genetic engineering

Question 1

BRCA1 and BRCA2 gene

Answer 1

produce tumour suppressor portions and when faulty increase chances of ovarian and breast cancer

Question 1

pros of genetic screening for people with family history BRCA1/2 gene mutations

Answer 1

a person may decide to take preventative measures like elective mastectomy
screening for breast cancer may start earlier to happen more frequently and the individual will have more frequent clinical examinations of the ovaries
person can participate in research clinical trials

Question 2

advantage of genetic screening for Huntington’s

Answer 2

gives people a chance to plan for the future- how they will live and be cared for
couple can make informed reproductive decisions ( their child will have a 50% chance of inheriting the disease)
people can participate in research and clinical trials

Question 2

huntingtons symptoms

Answer 2

lower cognitive ability and uncontrolled movements

Question 3

is Huntington dominant or recessive

Answer 3

dominant

Question 4

is cystic fibrosis (CF) dominant or recessive

Answer 4

recessive

Question 5

CF is a mutation in which gene

Answer 5

a gene that codes for a transported protein CFTR

Question 6

what is cystic fibrosis

Answer 6

a progressive disease that causes mucus in various organs to become thick and sticky. a common cause of death is bacteria infection in the lungs

Question 7

what does the mutation in the gene coding for the protein CFTR cause

Answer 7

CFTR no longer transports chloride ions across the cell plasma membranes so water does not move by osmosis across the membrane either. Water makes the mucus thinner enabling cilia to remove it

Question 8

advantage of genetic screening for CF

Answer 8

allows couples to make informed reproductive decisions (both may be carriers that do not display any symptoms)
people can participate in research and clinical trials

Question 9

7 advantages of using bacteria, yeast and cultures of mammalian cells to produce recombinant proteins like insulin factor VII and adenosine deaminase

Answer 9

production facilities do not require much space

process can be carried out anywhere in the world

More cost-effective to produce large volumes (i.e. there is unlimited availability)

Simpler (with regards to using prokaryotic cells)-simple nutritional requirements

Faster to produce many proteins
Reliable supply available

The proteins are engineered to be identical to human proteins or have modifications that are beneficial

It can solve the issue for people who have moral, ethical or religious concerns against using cow or pork-produced proteins
Insulin

Question 10

conjugation

Answer 10

transfer of genetic material from one bacterium to another

Question 10

how to make recombinant human insulin protein

Answer 10

Bacteria plasmids are modified to include the human insulin gene using restriction endonuclease and DNA ligase.
Plasmids are inserted into the bacterium Escherichia coli by transformation (bath of calcium ions then heat/electrical shock)

Once the transgenic bacteria are identified (by the markers), they are isolated, purified and placed into fermenters that provide optimal conditions
The transgenic bacteria multiply by binary fission and express the human protein - insulin, which is eventually extracted and purified

Question 11

transduction

Answer 11

gene transfer of genetic material form one bacterium to another via a virus

Question 12

How can you make recombinant cells producing facer VII

Answer 12

Kidney and voerman hamster cells have been genetically modified to produce Factor VII
The recombinant. cells a placed in a fermentor and cultured
due to the optimal conditions in the fermenter the hamster cells constantly express Factor VII which can be extracted purified and used as injectable treatment for haemophilia
Fewer ethical, moral or religious concerns (proteins are not extracted from human blood)
Less risk of transmitting infection (eg. HIV) or disease
Greater production rate

Question 13

what does adenosine deaminase do

Answer 13

it is an enzyme that breaks down deoxyadenosine which can be toxic to cells such as T-lymphocytes.

Question 14

how to make recombinant cells that produces ADA

Answer 14

The larva of the cabbage looper moth (Trichoplusia ni) has been genetically modified (using a virus vector) to produce the enzyme adenosine deaminase so that it can be used as a treatment whilst the patients wait for gene therapy or when gene therapy is not possible
Fewer ethical, moral or religious concerns (proteins are not extracted from cows)
Less risk of transmitting infection or disease (from cows)
More reliable production of the enzyme
Faster to produce many proteins

Question 14

what is SCID (serve combined immunodeficiency)

Answer 14

you have ADA (adenosine deaminase deficiency) and the immune system is damaged

Question 14

genetic screening

Answer 14

testing for an embryo foetus or adult to find out whether a particular allele is present

Question 15

possibilities of gene therapy

Answer 15

replace or inactivate a faulty gene or insert a new one

Question 15

gene therapy

Answer 15

treatment of a genetic disorder by inserting genetically corrected cells into the body or introducing functioning genes directly into affected cells

Question 16

what is Leber congenital amaurosis

Answer 16

a rare form of blindness

Question 17

non viral vectors

Answer 17

liposomes and ‘naked DNA’

Question 17

why are most gene therapies still in clinical trial stages

Answer 17

its hard to find delivery systems that can transfer normal alleles into a persons cell and ensure the gene is correctly expressed once there

Question 18

2 types of somatic gene therapy

Answer 18

Ex vivo – the new gene is inserted via a virus vector into the cell outside the body. Blood or bone marrow cells are extracted and exposed to the virus which inserts the gene into these cells. These cells are then grown in the laboratory and returned to the person by an injection into a vein In vivo – the new gene is inserted via a vector into cells inside the body

Question 19

SCID treatment

Answer 19

ex vivo somatic gene therapy During this therapy a virus transfers a normal allele for ADA into T-lymphocytes removed from the patient and the cells are then returned via an injection

Question 20

Why is SCID treatment not permanent

Answer 20

the T-lymphocytes are replaced naturally over time and therefore the patient requires regular transfusions every three to five months to keep their immune systems functioning

Question 21

why are retroviruses no longer used as vectors for scid treatment

Answer 21

retrovirus insert their genes randomly into a host’s genome which means they could insert the gene into another gene or into a regulatory sequence of a gene (which could result in cancer) Initial treatments did cause cases of leukaemia in children, so researchers switched to using lentiviruses or adeno-associated viruses as vectors

Question 22

difference between lentiviruses and adenosine-associated viruses

Answer 22

Lentiviruses also randomly insert their genes into the host genome however they can be modified to not replicate, whereas adeno-associated viruses do not insert their genes into the host genome and therefore the genes are not passed onto the daughter cells when a cell divides This is an issue with short-lived cells like lymphocytes but has not been a problem when used with longer-living cells such as liver cells

Question 23

treatment for leber congenital amaurosis

Answer 23

There is no cure for these diseases Using in vivo somatic gene therapy, doctors injected into the retina adeno-associated viruses that contained the normal alleles of one of the genes that caused damage to the photoreceptors All patients that have had the injections have shown improvement in their eyesight

Question 24

pre-implantation genetic diagnosis (PGD)

Answer 24

embryos that are created outside the body via IVF can have their DNA analysed allowing for embryos that are not carrying harmful allele to be chosen for implantation

Question 25

How can genetic screening lead to a miscarriage

Answer 25

due to the procedures used to collect DNA which are not 100% risk-free Amniocentesis – is used to obtain a sample of amniotic fluid using a hypodermic needle at 15 to 16 weeks of pregnancy Chorionic villus sampling – is used to obtain a small sample of the placenta using a needle between 10 and 13 weeks of pregnancy

Question 26

social and ethical considerations of using gene therapy

Answer 26

The potential for side effects that could cause death (e.g. the children who were treated for SCID developed leukaemia) The commercial viability for pharmaceutical companies – if it is a rare disease, the relatively small number of patients may not mean that the companies will make a profit The expense of treatments as multiple injections of the genes may be required if the somatic cells are short-lived (e.g. severe combined immunodeficiency) This may make the cost of gene therapy accessible to a limited number of people The possibility that people will become less accepting of disabilities as they become less common Who has the right to determine which genes can be altered and which cannot (e.g. should people be allowed to enhance intelligence or height) Another method of enhancing sporting performances unfairly through gene doping This is where the genes are altered to give an unfair advantage eg. to provide a source of erythropoietin (the hormone that promotes the formation of red blood cells) Test yourself

Question 27

structural genes

Answer 27

codes for a protein that has a role with in the cell

Question 28

transcription factors

Answer 28

proteins that bind o DNA and are involved in the control of the gene expression in eukaryotes by decreasing/increasing rate of transcription

Question 29

inducible enzyme

Answer 29

only synthesised when substrates their are present

Question 29

regulatory gene

Answer 29

codes for a protein that controls the expression of another gene

Question 30

repressible enzyme

Answer 30

synthesised as normal until a repressor protein bind to operator

Question 31

lac Z

Answer 31

codes for permeate gene that allows lactose to enter cell

Question 32

lac z

Answer 32

codes for B galactosidase which breaks lactose into galactose and glucose

Question 33

operon

Answer 33

functional unit of transcription. A cluster of genes that are controlled by the same promoter

Question 34

transcription factors in eukaryotes

Answer 34

responsible for determination of sex in mammals form part of protein complex that binds to the promoter region of the gene concerned development of baby in womb allow responses to environmental stimuli such as turning on right genes to respond to high temps regulate cell cycle

Question 35

how to TF affect development of baby in womb

Answer 35

ensure a number of different genes are activated in the correct sequence allowing correct pattern of development od boggy regions as a zygote becomes an embryo then feuds

Question 36

what is gas 9

Answer 36

an endonuclease that cuts DNA at a specific point determined by guide DNA (gRNA). Part of gRNA can locate and bind to complementary DNA. Cas9 is an enzyme with 2 active sites for both strands of DNA

Question 37

what is CRISPR

Answer 37

group of base sequences that code for a short length of RNA, they direct a nuclease enzyme (caS 9) towards a specific base sequence.

Question 38

pcr temps

Answer 38

denaturation 95 annealing 60 extension 72

Question 38

why do you use microarrays

Answer 38

identify genes present in organisms genomes and and out which are expressed study large number of genes in a short time

Question 48

Purpose of pcr

Answer 48

Amplify DNA/ produce many identical strands

Question 49

Purpose of primers

Answer 49

Short single strand of DNA that Binds to the start of a desired gene so that DNA polymerase enzyme can begin copying

Question 50

Why are VNTRs useful for carrying out genetic fingerprints

Answer 50

The length of VNTR varies between people only identical twins have the same lengths

Question 51

Vector definition

Answer 51

Carrier of DNA into another cell

Question 52

Where is human insulin mRNA extracted from

Answer 52

Human pancreatic cells

Question 53

3 reasons why use genetic engineering over selective breeding

Answer 53

organisms with the desired trait are produced more quickly all organisms will contain the desired characteristics (no chance recessive allele will arise in population the desired characteristic may come from a different species/kingdom

Question 54

gm salmon

Answer 54

gm to grow more rapidly by inserting a gene from chinook salmon with promotor gene from ocean pout so growth hormone is produced the whole year not just spring and summer

Question 55

how to prevent gm salmon form reproducing in the wild

Answer 55

only gm females and sterile salmon

Question 56

gm soybean

Answer 56

gene from agrobcterium that is herbicide resistant by allowing enzyme to produce amino acids that make proteins in growing tips. The herbicides inhibits the enzyme in plants without the resistant gene; without the proteins being synthesised, the plants die

Question 57

which 3 amino acids are made by enzymes form agrobacterium

Answer 57

phenylalanine, tyrosine and tryptophan

Question 58

gm maize

Answer 58

Maize has been genetically modified with a gene for the Bt toxin, which is taken from the bacterium Bacillus thuringiensis and produce their own insectiside When an insect ingests parts of the maize plant, the alkaline conditions in their guts activate the toxin (the toxin is harmless to vertebrates as their stomach is highly acidic), killing the insect Different strains of B. thuringiensis produce different toxins which are toxic to different insect species Insect populations have developed resistance to the genes for Bt toxin, reducing effectiveness as a means of protecting crops

Question 59

process of genetic screening

Answer 59

1.patient DNA is isolated 2.DNA is amplified using PCR 3.restriction endonuclease used to cut up DNA into smaller fragments 4.Fragments under go gel electrophoresis 5.Dna fragments transferred to Nylon membrane and probes added to sample 6.gel washed and UV shone

Question 60

2 techniques to obtain cells from a growing foetus to undergo genetic screening

Answer 60

amniocentesis chronic villus sampling

Question 61

why is gene delivery difficult to implement

Answer 61

difficulty inserting allele to replace faulty ones lack of suitable vector only short term relief