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Alevel Biology OCR > 6.1.3 - Manipulating Genomes > Flashcards

6.1.3 - Manipulating Genomes Flashcards

1
Q

What is a genome?

A

all of the DNA in an organism

  • from nucleus and mitochondria
  • human genome has 3.5 million base pairs in DNA
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2
Q

What is DNA sequencing?

A

working out the sequence of bases in a strand of DNA

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3
Q

What new developments have increased the speed of DNA sequencing/processing?

A
  • high throughput sequencing
  • shotgun sequencing
  • whole genome sequencing
  • next generation sequencing
  • pyrosequencing (using luciferase)
  • massive parallel sequencing
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4
Q

Why is gene sequencing important?

A
  • allows for genome-wide comparison between individuals and species
  • allows for sequences of amino acids in polypeptides to be predicted
  • allows for development of synthetic biology
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5
Q

What is bioinformatics?

A

the development of the software and computing skills needed to analyse and organise raw biological data
eg. development of mathematical models, statistical tests, algorithms, etc.

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6
Q

What is computational biology?

A

the study of biology using computational techniques to analyse large amounts of data
-uses data to build theoretical models of biological systems, which can be used to predict outcomes in different situations

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7
Q

What is genomics?

A

the field of genetics which applies DNA sequencing methods and computational biology to analyse the structure and function of genomes

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8
Q

How has gene sequencing allowed for genome-wide comparisons between individuals and between species?

A
  • computers can analyse and compare genomes
  • patterns in DNA inherited can be revealed
  • patterns in diseases we are vulnerable to can be revealed (aids medicine and epidemiology research)
  • aids identification of species (by comparison to a standard, eg. in DNA barcoding)
  • evolutionary relationships between organisms can be understood better
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9
Q

What is synthetic biology?

A

the design and construction of biological pathways, organisms or devises, or the redesign of existing natural biological systems

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10
Q

What techniques are considered a part of synthetic biology?

A
  • genetic engineering
  • synthesis of new genes to replace faulty genes
  • synthesis of a new organism
  • use of biological systems in industrial contexts (like using immobilised enzymes)
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11
Q

What is DNA profiling?

A

producing an image of the patterns in the non-coding DNA of an individual
-uses mini and micro satellites instead of genes

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12
Q

How is a DNA profile produced?

A
  • DNA is extracted (using a tissue sample)
  • sample is digested (broken down using restriction endonucleases to cut the DNA at specific points along the nucleotide sequence, known as restriction sites)
  • DNA fragments are separated (using electrophoresis)
  • hybridisation (DNA probes with radioactive or fluorescent markers are used to highlight important DNA sequences)
  • evidence is viewed (using images from DNA probes or sequencing data)
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13
Q

What are the uses of DNA profiling?

A
  • forensics
  • analysis of disease risk
  • paternity tests
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14
Q

What are restriction endonucleases?

A

enzymes which cut DNA at specific points (restriction sites) into smaller pieces

  • different enzymes cut at different sites
  • used in DNA profiling
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15
Q

What does PCR stand for?

A

polymerase chain reaction

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16
Q

What is the polymerase chain reaction (PCR)?

A

a process which amplifies a small sample of DNA

  • produces a large number of samples of the same section of DNA, which can then be used in further study
  • uses specific enzymes and temp changes
17
Q

What happens in the polymerase chain reaction (PCR)?

A
  • strands are separated (temp is increased to 95°C to denature the DNA by breaking the H-bonds between the complementary bases to separate the 2 strands)
  • annealing of primers (temp is decreased to 55°C and primers anneal/bind to the end of the sections of DNA that you want to amplify)
  • DNA synthesis (temp is increased to 72°C and free DNA nucleotides complementary base pair to exposed bases and Taq polymerase adds these bases onto the primer by forming phosphodiester bonds to produce a double-stranded sample of DNA identical to the desired sequence)
  • this is repeated to produce lots of samples of the desired sequence
18
Q

How are the strands of DNA separated in PCR?

A
  • temp is increased to 95°C

- DNA is denatures as the H-bonds between the complementary bases are broken

19
Q

How do primers anneal to DNA in PCR?

A
  • temp is decreased to 55°C

- primers anneal/bind to the end of the sections of DNA that you want to amplify by complementary base pairing

20
Q

How is DNA synthesised in PCR?

A
  • temp is increased to 72°C
  • free DNA nucleotides complementary base pair to exposed bases
  • Taq polymerase adds these bases onto the primer by forming phosphodiester bonds to produce a double-stranded sample of DNA identical to the desired sequence
21
Q

What temperature is required during PCR for the DNA strands to be separated?

A

95°C

22
Q

What temperature is required during PCR for the annealing of primers?

A

55°C

23
Q

What temperature is required during PCR for the synthesis of DNA?

A

72°C

24
Q

Why is Taq polymerase used in PCR rather than DNA polymerase?

A

Taq polymerase is extracted from thermophilic bacteria found in hot springs so is adapted to high temperatures (so won’t denature)

25
Q

What is electrophoresis?

A

a separation technique which uses electrical current to separate fragments of nucleic acids and proteins by size

26
Q

What are the uses of electrophoresis?

A

to separate nucleic acid fragments or proteins by size

27
Q

How is gel electrophoresis carried out?

A
  • pour agrose gel into gel tray and leave to solidify
  • place gel tray in a box and pour buffer solution over it
  • load DNA and dye into sample wells using a micropipette
  • put lid on gel box and turn on power supply
  • leave DNA samples to move through gel (towards +ve electrode)
  • remove the gel tray and add dye to the gel tray to stain the DNA fragments to view them
28
Q

What is genetic engineering?

A

the manipulation of an organism’s DNA

-isolating genes from one organism and placing them into another using vectors

29
Q

What is recombinant DNA?

A

DNA from two different sources

30
Q

How is genetic engineering carried out?

A
  • DNA fragment containing desired gene is isolated/extracted using restriction enzymes
  • DNA fragment is inserted into a vector using restriction enzymes and DNA ligase (recombinant DNA is produced) -this can be done by electroporation
  • the vector containing the recombinant DNA transfers the desired gene into the bacterial cell
31
Q

What vectors could be used in genetic engineering?

A
  • plasmids (transfer DNA into bacterial or yeast cells)
  • viruses (transfer DNA into human or bacterial cells)
  • liposomes (fuse with cell membranes to transfer DNA into cells)
32
Q

What is electroporation?

A

adding electrical current to a solution so that the cell receiving the vector/gene has a more leaky membrane so vector can enter

33
Q

Name some examples of genetic engineering

A
  • insect resistance in genetically modified plants
  • genetically modified pathogens for research
  • pharming (genetically modified animals to produce pharmaceuticals)
34
Q

What are the positive ethical issues relating to genetical engineering?

A
  • helps to cure disease by producing medicines
  • pest/disease/herbicide resistant crops increase the yield and reduce loss of crops and reduce the amount of pesticides sprayed
  • crops can grow in a wider range of conditions
35
Q

What are the negative ethical issues relating to genetical engineering?

A
  • scientists researching the pathogens could be infected and potentially cause a disease outbreak
  • in the wrong hands, knowledge about genetic engineering could be used in biowarfare
  • insects could become resistant to the pesticides in GM crops
  • transferred genes could spread to other plant populations and cause problems
36
Q

What is gene therapy?

A

altering a person’s genetic material to treat/cure a genetic disease

37
Q

What is somatic cell gene therapy?

A

gene therapy where the alleles in body cells (aka somatic cells) are altered

  • in particular the specific cells affected by the disorder
  • can be done by replacing a faulty gene with a healthy one
38
Q

What is germ line cell gene therapy?

A

gene therapy where the alleles in sex cells are altered

-offspring produced won’t inherit disease

39
Q

What are the differences between somatic cell gene therapy and germ line cell gene therapy?

A
  • alleles are altered in somatic cells vs in gametes
  • in germ line cell gene therapy, the offspring produced won’t inherit the disease (they inherit the gene therapy alterations) whereas in somatic therapy, they could

Alevel Biology OCR (26 decks)

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