8.3,8.4

Question 1

genome

Answer 1

complete set of genes in a cell

Question 2

proteome

Answer 2

full range of protiens a cell can code for

Question 3

genome sequencing and its importance

Answer 3

identify dna base sequence of organisms genome
so AA seq of protein that derive from organisms genetic code can be determined

Question 4

Explain how determining the genome of a pathogen could allow vaccines to
be developed

Answer 4

could identify pathogens proteome
can identify possible antigens to put in vaccine

Question 5

other uses of genome sequencing projects

Answer 5

identify alleles associated with genetic Disorders
develop targeted drugs
screen patients for personalised medicine
identify species and evolutionary relationships

Question 6

why cant genome be directly translated to proteome in complex organisms

Answer 6

presence of Noncoding dna
presence of regulatory genes

Question 7

how are sequencing methods changing

Answer 7

automated
continuously updated

Question 8

Recombinant dna tech

Answer 8

transfer dna fragments from one organism to another

Question 9

dna fragment production by RE

Answer 9

RE cut dna at recognition sequence either side of desired gene
shape of recognition site comp to active site
many cut in staggered form (sticky ends)

Question 10

how can dna fragments be produced by mRNA

Answer 10

isolate mrna from a cell that readily synthesises protein coded for by desired gene
mix mRNA with dna nucleotides and RT
RT uses mRNA as template to synthesise single strand cDNA
DNA polymerase can use cDNA as a template to form a second strand of DNA

Question 11

2 advantages of obtaining genes from mrna rather than directly from dna

Answer 11

much more mrna in cells making protein than dna so its easily extracted
in mrna introns have been removed via splicing but dna contains introns
so can be transcribed and translated by prokaryotes who cant remove introns by splicing

Question 12

producing dna fragments from gene machine

Answer 12

amino acid sequence of protien determined so we can determine the base sequence
they dont contain introns so can be transcribed and translated by prokaryotes

Question 13

how can dna fragments be amplified by PCR

Answer 13

heat the mixture to 95 which
separates dna strands and breaks h bonds btwn bases
cool to 55 - allowing primer to bind to dna fragment template strand
by forming hydrogen bonds with complementary bases
mixture heated to 72
nucleotides align next to comp exposed bases
dna polm join adjacent nucleotides forming phosphodiester bonds

Question 14

primers role in pcr

Answer 14

primers are short singe stranded dna fragments
Complementary to dna base sequence at edges of region to be copied
allowing DNA polymerase to bind to start synthesis
two Dif primers are required as base sequences at ends are different

Question 15

in vivo amplifying dna fragments in vivo

Answer 15

add promoter and terminator regions to dna fragments
insert dna fragments and marker genes into vectors
using RE LIGASE
transform host cells by inserting these vectors
GM identified by those with marker gene
culture these transformed host cells and allow them to divide to form clones

Question 16

why are promoter regions added

Answer 16

allow transcription to start by allowing RNA polymerase to bind to DNA
can be selected to ensure gene expression only happens in specific cell types

Question 17

terminator regions

Answer 17

ensures transcription stops at end of gene by stopping RNA polymerase

Question 18

vector role

Answer 18

transfer dna into host cells

Question 19

role of restriction enzymes

Answer 19

RE cut vector dna
same enzymes used to cut gene out so vector dna and fragments have sticky ends that join by comp base pairing

Question 20

role of dna ligase

Answer 20

join dna fragment to vector dna
forming phosphodiester bonds between adjacent nucleotides

Question 21

how are host cells transformed using vectors

Answer 21

plasmid enters cell
virus inject their dna Inyo cells which is integrated into host dna

Question 22

why are marker genes inserted into vectors

Answer 22

identify GM
as not all cells take up the vector and become transformed

Question 23

use of recombinant dna tech in medicine

Answer 23

GM bacteria produce human protiens
more ethical than using animal protiens and less chance of allergic reaction
gene therapy

Question 24

use of RDT in agriculture

Answer 24

GM crops resistant to herbicides and insect attack

Question 25

gene therapy

Answer 25

introduction of new healthy alleles to overcome faulty non functional alleles in people with genetic disorders

Question 26

issues with gene therapy

Answer 26

short lived effect
immune response against GM bc recognition of antigens
long term effect unknown
dna inserted into other genes distupting them

Question 27

dna probes

Answer 27

short single stranded dna
with base sequence comp to bases on part of target allele
usually labelled with fluorescent or radioactive tag

Question 28

dna hydbridisation

Answer 28

binding of single stranded dna probe to complementary single strand of dna
forming hydrogen bonds

Question 29

genetic screening to locate specific alleles of gene

Answer 29

extract dna and amplify by PCR
cut dna at specific base sequence using RE
separate dna fragments using gel electrophoresis
transfer to nylon membrane and treat to form single strands with exposed bases
addd labelled dna probes which bind to target alleles
show bound probes..

Question 30

gel electrophoresis

Answer 30

separate nucleic acid fragments
according to length mass and charge
dna neg charged

Question 31

how to use gel electrophoresis to separate dna fragments

Answer 31

dna samples loaded into well in a porous gel and covered in buffer solution
electrical current passed through
dna is negatively charged so move towards positive electrode
short dna fragments travel faster snd further

Question 32

how can data showing results of gel electrophoresis be interpreted

Answer 32

run a standard with dna fragments of known lengths under same conditions
compare to position of unknown dna fragments
shorter dna fragments travel faster and further

Question 33

uses of labelled dna probes

Answer 33

screen patient for heritable conditions or drug response and health risk

Question 34

genetic counsellor

Answer 34

explain probability of a condition
lifestyle choices to reduce risks
treatments
explain results if genetic screening

Question 35

VNTRS

Answer 35

repeating sequence of nucleotides
found in non coding regions of dn at many sits thought an organism genome

Question 36

how are VNTRS useful in genetic fingerprinting

Answer 36

probability of two organisms having same VNTRS very low

Question 37

genetic fingerprinting to analyse dna fragments

Answer 37

extract dna from samply
amplify by PCR
cut dna at specific base sequence using RE
separate VNTR fragments according to length using gel electrophoresis
transfer to nylon membrane to treat and form single strands with exposed bases
add labelled dna probes which bind with comp VNTRS
show bond expose…

Question 38

genetic fingerprinting vs screening

Answer 38

both use pcr to amplify dna fragments
and gel electrophoresis and dna probes
GF - VNTRS
GS - SPECFIC ALLELES