topic 8 COPY

Question 1

How does determining genome of pathogen allow vaccines to be developed

Answer 1

Identify the genome proteome
So could identify potential antigens to use in vaccine

Question 2

Why can’t genome can’t be directly translated into the proteome in complex organisms

Answer 2

Presence on non coding dna
Presence of regulatory genes

Question 3

How are dna fragments produced using restriction enzymes

Answer 3

Restriction enzymes cut dna at specific base recognition sequences either side of desired gene
Shape of recognition site comp to active site
Many cut I’m staggered form = sticky ends

Question 4

How are dna fragments produced from mRNA

Answer 4

Isolate mRNA from cell that readily synthesise protien coded for by desired gene
Mix mRNA with dna nucleotides and RT and RT used mRNA as template to synthesise a single strand of cDNA
DNA polymerase can form second strand of dna using cDNA as template

Question 5

Adv of obtaining genes from mRNA instead of dna

Answer 5

Much more mRNA In cells making the protien than dna so easily extracted
mRNA introns already removed by splicing whereas dna contain introns
So can be transcribed and translated from prok that can’t removed introns from splicing

Question 6

Dna fragments amplified by PCR

Answer 6

Mixture heated at 95 to separate dna strands and break hydrogen bonds between bases
Mix cooled to 55 so primer can bind to dna fragment strand by forming hydrogen bonds between comp bases
Mix heated to 72 so nucleotides align next to comp exposed bases so DNA polymerase join adjacent dna nucleotides forming phosphodiester bonds

Question 7

Role of primers in PCR

Answer 7

Primers short single stranded dna fragments
Comp to dna base sequence at edges of region to be copied allowing DNA polymerase to bind to start synthesis
2 dif primers required

Question 8

In Vivo amplifying dna fragments

Answer 8

Add promoter and terminator regions to dna fragments
Insert dna fragments and marker genes into vectors using restriction enzymes and ligases
Transform host cells by inserting these vectors
Detect GM organisms by identifying those containing marker genes
Culture these transformed host cells allowing them to divide and from cloned

Question 9

Why are promoter genes added

Answer 9

Allow transcription to start by allowing DNA polymerase to bind to dna
Can be selected to ensure gene expression only happens in specific cell types

Question 10

Importance of terminator genes

Answer 10

Ensure transcription stops at the end of the gene by stoppimg rna polymerase

Question 11

Role of enzymes in inserting dna fragments using vectors

Answer 11

Restriction Endonucleases cut vector dna same enzyme used to cut gene out so vector and dna fragments have sticky ends that can join by comp base paring
Dna ligase join dna fragment to vector dna forming phodphodiester bonds between Adjacent nucleotides

Question 12

How are host cells transformed using vectors

Answer 12

Plasmids enter cell and viruses inject their dna into host cell which is then integrated into host dna

Question 13

Dna tech use in medicine

Answer 13

GM bacteria produce human proteins and its more ethical than using animal proteins and less likely to cause allergic reactions

Question 14

Gene therapy

Answer 14

Intro new dna into cells often containing healthy functional alleles
To overcome effect of faulty and non functional alleles in people with genetic disorders

Question 15

Issues with gene therapy

Answer 15

Effect short lived as modified cells have limited lifespan so require regular treatment
Immune response against GM cells or viruses due to recognition of antigens
Long term effects unknown side effects could cause cancer
Dna maybe inserted into other genes disrupting them and interfering with gene expression

Question 16

Dna probe

Answer 16

Short single stranded pieces of dna
With a base sequence comp to bases on parts of target allele usually labelled with fluorescent or radioactive tag for identification

Question 17

Dna hybridisation

Answer 17

Binding of single stranded dna probe to comp single strand of dna
Forming hydrogen bonds

Question 18

Genetic screening to locate specific alleles of genes

Answer 18

Extract dna and amplify PCR
Cut dna at specific base sequences using restriction enzymes
Separate dna fragments using gel electrophoresis
Transfer to a nylon membrane and treat to form single strands with exposed bases
Add labelled dna probes which hybridise and bind with target alleles and wash to remind unbound probe
To show bound probe expose membrane to uv light or autoradiography

Question 19

Gel electrophoresis

Answer 19

Method to separate nucleic acid fragments or proteins
According to length mass and charge

Question 20

Gel electrophoresis to separate dna fragments

Answer 20

Dna samples loaded into wells I’m a porous gel and covered in buffer solution
Electron current passed through dna is net charged so moves toward positive electrode
Shorter dna fragments travel faster and further

Question 21

How can gel electrophoresis results be interpreted

Answer 21

Run standard with dna fragments of known lengths under steamed conditions
Compare to position of unknown fragments
Shorter protiens travel further

Question 22

Uses of labelled dna probed

Answer 22

Screen patients for heritable conditions or drug responses or health risks

Question 23

What are VNTRS

Answer 23

Repeating sequences of nucleotides found within non coding sections of dna at many sites throughout an organisms genome

Question 24

VNTRS use in genetic fingerprint

Answer 24

Probability of two individuals habi g same vntrs low
As organisms genome contain many VNTRS and length at each loci differ between individuals

Question 25

Genetic fingerprinting to analyse dna fragments

Answer 25

Extract dna from sample and amplify by PCR
Cut dna at specific base sequences using restriction enzymes
separate VNTRS fragment according to length using gel electrophoresis
Transfer to nylon membrane and treat to form single strands with exposed bases
Add labelled dna probes why hybridise with comp VNTRS
To show bound probe expose membrane to uv or autoradiogrspny

Question 26

Genetic fingerprint and genetic seq compare

Answer 26

Both use PCR to amplify
Both due gel electrophoresis to separate dna fragments
Both use labelled dna probes
Fingerprinting VNTRS screening analyse specific alleles

Question 27

Forensic science

Answer 27

Compare genetic fingerprinting of suspects to genetic fingerprint of dna at crime science
Match meaning present at crime

Question 29

Recombinant dna tech

Answer 29

Transfer of dna fragments from organism to another

Question 30

Importance of genome sequencing

Answer 30

To identify dna base sequence of an organisms genome
So amino acid sequence of proteins that derive from an organisms genetic code can be determined