a bacteria how can you test which bacteria have taken it up using antibiotics ? What is a problem with this method?

Answer 8

Use a plasmid containing the antibiotic resistant gene (i.e. Produces a enzyme that breaks antibiotics down)
Grow bacteria in a medium full of antibiotics
Hence only those that have the plasmid will survive

However it is possible that this plasmid sealed before the gene was entered hence some bacteria will have the plasmid but without the gene

Question 9

Describe fluorescent markers as a means of detecting a gene

Answer 9

The plasmid used as a vector contains another gene that is fluorescent. Either gene insertion disrupts the fluorescence or it has another gene with it that causes it

Question 10

What is needed for PCR?

Answer 10

The DNA sequence to be copied
DNA polymerase
Primers
Nucleotides

Question 11

Describe the method used in PCR

Answer 11

Temperature raised to 95 degrees two DNA fragments separate as hydrogen bonds break
Temperature reduced to 55 degrees allows primers to anneal to the complementary DNA fragments ( primers prevent two stands rejoining) and provide the starting sequence for DNA polymerase to work on
DNA synthesis temeperture raised to 72 degrees as this is optimum temperature for DNA polymerase

Question 12

The process of PCR happens at a ever increasing rate hence it is _____________. Describe how this is so

Answer 12

Exponential
DNA strands produced can undergo synthesis and make more etc
Hence the sample is amplified

Question 13

Comapre in vivo to in vitro (PCR) cloning

Answer 13

In vitro is very fast, only needs a small sample and has no living cells so ethics is less complex
In vivo, enables the introduction of a gene, no risk of contamination as the restriction endonuclease is specific
Accurate

Question 14

Give some potential benefits to recombinant DNA technology

Answer 14

GMOs can produce treatments for disease
Controls pollution - microorganisms that destory gases etc
GM crops - more efficient growth
Gene therapy

Question 15

Describe the risk associated with DNA technology

Answer 15

Ecological risks and damage to balance in ecosystems
Viruses can transfer genes from organism to orgamism
Antibiotic resistance used as a marker increases antibiotic resistant
Designer babies etc

Question 16

Describe how gene therapy can work to tackle genetic diseases

Answer 16

Isolate gene ( reverse transcriptase/ reaction endonuclease gene machines)
Insert gene into a retro virus
Retro virus can inject a copy of gene into target cells

Question 17

Describe DNA probes, how are they made?

Answer 17

Short single stranded DNA sections with a label attached which may be radioactive or fluorescent
Obtain base sequence of the gene you want to identify
Make complementary probe
Amplify with PCR
Add split DNA to probe
Wash to remove unattached
Detect with xrays

Question 18

What is DNA screening?

Answer 18

Allows checking for cancer susceptibility, which enables people to make life choices to reduce their risk, and checking for bumps etc
Parents can be scanned to see if they are likely to pass anything on to their children
Provides info for personalised medication

Question 19

Describe gel electrophoresis

Answer 19

Put sample on an agar plate
Apply a voltage
Phosphate group on DNA gives DNA a negative charge so the fragments move towards the positive terminal
Shorter strands move further as the attraction to the plate is lesser

Question 20

What are VNTRs why are they vital for fingerprinting?

Answer 20

Variable number tandem repeats
Non coding DNA sections
No two individuals will have the same VNTR pattern