1
Q
What is biotechnology?
A
The use of microorganisms to make practical products
2
Q
What is recombinant DNA technology?
A
Genetic engineering
3
Q
Describe donors and recipients in the context of genetically modified organisms (GMOs) (2)
A
- Genes are isolated from a donor organism
- Genes are inserted into the genome of a recipient organism
4
Q
What was the first drug manufactured using recombinant DNA technology?
A
Insulin
5
Q
What is reverse transcription?
A
Synthesis of RNA into DNA
6
Q
Retroviruses carry their genome as ______
A
RNA
7
Q
Reverse transcriptase is a ______
A
DNA polymerase enzyme
8
Q
What is the function of reverse transcriptase?
A
Synthesis of cDNA from an mRNA template
9
Q
How is complementary DNA (cDNA) made?
A
Through reverse transcriptase
10
Q
How are restriction enzymes produced?
A
Bacteria cut DNA at restriction sites
11
Q
What characteristics make restriction enzymes ‘restriction endonucleases’? (2)
A
- Recognizing palindromic sequences
- Restricting bacteriophages from multiplying
12
Q
Restriction sites are specific nucleotide sequences called ______
A
Palindromes
13
Q
Why do bacteria produce restriction enzymes in nature?
A
To stop bacteriophages from multiplying
14
Q
Describe EcoRI restriction enzymes (2)
A
- Make staggered cuts of 2 strands of DNA
- Create sticky ends
15
Q
Describe Hindlll and Smal restriction enzymes (2)
A
- Cut both strands of DNA at the same point
- Create blunt ends
16
Q
It is more difficult to make recombinant DNA from ______ fragments
A
Blunt-ended
17
Q
What are vectors in the context of recombinant DNA technology?
A
Nucleic acid molecules
18
Q
What are some examples of nucleic acid vectors? (2)
A
- Viral genomes
- Plasmids
19
Q
What selectable marker gene do vectors contain?
A
Antibiotic resistance gene
20
Q
How does the selection for vectors work? (2)
A
- A medium contains the antibiotic
- Cells containing the recombinant plasmid can grow on the medium
21
Q
What is the goal of recombinant DNA?
A
Insert a useful gene into a cell to get a new phenotype
22
Q
What are ‘CRISPR’s? – what does the acronym stand for?
A
- Clustered
- Regularly
- Interspaced
- Short
- Palindromic
- Repeats
23
Q
CRISPR DNA sequences act as a ______
A
Primitive immune system
24
Q
CRISPR DNA sequences provide protection from ______ from viruses
A
Prokaryotes
25
What are CRISPR repeats?
Stretches of palindromic DNA
26
How long are CRISPR repeats?
25 - 50 bp long
27
What are CRISPR spacers?
Sequences from viruses that invaded the prokaryote
28
How long are CRISPR spacers?
20 - 80 bp long
29
Describe the process in which bacteria acquire DNA sequences (2)
- A bacteriophage infects the cell
- A piece of viral DNA is added as a spacer
30
Describe the process in which CRISPR RNAs (crRNAs) mediate defense against viral infections (2)
- The spacer is transcribed into crRNA
- crRNA guides Cas to the bacteriophage
31
What specific role do CRISPR-associated enzymes (Cas) play in the defense against pathogens / future diseases?
Disables the virus by cutting its DNA
32
Describe how CRISPR technology can be used in so-called ‘genome editing’
RNA identifies a specific piece of DNA that is inserted into a new strand
33
By whom, and in what year, was the polymerase chain reaction (PCR) developed?
Kary Mullis in 1983
34
Name the 3 steps that make up one cycle of a typical polymerase chain reaction
- Denaturation
- Annealing
- Extension
35
Describe the denaturation step of the polymerase chain reaction (3)
- Double-stranded DNA is heated to 95°C
- Hydrogen bonds break
- Single-stranded templates are produced
36
Describe the annealing step of the polymerase chain reaction (2)
- Temperature is lowered to 45°C
- Primers anneal to the single-stranded template
37
Describe the extension step of the polymerase chain reaction (2)
- Temperature is heated to 72°C
- DNA polymerase synthesizes new strands
38
Regarding PCR, what are primers?
Short fragments of single-stranded DNA
39
Primers are ______ to known sequences
Complementary
40
How long are primers?
20 nucleotides long
41
In PCR, primers replicate ______ of a cell's DNA
A segment
42
In normal DNA replication, primers replicate ______ of a cell's DNA
All
43
What are the functions of deoxyribonucleotide triphosphates (dNTPs) in PCR? (2)
- Expand the growing DNA strand
- Bind with the cDNA strand
44
At the end of one cycle of PCR, how many new double-stranded DNA molecules are produced for each original molecule of target DNA?
2
45
At the end of one cycle of PCR, the amount of target DNA ______
Doubles
46
Does PCR result in a linear or an exponential increase in the amount of target DNA?
Exponential
47
Approximately how long does PCR take to perform?
A few minutes
48
Name the 2 key innovations that facilitated the routine use of PCR in the laboratory
- Thermostable DNA polymerase
- PCR machines
49
Why was DNA polymerase from E. coli abandoned in favor of a more thermostable DNA polymerase? (2)
- It denatures at 90°C
- Fresh enzyme had to be added in each cycle which slowed the process
50
What is the name of the thermostable DNA polymerase used in most modern PCR applications?
Taq polymerase
51
How do PCR machines (thermal cyclers) work?
Cause temperature changes necessary for the different steps of PCR
52
What does the term electrophoresis literally mean?
To carry with electricity
53
How is electrophoresis used in molecular biology?
Separates molecules based on their size and electrical charge
54
What type of electrophoresis is used to separate DNA molecules?
Gel electrophoresis
55
Describe agarose (2)
- Purified extract of agar isolated from seaweed
- Melted in a buffer solution
56
What is the function of agarose in electrophoresis?
Small pores allow DNA to migrate through
57
To which end of the gel are the DNA samples added?
Negative end
58
Describe the principle by which DNA fragments migrate through an agarose gel during gel electrophoresis
Since the phosphate group of each DNA carries a negative charge, the DNA fragments migrate toward the positive end of the gel
59
What effect does fragment size have upon the migration rate of DNA molecules through an agarose gel during gel electrophoresis?
Small DNA fragments migrate more rapidly than large DNA fragments
60
Comparing migration distance of the unknown fragments with the distance traveled by the size standards determines ...
The approximate size of the unknown fragments
61
How are DNA fragments visualized after gel electrophoresis?
Using a dye specific for nucleic acids
62
Describe the role of ethidium bromide in the visualization of DNA fragments after gel electrophoresis (3)
- Wedges itself between the bases of DNA
- Fluoresces when exposed to UV light
- Produces bands on the gel
63
Describe electroporation as a means of introducing DNA into target cells
An electric current punctures microscopic holes through the cell membrane
64
When inserting DNA into the cells of plants, algae, and fungi, they must first be converted into ______
Protoplasts
65
What are protoplasts?
Cells with cell walls that have been enzymatically removed
66
How are protoplasts used in electroporation? (2)
- Cytoplasmic membranes of protoplasts fuse
- Forms a cell with genomes of both parent cells
67
Describe protoplast fusion as a means of generating recombinant cells
Recombination of DNA from 2 fused cells
68
What role does polyethylene glycol (PEG) play in protoplast fusion?
Increases the rate of fusion
69
What are gene guns?
Compressed helium gas that fires into a target cell
70
What kinds of energy are used to power gene guns?
Tungsten / gold beads coated with DNA
71
Microinjection is the insertion of DNA into target cells using a ______
Glass micropipette
72
Describe heat shock as a means of introducing DNA into target cells
Bacterial cells are shocked into taking up DNA from their environment
73
Define traditional agriculture
Controlled breeding of plants and animals to obtain desired traits
74
Regarding selection, what is traditional agriculture based on?
Phenotype
75
Why does selection in traditional agriculture affect many genes?
It is imprecise
76
DNA-based techniques manipulate ...
Multiple genes at a time
77
Organisms with altered genes / altered expression of their own genes are called ______
GMOs
78
Describe golden rice as an example of a genetically modified crop
Uses genes from corn and bacteria to produce 23x as much β carotene
79
β carotene is a ______
Vitamin A precursor
80
Define bioremediation
Release of bacteria with the ability to detoxify pollutants
81
How is bioremediation a genetic technology?
Organisms metabolize substances that would normally be considered toxins
82
Bioremediation uses ______
Unaltered organisms
83
Bioremediation transfers ______ to other species
Detox genes
84
______ can more easily penetrate a polluted area
Protein products
MICRB 106 - Exam 3
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