Genetic technology Flashcards
what is genetic engineering (3)
removal of gene from one organism
transfer to another
so it can be expressed
what are the tools for genetic engineering
restriction enzymes
vectors
what is the role of restriction enzymes in bacteria
role is to restrict viral infection in bacteria - they recognise + break DNA from virus
describe restriction enzymes
enzymes bind to specific target site on DNA and cuts
what ways can restriction enzymes cut
straight ends = blunt ends
staggered fashion = sticky ends
what is unique about sticky ends
can hydrogen bond complementary to other bases of other DNA cut with same enzyme
examples of vectors (3)
plasmids
viruses
liposomes
how are plasmids prepared as vectors
bacteria treated with enzymes to break cell wall and spun in centrifuge
plasmids of circular DNA cut using same restriction enzyme
what is recombinant DNA
DNA made by joining pieces of different sources
why is recombinant DNA used (7)
can produce large quantities; product exactly same as human protein; product has same amino acid sequence; no immune response; no side effect; no risk of transfer in disease; easier to obtain purified product;
describe plasmids
small/circular piece of double stranded DNA;
why are plasmids used in gene technology (7)
replicate independantly; high copy number; easy to extract from bacteria; can be cut using restriction enzyme; gene can be inserted; taken up by bacteria; acts as vector;
what are the ingredients for insulin production (4)
reverse transcriptase
DNA polymerase
restriction enzymes
DNA ligase
describe role of reverse transcriptase
make single strand of DNA from mRNA
describe role of DNA polymerase
link nucleotides by complementary base pairing to form double stranded DNA
describe role of restriction enzymes
cut plasmids at specific sites to create sticky ends
describe role of DNA ligase
seals sugar-phosphate backbone by adding a phosphate group
what are the three steps of insulin production
isolation of human gene
preparation of vector
formation of recombinant DNA
describe isolation of human gene (5)
mRNA from B cells in pancreas extracted;
mRNA with code for insulin isolated;
reverse transcriptase uses mRNA as template to make single strand DNA;
single strand DNA → double strand DNA by DNA polymerase;
restriction enzyme cuts sticky ends on DNA;
describe the preparation of vector (2)
plasmids extracted from bacteria;
same restriction enzymes cut to produce complementary sticky ends;
describe formation of recombinant DNA (6)
insulin DNA + plasmids + ligase enzyme;
sticky ends bases form hydrogen bonds and DNA ligase seals sugar phosphate backbone;
recombinant DNA inserted back into bacteria;
gene is cloned by growing the bacterium;
bacteria produces insulin and grown on large scale;
extraction and purification of insulin;
what is electrophoresis of DNA
separating DNA by their size and charge
how does electrophoresis work (6)
phosphate groups are negatively charged; moves to anode; due to electric field; larger fragments move less distance; buffer; gel;
what are the three factors in movement of molecules
net charge
size
composition of gel
definition of the polymerase chain reaction (PCR)
rapid production of very large number of copies of fragment of DNA from a small quantity so fragments can be visible
what are the ingredients for PCR (5)
target DNA buffer solution DNA primers free nucleotides taq polymerase
describe taq polymerase (4)
produces complementary DNA strands; heat stable; does not need to be added again; efficient; 75
describe primers (3)
binds to DNA by complementary base pairing;
attaches close to specific section of DNA;
polymerase only attaches to DNA;
describe the process of PCR (10)
95
65
75
production of large number of copies; rapid; only small sample needed; DNA denatured at 95 degrees; primer added; annealing at 65 degrees; complementary base pairing; taq polymerase replicates strand at 75 degrees; taq polymerase is heat stable; does not need replacing; efficient;
what is the purpose of microarrays
finding which genes are expressed within cells
how are genetically modified mice produced (5)
obtain allele; microarray; restriction enzyme; used vector; inject into zygote;
describe the process of microarray (8)
mRNA extracted from cells; synthesise cDNA; tag with fluorescent dye; hybridised with probe; each probe unique to different gene; fluorescence indicates gene is expressed; complementary to DNA; UV light used to detect presence of DNA;
how does genetic technology help humans
allows products specific to humans to be made
example of genetically modified products for humans (3)
human growth hormone
thyroid stimulating hormone
factor VIII
advantages of using bacteria (4)
simple nutritional requirements
large volume of product produced
don’t require much space
few ethical/practical problems
disadvantages of using bacteria
doesn’t modify proteins in the way eukaroytes do
what is genetic screening
analysis of person’s DNA for presence of particular allele
how is the fetus genetically screened
one of the cell removed from fetus and DNA is analysed to predict whether embryo would have genetic disease
ethics of genetic screening (7)
allows people to prepare for condition; identify fetus condition; give early treatment; allow parents to prepare for birth of child who will need treatment through life; identify carriers; early diagnosis; termination;
what is gene therapy
cure disorders by inserting normal alleles of these genes into cells
describe the process of gene therapy (10)
normal allele; inserted into vector; liposomes as vector; short term effect; in aerosol; fuse with host cell; virus as vector; harmless; repeated treatments needed; side effects;
which genetic disorder used liposomes/virus as vector
cystic fibrosis
what is cystic fibrosis
genetic disorder which thick mucus produced in lungs and other parts of the body
effects of cystic fibrosis patients (3)
prone to bacterial infections
need daily therapy
caused by recessive allele
which vector for CF has short term effect
liposomes
which vector for CF has side effects
virus vector
what is germ cell therapy
inserting allele in egg and have it fertilised by sperm to form zygote - unpredicatable diseases + passed to generations
ethics of gene therapy (3)
could increase number of abortions;
insurance/cost expensive;
success is not guaranteed;
purpose of genetically modified plants (3)
produce vaccines
increase crop yield
improve nutrition
effect of herbicide - resistant crops (4)
genetically modified plant willl become agriculture weed;
pollen will transfer to wild relative and produce hybrid offsprings;
weeds will evolve;
evolution of resistance;
effect of insect - resistant crops (3)
evolution of resistance by insect pests;
damaging effect on other species of insects;
transfer of added gene to other species of plant;
describe golden rice (pro-vit A)
gene for production of carotene (makes vitamin A) inserted in plasmids with promoters
plasmids insert back into bacteria and mixed with rice embryos
rice embryoes grown in adult plants
social implications using GMO in food production (6)
modified crop plants invade natural habitats;
seeds are expensive;
need to be bought each season;
mofidied plants become hazardous - allergies;
herbicide leaves toxic residues in crop;
losing traditional varities with desirable background;
purpose of promoters
gene can be switched on so RNA polymerase can bind
