1
Q
what is synthetic biology
A
creation of artificial biological parts or redesigning of existing ones
2
Q
what is computational biology
A
using of computer-based techniques like computational models, large datasets, and bioinformatics to understand biological processes
3
Q
what is bioinformatics
A
using software to analyse biological data like DNA sequences
4
Q
enzymes used in isolating genes
A
- reverse transcriptase
- restriction endonuclease
5
Q
reverse transcriptase
A
makes complimentary DNA (cDNA) using an mRNA sequence
6
Q
restriction endonuclease
A
cuts DNA on the sugar-phosphate backbone at a specific base sequence
7
Q
restriction site
A
place where DNA is cut by restriction endonuclease
8
Q
palindrome sequence
A
restriction sites are cut in a staggered ‘palindromic’ way
9
Q
What is gel electrophoresis?
A
Used by scientists to sort DNA strands according to length
10
Q
What acts as a filter in gel electrophoresis
A
The gel - it acts as a sponge with small holes in it
11
Q
What is agarose
A
A dried powder made of seaweed
12
Q
What role does the electric current play in gel electrophoresis
A
Makes DNA move
13
Q
Which direction do DNA fragments migrate in gel electrophoresis
A
From the negative pole to the positive pole
14
Q
In what order do DNA fragments migrate towards positive pole
A
Shorter fragments move through holes in gel move quickly than long strands
15
Q
What is the purpose of the loading buffer in gel electrophoresis
A
Lets electrical charges flow through the gel
16
Q
What is the name of the holes that DNA is loaded into
A
Wells
17
Q
What does the ‘DNA size standard’ contain
A
DNA strands of known length
18
Q
How do you know when the current is running gel electrophoresis
A
Air bubbles come out of electrodes at both ends of electrophoresis box
19
Q
What is used to stain DNA and why in gel electrophoresis
A
- Ethidium bromide
Binds to DNA and shows up under fluorescent light
20
Q
Why is it important to avoid contact with ethidium bromide
A
Binds to DNA and damages cells
21
Q
What is polymerase chain reaction
A
Used to amplify (clone) DNA samples
22
Q
Thermocycler
A
Adjusts temperature during PCR
23
Q
Primer
A
Short sequences on DNA that are complementary to the bases at the start of the region to be copied
24
Q
Taq polymerase
A
DNA polymerase that can survive at high temperatures (thermophile, lots of disulphide bonds so lots of cysteine)
- globular protein
- water soluble because they have high proportion of R groups on amino acids which are hydrophilic
25
What are the 3 stages of PCR
1. Denaturation
2. Annealing
3. Extension
26
Denaturation
At 92°C DNA strands are separated by DNA helicase breaking H bonds
27
Annealing
At 55°C primers attach to DNA, act as starter sequence of double stranded DNA for polymerase, keeps DNA strands separated by preventing reformation of H bonds
28
Extension
At 72°C, Taq polymerase extends the sequence by joining free nucleosides in phosphodiester bonds, 2 chains produced by semi-conservative replication
29
what is DNA profiling
technique used by scientists to distinguish between individuals of the same species using only DNA samples
30
what are the main stages of DNA profiling
1. extraction
2. digestion with restriction enzymes
3. gel electrophoresis
4. southern blotting
5. DNA hybridisation with probes
6. development
31
stage 1 extraction
cells from blood, hair, saliva or semen extracted
32
stage 2 digestion with restriction enzymes
DNA is cut into fragments by restriction endonuclease
33
stage 3 gel electrophoresis
measures the length and amount of repeats in DNA fragments which differs between each person
34
stage 4 southern blotting
- gel immersed in alkali to seperate double strands into single strands
- single stranded DNA transferred to nitrocellulose paper or nylon membrane
- membrane covered with absorbent paper
- draws alkaline solution containing DNA through membrane via capillary action
35
stage 5 DNA hybridisation with probes
probes with a complementary base sequence to core sequences bind with the known single-stranded satellites
36
DNA probe
short single stranded section of DNA with a marker (radioactive or fluorescent)
37
stage 6 development
radioactive probes: photographic film placed over nylon membrane, radioactivity develops certain bands of film and this makes a photographic copy of the DNA band
fluorescent probes: use UV light to view DNA band
38
what is the sanger method of DNA sequencing
chain termination method that finds the order of nucleotide sequences
39
what is stage 1 of the sanger method of DNA sequencing
DNA sample, radio-labelled primer, free DNA nucleotides and DNA polymerase are mixed in 4 four tubes
40
what is stage 2 of the sanger method of DNA sequencing
- a modified dideoxynucleotide is added which cannot form a phosphodiester bond
- prevents further addition of bases to a DNA strand so DNA synthesis stops
- DNA fragments of different lengths are formed
41
what is stage 3 of the sanger method of DNA sequencing
- DNA synthesis takes place in test tubes
- binding of normal or terminator protein equally likely so DNA synthesis can be terminated at any point
- all fragments in one test tube will end in same nucleotide
- fragments can be identified as the primer is labelled radioactivley/fluorescently
42
what is stage 4 of the sanger method of DNA sequencing
- contents from tubes run side by side using gel electrophoresis, shortest fragments migrate the furthest
- fragments now sorted by length so read backwards from shortest from longest = corresponds with original DNA sample
43
how are recombinant organisms made
by transferring a desired gene from one organism to another
44
what role do vectors play in genetic engineering
carry a gene from organism to organism
45
example of recombinant organism
bacteria that make insulin
desired gene transferred to bacterial cells via their plasmid
46
what are the key stages of producing recombinant plasmids
1. isolation
2. recombination
3. transformation
4. identification
47
isolation in producing recombinant plasmids
- to isolate insulin gene, mRNA of the desired gene and reverse transcriptase are used to form a cDNA strand (DNA polymerase forms phosphodiester bonds)
- free DNA nucleotides are added to produce double stranded DNA
- restriction endonuclease then cuts both the DNA fragment with the desired insulin gene and the plasmid so they have complementary sticky ends
48
recombination in producing recombinant plasmids
- the complementary sticky ends of the vector and foreign DNA fragment anneal and are mixed with DNA ligase
- DNA ligase forms phosphodiester bonds in the backbone to make recombinant DNA
49
transformation in producing recombinant plasmids
plasmids are reintroduced back into bacterial cells by either:
- calcium chloride solution and heat shock
- electroporation
- electrofusion
50
calcium chloride solution and heat shock
- bacteria treated with a calcium chloride solution and heat shock which alters cell walls and makes them permeable to plasmids
- bacteria are incubated with the plasmids
- only some of the bacterial cells will take up the recombinant plasmids to become recombinant bacteria
51
electroporation
high voltage applied to cell which puts holes in cell membrane
52
electrofusion
electrical fields introduce plasmids to cells
53
identification in producing recombinant plasmids
replica plating is used to identify recombinant plasmids
54
replica plating process
- bacteria colony is first grown on a master plate of ampicillin
- if it grows on the ampicillin it means the plasmid is present
- sterilised velveteen surface is pressed on master plate to form an imprint
- transferred to a new plate of tetracycline
- if it grows on tetracycline the target gene is not present
55
how can GM plants be produced?
1. plasmid cut open using restriction endonuclease
2. desired gene cut using the same restriction endonuclease to produce complementary sticky ends
3. DNA ligase joins complementary sticky ends
4. transformation as plasmid is inserted into bacteria
5. bacteria infects plant cells and inserts desired gene into chromosome
6. plant cells grown in culture
7. plant generated from cell clone, all cells carry foreign gene to be expressed
56
how are animals genetically modified
somatic cell transfer
57
process of somatic cell transfer to produce spider silk protein
1. silk gene taken out of spider DNA
2. the first goat's body cell is enucleated
3. silk gene and nucleus are fused together via insertion
4. the second goat's egg cell is enucleated
5. the fused nucleus/silk gene are implanted into the enucleated egg cell
6. electric shock used to stimulate fusion and fertilisation, then mitosis occurs
7. embryo formed and implanted in the uterus of a third goat
8. this goat gives birth to a transgenic goat almost identical to the first goat
9. transgenic goat's milk is taken and spider silk removed from it
58
why is GM of microorganisms done
adenoviruses can be genetically altered to act as vectors in gene theray - ideal as they aren't cell/species specific so can infect many mammals with desired desired genes
59
why is GM of plants done
insect resistant soya bean plants developed as soya beans are very susceptible to insect pests which causes large losses in revenue for farmers
60
pharming
genetically modifying livestock to produce pharmaceutical drugs
61
why is pharming (GM of animals) done
biopharm animals can be used to produce lots of useful human proteins in their milk
62
positive ethics of GM of microorganisms
- can aid in research into developing effective vaccines/drugs
- can save lives in gene therapy by insertion of beneficial genes
63
negative ethics of GM of microorganisms
- changing viral genomes could result in a new virus for mammals should it escape the lab
- mutations may occur in inserted genes leading to unwanted effects in microorganisms
64
positive ethics of GM in plants
- increases productivity and yield
- could reduce impact of farming in environment as less need to spray pesticides
65
negative ethics of GM in plants
- insect populations can develop resistance to Bt toxin genes so it is less effective for protecting crops
- could decrease biodiversity as insect numbers decreasing can impact food web
66
positive ethics of GM animals
- desired genes/drugs produced quickly
- meets global demand for medicine, especially in LICs
67
negative ethics of GM animals
- ethical concerns with harming animals for research, reduced quality of life
- moral, ethical and religious concerns with using cows, pigs and goats
68
gene therapy
method used to treat genetic diseases by inserting functional allele to mask effect
69
somatic cell gene therapy
body cells, regular transfusions of desired gene every 3-5 months
ex vivo = new gene inserted via virus vector into cell outside of body, then injected
in vivo = new gene inserted via vector into cells inside the body
70
germ-line gene therapy
ILLEGAL
- desired allele inserted into gametes/early embryo (in vivo), all cells then contain desired allele
- can be passed onto offspring, potentially permanent
ocr a biology 🧬
flashcards
Decks in class (25)
# Cards
-
2.1.1 cell structures39
-
2.1.2 biological molecules59
-
2.1.3 nucleotides and nucleic acids23
-
2.1.4 enzymes15
-
2.1.5 biological membranes25
-
2.1.6 cell division39
-
3.1.1 exchange surfaces38
-
3.1.2 transport in animals50
-
3.1.3 transport in plants28
-
4.1.1 communicable diseases and the immune system65
-
4.1.2 biodiversity34
-
4.2.2 classification and evolution26
-
5.1.1 - communication and homeostasis24
-
5.1.2 excretion15
-
5.1.3 neuronal communication21
-
5.1.4 hormonal communication0
-
5.1.5 plant and animal responses0
-
5.2.1 - photosynthesis29
-
5.2.2 respiration5
-
6.1.1 cellular control48
-
6.1.2 patterns of inheritance35
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6.1.3 manipulating genomes70
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6.2.1 cloning and biotechnology0
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6.3.1 ecosystems0
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6.3.2 populations and sustainability0
