Genetic technology Flashcards

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1
Q

what is genetic engineering (3)

A

removal of gene from one organism
transfer to another
so it can be expressed

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2
Q

what are the tools for genetic engineering

A

restriction enzymes

vectors

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3
Q

what is the role of restriction enzymes in bacteria

A

role is to restrict viral infection in bacteria - they recognise + break DNA from virus

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4
Q

describe restriction enzymes

A

enzymes bind to specific target site on DNA and cuts

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5
Q

what ways can restriction enzymes cut

A

straight ends = blunt ends

staggered fashion = sticky ends

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6
Q

what is unique about sticky ends

A

can hydrogen bond complementary to other bases of other DNA cut with same enzyme

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7
Q

examples of vectors (3)

A

plasmids
viruses
liposomes

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8
Q

how are plasmids prepared as vectors

A

bacteria treated with enzymes to break cell wall and spun in centrifuge
plasmids of circular DNA cut using same restriction enzyme

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9
Q

what is recombinant DNA

A

DNA made by joining pieces of different sources

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10
Q

why is recombinant DNA used (7)

A
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;
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11
Q

describe plasmids

A

small/circular piece of double stranded DNA;

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12
Q

why are plasmids used in gene technology (7)

A
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;
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13
Q

what are the ingredients for insulin production (4)

A

reverse transcriptase
DNA polymerase
restriction enzymes
DNA ligase

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14
Q

describe role of reverse transcriptase

A

make single strand of DNA from mRNA

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15
Q

describe role of DNA polymerase

A

link nucleotides by complementary base pairing to form double stranded DNA

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16
Q

describe role of restriction enzymes

A

cut plasmids at specific sites to create sticky ends

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17
Q

describe role of DNA ligase

A

seals sugar-phosphate backbone by adding a phosphate group

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18
Q

what are the three steps of insulin production

A

isolation of human gene
preparation of vector
formation of recombinant DNA

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19
Q

describe isolation of human gene (5)

A

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;

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20
Q

describe the preparation of vector (2)

A

plasmids extracted from bacteria;

same restriction enzymes cut to produce complementary sticky ends;

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21
Q

describe formation of recombinant DNA (6)

A

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;

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22
Q

what is electrophoresis of DNA

A

separating DNA by their size and charge

23
Q

how does electrophoresis work (6)

A
phosphate groups are negatively charged;
moves to anode;
due to electric field;
larger fragments move less distance;
buffer;
gel;
24
Q

what are the three factors in movement of molecules

A

net charge
size
composition of gel

25
Q

definition of the polymerase chain reaction (PCR)

A

rapid production of very large number of copies of fragment of DNA from a small quantity so fragments can be visible

26
Q

what are the ingredients for PCR (5)

A
target DNA
buffer solution
DNA primers
free nucleotides
taq polymerase
27
Q

describe taq polymerase (4)

A
produces complementary DNA strands;
heat stable;
does not need to be added again;
efficient;
75
28
Q

describe primers (3)

A

binds to DNA by complementary base pairing;
attaches close to specific section of DNA;
polymerase only attaches to DNA;

29
Q

describe the process of PCR (10)
95
65
75

A
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;
30
Q

what is the purpose of microarrays

A

finding which genes are expressed within cells

31
Q

how are genetically modified mice produced (5)

A
obtain allele;
microarray;
restriction enzyme;
used vector;
inject into zygote;
32
Q

describe the process of microarray (8)

A
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;
33
Q

how does genetic technology help humans

A

allows products specific to humans to be made

34
Q

example of genetically modified products for humans (3)

A

human growth hormone
thyroid stimulating hormone
factor VIII

35
Q

advantages of using bacteria (4)

A

simple nutritional requirements
large volume of product produced
don’t require much space
few ethical/practical problems

36
Q

disadvantages of using bacteria

A

doesn’t modify proteins in the way eukaroytes do

37
Q

what is genetic screening

A

analysis of person’s DNA for presence of particular allele

38
Q

how is the fetus genetically screened

A

one of the cell removed from fetus and DNA is analysed to predict whether embryo would have genetic disease

39
Q

ethics of genetic screening (7)

A
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;
40
Q

what is gene therapy

A

cure disorders by inserting normal alleles of these genes into cells

41
Q

describe the process of gene therapy (10)

A
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;
42
Q

which genetic disorder used liposomes/virus as vector

A

cystic fibrosis

43
Q

what is cystic fibrosis

A

genetic disorder which thick mucus produced in lungs and other parts of the body

44
Q

effects of cystic fibrosis patients (3)

A

prone to bacterial infections
need daily therapy
caused by recessive allele

45
Q

which vector for CF has short term effect

A

liposomes

46
Q

which vector for CF has side effects

A

virus vector

47
Q

what is germ cell therapy

A

inserting allele in egg and have it fertilised by sperm to form zygote - unpredicatable diseases + passed to generations

48
Q

ethics of gene therapy (3)

A

could increase number of abortions;
insurance/cost expensive;
success is not guaranteed;

49
Q

purpose of genetically modified plants (3)

A

produce vaccines
increase crop yield
improve nutrition

50
Q

effect of herbicide - resistant crops (4)

A

genetically modified plant willl become agriculture weed;
pollen will transfer to wild relative and produce hybrid offsprings;
weeds will evolve;
evolution of resistance;

51
Q

effect of insect - resistant crops (3)

A

evolution of resistance by insect pests;
damaging effect on other species of insects;
transfer of added gene to other species of plant;

52
Q

describe golden rice (pro-vit A)

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

53
Q

social implications using GMO in food production (6)

A

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;

54
Q

purpose of promoters

A

gene can be switched on so RNA polymerase can bind