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A-Level Biology > 8B - Genome Projects and Gene Technologies > Flashcards

8B - Genome Projects and Gene Technologies Flashcards

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1
Q

When was the Human Genome Project completed?

A
  • 2003
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2
Q

How does sequencing the genome of simple organism help identify proteins and why is it useful?

A
  • proteome of an organism is determined by the base sequence
  • so if the base sequence is known then the proteome is known
  • this can be used to identify protein antigens on pathogens for antibiotic and vaccines
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3
Q

Why is it harder to translate the genome of complex organisms?

A
  • they contain non coding DNA and and regulatory genes, work is being done on the human proteome and more than 30000 human proteins have been identified
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4
Q

How are sequencing methods being updated?

A
  • there are being made more automated, cost effective and on a large scale such as pyrosequencing
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5
Q

What are the three ways of making DNA fragments?

A
  • using reverse transcriptase
  • using restriction endonucleases
  • using gene machines
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6
Q

How can DNA fragments be made from reverse transcriptase?

A
  • Most cells contain only two copies of each gene so it’s hard to locate and fragment each of those.
  • However there are lots of mRNA molecules which can be converted into complementary DNA via reverse transcriptase with complementary free DNA nucleotides after being isolated from the cell
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7
Q

How can restriction endonucleases be used to make DNA fragments?

A
  • Palindromic sequences of DNA are the same both ways in which they are read
  • Restriction endonucleases recognise these specific palindromic sequences and bind to them because they’re complementary to active site
  • then cut the recognition sequence at either side and leave sticky overhanging ends at each side which help them to bind to other DNA cut by the endonucleases (e.g. plasmids)
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8
Q

How do gene machines work?

A
  • contain a database w/ all the info needed to produce a DNA fragment (New fragments can also be designed).
  • first nucleotide is fixed to a support e.g. a bead
  • nucleotides are added step by step in correct order in a cycle of processes that includes adding protecting groups which ensure nucleotides are joined at the right point avoiding branching
  • short sections called oligonucleotides are produced which are joined together to make the desired fragment
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9
Q

What are the two types of DNA fragment amplification?

A
  • In Vivo amplification involving transforming host cells

- In vitro amplification involving polymerase chain reactions

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10
Q

What is the first stage in In Vivo Amplification?

A
  • A vector such as a plasmid has DNA cut open using the same restriction endonuclease as the fragment
  • this means the sticky ends can attach to each other in a ligation reaction which is catalysed by DNA ligase, forming recombinant DNA
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11
Q

What is the second stage in In Vivo Amplification?

A
  • vector then transfers the fragment into host cells
  • If vector is a plasmid it must persuade the host cell to take it up, calcium chloride solution makes cell walls more permeable
  • If it’s a bacteriophage vector, then it will infect the cell by injecting the DNA into it and this will be integrated into the host cell DNA
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12
Q

What is the third stage in In Vivo Amplification?

A
  • Only around 5% of DNA is taken up so marker genes such as UV or fluorescent markers or with antibiotic resistance
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13
Q

What is the fourth stage in In Vivo Amplification?

A
  • If you want to produce proteins in this amplification, you will also need to add promoter and terminator regions to the vector to ensure that RNA polymerase transcribes the DNA to make the protein
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14
Q

What is a host cell that takes up a vector DNA said to be?

A
  • transformed
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15
Q

Describe what a reaction mixture in PCR contains?

A
  • DNA sample
  • free nucleotides
  • primers
  • DNA polymerase
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16
Q

What is the purpose of primers?

A
  • stop DNA strands reattaching
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17
Q

Describe the process of PCR.

A
  • mixture is heated to 90°C to split the strands of DNA and cooled to 60°C so that the primers can anneal to the strands.
  • mixture is then heated to 72°C for DNA polymerase which joins free nucleotides to the strands via specific base pairing, then forms a polynucleotide along each complimentary strand
  • this is repeated over and over again. Doubling the amount each time
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18
Q

Describe how you could make recombinant DNA.

A
  • make a DNA fragment from restriction endonucleases
  • cut open plasmid, bacteriophage or host cell DNA w/ same enzyme
  • then insert that into the DNA so the sticky ends bind in a complimentary fashion.
  • then ligation occurs with the enzyme DNA ligase
19
Q

How are transformed plants made?

A
  • vector will be a plasmid
  • a gene for a desirable protein is put into this plasmid which is added to a bacterium which is used as a vector for a plant cell (promoter region is also needed)
20
Q

How can transformed animals be produced?

A
  • into the very early embryo vectors can be used to insert DNA into the DNA of the embryo so that DNA will exist in all of the animal cells
21
Q

Why are promoter regions important?

A
  • only cells where the gene will be useful have promoter regions
  • means that it can control where the gene is expressed
22
Q

Give examples of agricultural uses of recombinant DNA.

A
  • Crops can be made to have higher yields and be more nutritious with resistance to herbicides and pesticides
23
Q

Give examples of how recombinant DNA can be helpful to industry.

A
  • industrial processes involve enzymes which can be mass produced by transformed bacteria making it more cost effective
24
Q

How can recombinant DNA be used in medicine?

A
  • Drugs and vaccines can be produced on a mass scale by transformed bacteria such as the insulin production mechanism
25
Q

What are the concerns of using recombinant DNA in agriculture?

A
  • could lead to monoculture which leaves the whole crop vulnerable to disease with less biodiversity.
  • interbreeding between transformed plants and weeds could create super weeds and organic farmers could have crops contaminated by the recombinant seeds blowing into their farms so crops can’t be sold as organic
26
Q

What are the concerns of recombinant DNA in industry?

A
  • a few large biotech companies would control the forms of genetic engineering, forcing small businesses out of business
  • people won’t have a choice whether their products are recombinant DNA products
  • some consumer markets won’t import GM foods which can harm their business
27
Q

What are the concerns about recombinant DNA use in medicine?

A
  • Companies that own technologies could be limiting use of tech that could save lives
  • some worry it could be used unethically e.g. to create designer babies
28
Q

What other issues are there about recombinant DNA?

A
  • unclear who owns the genetic material created by recombinant DNA, is it the persons DNA or the scientists who changed it?
  • small nos. of large corporations own patents to particular seeds and can charge high technology fees to farmers
  • if their crops are contaminated by these seeds they can be sued
29
Q

How does gene therapy work?

A
  • involves altering defective genes inside cells
  • if allele is recessive then a functional dominant allele is inserted to supplement the faulty ones
  • if the allele is dominant then you can ‘silence’ allele by inserting DNA into the allele to stop it working
30
Q

How do you get the new allele inside the cell in gene therapy?

A
  • a vector is used such as viruses, plasmids or liposomes
31
Q

What are the two types of gene therapy?

A
  • somatic therapy

- germ line therapy

32
Q

What is somatic gene therapy?

A
  • altering alleles in body cells, particularly those most affected by the disorder
33
Q

What is germ-line gene therapy?

A
  • involves altering alleles in sex cells or embryos so any offspring will have the certain characteristics
34
Q

What is a gene probe?

A
  • short segments of DNA of a known sequence that are complimentary for a sequence you’re looking for
35
Q

What is hybridisation?

A
  • when a DNA probe bonds to a target allele if it’s present in a sample of DNA
36
Q

How is it possible to see if a DNA probe has hybridised?

A
  • if a label is attached to it e.g a radioactive label or a flourescent label
37
Q

Describe the process of looking for alleles using DNA probes.

A
  • sample of DNA is digested into fragments using restriction enzymes and separated using electrophoresis
  • separated fragments are transferred into a nylon membrane and incubated with a fluorescent labelled DNA probe
  • membrane is then exposed to UV light then it will become fluorescent
38
Q

Describe how a DNA microarray works.

A
  • DNA microarray is a glass slide containing lots of spots of different DNA probes attached to it in rows
  • then fluorescently labelled human DNA is washed over the array attaching to any complimentary probes
  • when a UV Light is shined over any labelled DNA will show and these are the alleles that are present
39
Q

What are the uses of DNA probes?

A
  • to see any inherited conditions
  • to see how a patient will respond to drugs
  • to help identify health risks
40
Q

How can screening results be used for genetic counselling?

A
  • if someone is identified to have certain health risks then they can take actions in their life to reduce this risks e.g. changes in diet, lifestyle and exercise
41
Q

How does personal medicine work and why is it useful?

A
  • genes determine how you respond to certain drugs
  • so if you know the genome then you can tailor drugs to DNA
  • more effective and less likely to be rejected
42
Q

What are variable number tandem repeats?

A
  • sections of DNA in the introns that have a sequence of bases repeating next to each other for a variable number for each person
43
Q

Describe how electrophoresis can be used to make genetic fingerprints?

A
  • A sample of DNA is taken, fragmented and amplified using PCR
  • VNTRs are all in the mixture now with different sizes. A fluorescent tag is then added to all the DNA fragments
  • there is a slab of gel covered in buffer solution that conducts electricity and current is passed through it
  • DNA is negatively charged because of the phosphate so they move towards the positive electrode
  • smaller ones move quicker creating a UV detectable pattern which can be compared to others
44
Q

Describe 5 ways in which genetic fingerprinting can be used.

A
  • determining relationships because you can compare possible family VNTRs because these are inherited
  • determining genetic variability as the more different the fingerprints are then the more variation
  • crime scenes can be used to compare fingerprints from DNA at the crime scene to suspects
  • medical diagnosis can involve unique patterns of several alleles which can be compared to fingerprints to see if your genome contains the alleles
  • genetic fingerprinting stops interbreeding in animals and plants which can be bad and lead to disorders

A-Level Biology (19 decks)

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