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Biology Paper 2 > Control Of Gene Expression > Flashcards

Control Of Gene Expression Flashcards

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1
Q

What is a gene mutation?

A

A change in the base sequence of DNA.

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2
Q

When does a gene mutation occur?

A

During DNA replication.

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3
Q

What types of changes can occur in a gene mutation?

A

Addition, deletion, substitution, inversion, duplication, and translocation of bases.

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4
Q

What are mutagenic agents?

A

Chemicals or radiation that increase the mutation rate.

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5
Q

What is an addition mutation?

A

One extra base is added to the DNA sequence.

This causes all subsequent codons to be altered (frameshift).

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6
Q

What is a deletion mutation?

A

One base is deleted in the DNA sequence.

This causes all subsequent codons to be altered (frameshift).

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7
Q

What is a substitution mutation?

A

One base in the DNA sequence is changed.

No frameshift; only one codon changes; may have no impact due to degenerate genetic code.

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8
Q

What is a frameshift mutation?

A

A change in all the codons after the point of mutation.

Each base shifts left or right one position.

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9
Q

What is an inversion mutation?

A

A section of bases detach from the DNA sequence and re-join inverted.

Results in different amino acids being coded for in this region.

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10
Q

What is a duplication mutation?

A

One base is duplicated at least once in the sequence.

Causes a frameshift to the right.

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11
Q

What is translocation of bases mutation?

A

A section of bases on one chromosome detaches and attaches to a different chromosome.

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12
Q

What is a non-functioning protein?

A

A protein with a different primary and tertiary structure; therefore, the shape is changed and it cannot carry out its function.

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13
Q

What is a tumour?

A

A mass of cells as a result of uncontrolled cell division; can be benign or malignant.

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14
Q

What is a benign tumour?

A

A non-cancerous tumour that grows large but at a slow rate; produces adhesive and is surrounded by a capsule so it cannot spread.

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15
Q

What is a malignant tumour?

A

A cancerous tumour that grows rapidly, can become unspecialised, can metastasise, grow projections, and develop its own blood supply.

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16
Q

What is cancer?

A

Malignant tumours that form due to uncontrolled cell division.

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17
Q

What is metastasis?

A

Cancer cells breaking off from the tumour and spreading to form secondary tumours in different tissues or organs.

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18
Q

What is an oncogene?

A

A mutated version of a proto-oncogene that results in constant initiation of DNA replication and mitotic cell division, causing tumour formation.

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19
Q

What are tumour suppressor genes?

A

Genes that produce proteins to slow down cell division and cause cell death if DNA copying errors are detected.

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20
Q

What is epigenetics?

A

The heritable change in gene function without changing the DNA base sequence, caused by changes in the environment, and can inhibit transcription.

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21
Q

What is hypermethylation?

A

An increased number of methyl groups attached to a gene, resulting in the gene being deactivated, which can lead to cancer if it occurs in a tumour suppressor gene.

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22
Q

What is methylation of DNA?

A

Inhibits transcription by attaching methyl groups to the cytosine base on DNA, preventing transcriptional factors from binding and condensing the DNA-histone complex.

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23
Q

What is oestrogen?

A

Oestrogen is a steroid hormone.

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24
Q

How does oestrogen increase the risk of breast cancer?

A

It binds to a receptor site on a transcriptional factor, causing a change in shape so it can bind to the DNA to initiate transcription.

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25
What can result from oestrogen's action?
It can result in uncontrolled cell division.
26
What are stem cells?
Undifferentiated cells that can continually divide and become specialised.
27
What is a totipotent stem cell?
A stem cell that can differentiate into any body cell and occurs for a limited time in early mammalian embryos.
28
What is a pluripotent stem cell?
A stem cell that can differentiate into almost any body cell and occurs in embryos.
29
What is a multipotent stem cell?
A multipotent stem cell can differentiate into a limited number of cells and is found in mature mammals, e.g., in bone marrow.
30
What is a unipotent stem cell?
A unipotent stem cell can differentiate into one type of cell and is found in mature mammals.
31
What is an induced pluripotent stem cell?
An induced pluripotent stem cell is produced from adult somatic cells using protein transcriptional factors.
32
What are the advantages of induced pluripotent stem cells?
Induced pluripotent stem cells overcome ethical issues of using embryonic stem cells.
33
What are transcriptional factors?
Transcriptional factors are proteins that can bind to different base sequences on DNA and initiate transcription of genes.
34
What is a DNA binding site?
A DNA binding site is a region on DNA where transcriptional factors can attach.
35
What is a vector?
A DNA molecule used as a vehicle to carry a DNA fragment. ## Footnote e.g. plasmids/viruses
36
What effect does decreased acetylation have on transcription?
Decreased acetylation inhibits transcription.
37
How does removing acetyl groups affect histones?
It makes the histones more positive, attracting the negative phosphate group on DNA.
38
What is RNA interference?
Inhibition of the translation of mRNA.
39
What happens to mRNA during RNA interference?
The mRNA gets destroyed so it cannot be translated.
40
What is SiRNA?
Small interfering RNA that destroys mRNA molecules to prevent translation.
41
What is recombinant DNA technology?
Combining different organisms' DNA to enable scientists to manipulate and alter genes to improve industrial processes and medical treatment.
42
What are sequencing projects?
Reading the full genome of organisms, providing opportunities to screen DNA to identify potential medical problems.
43
How can you create a DNA fragment?
Using reverse transcription with reverse transcriptase, restriction endonucleases, or a gene machine.
44
What is a gene machine?
A computerized machine that creates DNA fragments.
45
What is reverse transcriptase?
An enzyme that makes cDNA single-stranded copies of DNA from mRNA.
46
What are restriction endonucleases?
Enzymes that cut up DNA to create fragments at specific recognition/restriction sequences, resulting in sticky ends.
47
What is involved in creating DNA fragments using bacteria?
Restriction endonuclease enzymes.
48
What is in vivo cloning?
Creating DNA fragments using bacteria.
49
What is in vitro cloning?
Using PCR to create a large number of copies of a DNA fragment.
50
What are the uses of PCR?
PCR is used widely in gene technology to make large numbers of copies of DNA fragments. ## Footnote Examples include forensics, genotyping, cloning, paternity tests, and microarrays.
51
Describe the PCR process.
1. Increase temperature to 95°C to break hydrogen bonds and split DNA into single strands. 2. Decrease temperature to 55°C for primers to attach. 3. DNA polymerase joins complementary nucleotides to make a new strand. 4. Increase temperature to 72°C (optimum for Taq DNA polymerase).
52
What are the uses of genetic fingerprinting?
Genetic fingerprinting is used in forensic science, medical diagnosis, plant/animal breeding, and paternity tests.
53
What is gel electrophoresis?
Gel electrophoresis is the separation of DNA samples using an electrical voltage, where different lengths of DNA VNTRs are separated.
54
Why does DNA move in gel electrophoresis?
DNA is negatively charged and moves towards the positive end of the gel. The shorter the piece of DNA, the faster and further it moves.
55
What is genetic screening?
Testing DNA to identify the presence of alleles that can cause/increase the risk of developing a disease.
56
What is genetic counselling?
A type of social work giving people advice and information following the screening of disease causing alleles.
57
What is cDNA?
Complementary, single-stranded DNA strands created by reverse transcriptase.
58
What are the advantages of using the gene machine?
Very quick, accurate, create intron-free DNA
59
What are the advantages of using reverse transcription?
Creates intron-free cDNA
60
What are the advantages of using restriction endonucleases?
Creates sticky ends on DNA to enable the DNA fragments to join with complementary base pairs
61
What are oligonucleotides?
Short DNA molecules used in gene machines to create DNA fragments
62
What are sticky ends?
Exposed staggered ends of bases created by restriction endonuclease enzymes. ## Footnote Palindromic base sequences read the same forwards as they do backwards.
63
What is a palindromic sequence?
A sequence of bases that reads the same forwards as it does backwards.
64
What is a blunt end?
When a restriction endonuclease cuts the DNA double-strand in the same position, resulting in no overhang of bases.
65
What are the two methods to amplify DNA?
In vivo and in vitro (PCR).
66
What is a promoter region?
A sequence of DNA that is the binding site for RNA polymerase to enable transcription to occur.
67
What is a terminator region?
Added at the end of the gene, it causes RNA polymerase to detach and stop transcription to ensure one gene is copied into mRNA at a time.
68
What is a plasmid?
A small loop of bacterial DNA that contains only a few genes, including those for antibiotic resistance.
69
What is a recombinant plasmid?
A small loop of bacterial DNA with the DNA from another organism inserted into it.
70
What is transformation?
The process of getting a plasmid to re-enter a bacterium. ## Footnote Involves calcium ions and temperature shocking.
71
What are recombinant plasmids?
Plasmids that have been modified to contain DNA from another source.
72
How can transformed cells be identified?
Using marker genes, antibiotic resistance genes, genes coding for fluorescent proteins, or genes coding for enzymes.
73
What is a marker gene?
Genes on the plasmid used to identify which bacteria successfully took up the recombinant plasmid.
74
What is a DNA probe?
Short, single-stranded pieces of DNA labelled radioactively or fluorescently so that they can be identified.
75
What is DNA hybridisation?
DNA hybridisation is the process where DNA is heated to separate the double helix into single strands, mixed with complementary sequences of single-stranded DNA, and then cooled so complementary strands will anneal.
76
What is the purpose of screening for the presence of particular alleles?
The purpose is to select medicines and personalise health advice based on your genotype.
77
What are VNTRs?
VNTRs (Variable Number Tandem Repeats) are sequences of bases in introns that are unique to each person.
78
How can DNA samples be collected?
DNA samples can be collected from blood, body cells, or hair follicles.
79
How is DNA extracted from cells so that it can be examined?
Cell fractionation and ultracentrifugation.
80
How is DNA digested in genetic fingerprinting?
Restriction endonucleases are added to cut the DNA into smaller fragments. ## Footnote Enzymes that cut close to the target VNTRs are added.
81
Why can the genome not be easily translated into the proteome in complex organisms?
Due to the presence of non-coding DNA and regulatory genes.
82
What is the role of DNA ligase in making recombinant DNA?
Used to stick the DNA fragment to create recombinant DNA.

Biology Paper 2 (4 decks)

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