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biology > 8.3 + 8.4 > Flashcards

8.3 + 8.4 Flashcards

1
Q

what are genome projects used for

A

determining the complete sequence of bases that make up the DNA of an organism

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2
Q

how to gene sequencing work

A

by cutting the DNA molecule into fragments which are sequenced and then they are put back into correct order to give the sequence of the whole genome

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3
Q

what can sequencing be used for

A

comparing genomes with species highlighting disease risk, improve understanding of inherited disorders and track early migration patterns with evolutionary relationships between species

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4
Q

what is the proteome

A

the sequence of proteins coded for by the DNA base sequence of the genome

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5
Q

what can finding the genome of simple organisms help with

A

intensifying antigens of viruses monitoring mutations as the pathogen evolves allowing us to produce vaccines faster controlling the spread of infection

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6
Q

why is it hard to determine the human proteome

A

as over 98% are introns (non-coding) so hard to determine which are exons

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7
Q

what are the three methods of making DNA fragments

A
  1. using reverse transcriptase to make cDNA
  2. genes can be found and ‘cut out’ using restriction enzymes
  3. Using a gene machine to build fragments
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8
Q

what can reverse transcriptase do

A

an enzyme that can convert RNA back into DNA

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9
Q

what does reverse transcriptase do in making DNA fragments

A

is is added using free DNA nucleotides to make DNA from the mRNA template which is called cDNA as it is complementary DNA matching the RNA

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10
Q

what do restriction endonuclease do

A

enzymes that can recognise and hydrolyse hydrogen bonds at specific sequences of DNA

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11
Q

what do restriction endonuclease do in making DNA fragments

A

they cut at a specific recognition sequence in the DNA which is complementary to their active site

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12
Q

what do restriction enzymes do

A

form sticky ends (pieces of DNA that have exposed nucleotides on a single strand at each end) allowing different fragments to be joined together

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13
Q

4 steps of using a gene machine to build DNA fragments

A
  1. the sequence is designed on a computer
  2. the first nucleotide in the sequence is attached to a physical support
  3. nucleotides are added step by step in the right order and joined in the correct place to prevent branching
  4. short sections of DNA called oligonucleotides are produced (20 nucleotides long). once these are complete they are broken off from the support and can be joined together to make longer fragments
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14
Q

what is the difference between in vivo and in vitro

A

vivo takes place in living organsims
vitro is not in living organisms translating to in glass

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15
Q

first step of in vivo

A
  1. desired gene is isolated using restriction endonuclease enzymess
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16
Q

second step of in vivo

A

promoter genes and terminator regions are added to the gene to make sure the gene can be correctly transcribed once in the host
- promotor tells RNA polymerase where to start and terminator tel RNA polymerase where to stop

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17
Q

third step of in vivo

A

the gene is inserted into a vector

cut the plasmid and the gene with same restriction endonuclease enzyme to leave ‘sticky ends’ allowing the target gene to fuse with the plasmid
ligase enzymes can join these two DNA fragments together by catalysing condensation reactions that join the sugar groups and the phosphate groups to the DNA backbone
when DNA fragments and plasmids are mixed not all plasmids will take up the gene correctly so DNA fragments that dont get inserted can also join its own sticky ends to create a loop

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18
Q

fourth step of in vivo

A

the recombinant plasmid is now transferred to host cells

a solution such as sodium chloride can be used to make cell walls more permeable, heat shock can be used or electroporation to make holes in membrane which DNA can pass through

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19
Q

step five in in vivo

A

the host cells are allowed to multiply and those that have successfully taken up the gene are identified using a marker gene

marker genes are inserted into vectors at the same time the gene is, these can code for antibiotics resistance and only transformed bacteria will survive.
as the genetic code is universal bacteria can transcribe DNA and translate the mRNA to produce the protein

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20
Q

what is PCR

A

the artificial replication of short sequences of DNA using artificial DNA primers to amplify a specific strand of DNA

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21
Q

what are the 4 steps of PCR (in vitro)

A
  1. the mixture is heated to around 95C to break the hydrogen bond between the complementary nucleotide base pairs and separate the double-stranded DNA into two single strands
  2. the mixture is cooled to around 55-60C so that primers can bind forming hydrogen bonds to one end of each single strand of DNA which identifies where tax polymerase should bind
  3. the temperature is raised to around 72C which is the optimum temperature for Taq DNA polymerase catalysing the addition of DNA nucleotides by complimentary base pairing to create two complete double strands of DNA
  4. repeat
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22
Q

what is the amount of DNA increase

A

exponential

23
Q

why does the number of fragments eventually plateau

A

as primers are the only thing used up in the reaction limiting the number of fragments that can be made. replication stops as they run out

24
Q

what are the three steps of genetic fingerprinting

A
  1. restriction enzymes are used to made DNA fragments that contain VNTRs these are amplified using PCR
  2. DNA fragments are separated by size using gel electrophoresis
  3. compare DNA fragments/proteins next to known samples
25
Q

what are VNTRs

A

variable number tandem repeats: repeating sequences that occur in different places in the genome of eukaryotes. the probability of two individuals having the same VNTR in the same place is very low meaning the length of VNTR between every person is unique

26
Q

how can genetic finger printing be used in medical diagnosis

A

testing to see if causes are genetic or identifying cancer

27
Q

how can genetic finger printing be used in forensic investigation

A

to establish w person present at a crime scene with PCR used to amplify trace amounts of DNA

28
Q

how can genetic finger printing be used in determining genetic relationships

A

paternity testing

29
Q

how can genetic finger printing be used in genetic variability

A

populations with similar genetic fingerprints have little diversity

30
Q

how can genetic finger printing be used in animal and plant breeding

A

identifying parents or genetic similarities can help selective breeding however increase genetic disorders

31
Q

What is a DNA probe

A

Single stranded pieces of DNA which are complementary to and therefore bind to known base sequences.

32
Q

4 uses of gene probes

A
  • locate specific alleles of genes
  • to see if a person carries a mutates allele that causes a genetic disorder such as cystic fibrosis
  • help determine how patients will respond to drugs such as breast cancer treatment which only responds to a certain mutation
  • identify health risks such as some peoples risk of cancer can be increased if they carry certain mutations
33
Q

method of gene probes (3 steps)

A
  1. DNA sample digested into fragments using restriction enzymes and separated using gel electrophoresis
  2. Separated DNA fragments transferred to nylon membrane and incubated with the DNA probe. The probes will only bind if the complementary sequence is present
  3. The membrane is exposed to UV light and if the gene is present it will fluoresce. DNA would be invisible without the probes so only bands which contain the gene will be visible
34
Q

what is a microarray

A

used to screen a sample with multiple DNA probes all at once

35
Q

how does a microarray work

A
  • the sample of fluorescent DNA is washed over the array which has the DNA probes fixed to it
  • DNA sequences that match the probe stick to the array
  • the array is washed to remove any fluorescent DNA not stuck to a probe
36
Q

what do genetic counsellors do

A

guide people to make informed decisions about matters related to genetics that may come up in their or their families health

37
Q

example of genetic counselling

A

screening for genetic mutations leading to cancers

38
Q

what does personalised medicine do

A

personalised medicine can be used target different dosages or compounds as medicine depending on the genetic make up of the person

39
Q

example of personalised medicine

A

some breast cancer treatments are targeted at specific mutations so screening can be used to make sure the right medicine is used

40
Q

what is gene therapy

A

the manipulation of the genetics of a human cell.

41
Q

what is somatic cells gene therapy

A

only affects certain cell types, the alterations made to the patients genome in those cells are not passed onto the patients offspring.

42
Q

method of delivering the functional alleles to the patients body cells: (4 steps)

A
  1. the liposomes are placed into an aerosol inhaler and sprayed into the noses of patients
  2. some liposomes will pass through the plasma membrane of the cells lining the respiratory tract
  3. some liposomes will then pass through the nuclear envelope and insert into the host genome
  4. the host cell will express the CFTR protein
43
Q

what are viral vectors

A

genetically engineered viruses used to deliver the functional gene copy

44
Q

why are viruses used as vectors

A

as they are already engineered to encapsulate and deliver genes to human cells to be transcribed and translated into proteins

45
Q

why is it a risk to used viruses as vectors

A

could be destroyed by the immune system, triggering an immune response the viral vector has potential to also reactivate its ability to cause disease

46
Q

what is germline gene therapy

A

altering the gamete or zygote of the organism changing the genetic make-up of the descendants of the original patient

47
Q

why is gremline gene therapy a risk

A

the gene may find their way to a location that could disrupt the expression or regulation of other genes or increase the risk of cancer

48
Q

ethical praises to do with animals (2)

A
  1. genetic manipulation is no different from crossbreeding
  2. genetic manipulation reduces cost and increase productions of crops
49
Q

ethical praises to do with plant (3)

A
  1. plant pathogen can reduce crop yield so getting rid of them helps famine
  2. reduces the cost and increase production of plant crops
  3. there is no evidence of any gene escaping crop plants into the wild
50
Q

ethical praises to do with bacteria (4)

A
  1. bacteria can be seen as little machines rather than parts of a larger ecosystem
  2. bacteria swap their DNA amongst themselves all the time
  3. many life saving drugs can be produced from genetically modified bacteria
  4. these bacteria can be completely isolated to the laboratory
51
Q

ethical issues to do with animals (3)

A
  1. animals are sentient
  2. genetic manipulation reduced the variation within the populations as clones are used
  3. there could be health implications for the animals
52
Q

ethical issues to do with plants (4)

A
  1. plants are harder to contain and could cross breed with wild varieties releasing new genes into the environment
  2. potential harm to human health from food
  3. negative impact on traditional farming practices
  4. excessive corporate dominance
53
Q

ethical issues to do with bacteria

A
  1. there is danger that they will escape from the lab
  2. there could be contamination from the other products of the bacteria
  3. antibiotic resistance genes are used and these could be create and untreatable pathogen as are carried on a plasmid that can be shared between species of bacteria
54
Q
A

biology (30 decks)

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