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Biology- Topic 8 > control of gene expression > Flashcards

control of gene expression Flashcards

1
Q

gene mutation

A

change in base sequence of DNA
- occurs during DNA replication
- includes addition, deletion, substitution, inversion, duplication and translocation of bases

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2
Q

mutagenic agents

A

chemical or radiation that
increases mutation rate

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3
Q

addition mutation

A

One extra base is added to the DNA sequence
causes all subsequent codons to be altered (frameshift)

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4
Q

deletion mutation

A

One base is deleted in the DNA sequence.
causes all subsequent codons to be altered (frameshift)

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4
Q

translocation of bases mutation

A

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

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5
Q

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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6
Q

frameshift

A

A change in all the codons after the point of mutation
each base shifts left or right one position

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7
Q

non-functioning protein

A

a protein with a different primary and tertiary structure therefore the shape is changed
- it cannot carry out its function

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7
Q

duplication mutation

A

One base is duplicated at least once in the sequence
- causes a frameshift to the right

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7
Q

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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8
Q

benign tumour

A
  • non-cancerous tumour
  • grows large but at a slow rate
  • produce adhesive and are surrounded by a capsule so they cannot spread
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8
Q

tumour

A

a mass of cells as a result of uncontrolled cell division
- can be benign or malignant

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9
Q

malignant tumour

A
  • cancerous tumour
  • grows rapidly
  • can become unspecialised can metastasise
  • grow projections
  • develop own blood supply
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10
Q

cancer

A

Malignant tumours that form due to uncontrolled cell division

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10
Q

metastasis

A

cancer cells breaking off from the tumour
- spreading to form secondary tumours in different tissues or organs

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11
Q

oncogene

A
  • a mutated version of a proto- oncogene
  • results in constant initiation of DNA replication and mitotic cell division
  • causes tumour formation
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12
Q

How can oestrogen increase the risk of breast cancer?

A
  • Oestrogen is a steroid hormone 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
  • can result in uncontrolled cell division
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12
Q

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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12
Q

methylation of DNA

A
  • inhibits transcription
  • methyl groups attach to the cytosine base on DNA
  • prevents transcriptional factors from binding
  • condenses the DNA-histone complex
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13
Q

epigenetics

A
  • the heritable change in gene function without changing the DNA base sequence
  • caused by changes in the environment
  • can inhibit transcription
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14
Q

hypermethylation

A
  • an increased number of methyl groups attached to a gene - results in the gene being deactivated
  • results in cancer if happens to a tumour suppressor gene
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14
Q

Stem cell

A

undifferentiated cells that can continually divide and become specialised

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15
Q

Pluripotent stem cell

A

can differentiate into almost any body cell
occur in embryos

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16
Q

Multipotent stem cell

A

can differentiate into a limited number of cells
found in mature mammals e.g in bone marrow

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17
Totipotent stem cell
can differentiate into any body cell occur for a limited time in early mammalian embryos
18
Unipotent stem cell
can differentiate into one type of cell found in mature mammals
19
Induced pluripotent stem cell
produced from adult somatic cells - using protein transcriptional factors - overcomes ethical issues of using embryonic stem cells
20
Transcriptional factor
proteins that can bind to different base sequences on DNA - initiate transcription of genes
21
What is a vector?
a DNA molecule used as a vehicle to carry a DNA fragment e.g. plasmids/viruses
22
Acetylation of histones
- Decreased acetylation inhibits transcription - removing acetyl groups makes the histones more positive - this attracts the negative phosphate group on DNA - making it harder for the transcriptional factors to bind
23
siRNA
small interfering RNA destroys mRNA molecules to prevent translation
24
How can you create a DNA fragment?
* Reverse transcription with reverse transcriptase * restriction endonucleases * gene machine
24
RNA interference
inhibition of the translation of mRNA the mRNA gets destroyed so it cannot be translated
25
Recombinant DNA technology
combining different organisms’ DNA enable scientists to manipulate and alter genes to improve industrial processes and medical treatment
26
Sequencing projects
Reading the full genome of organisms provides opportunities to screen DNA to identify potential medical problems
27
Reverse transcriptase
An enzyme that makes cDNA single-stranded copies of DNA from mRNA
27
Gene machine
creates DNA fragments using a computerised machine
28
Restriction endonulceases
- Enzymes that cut up DNA to create fragments - cut at specific recognition/restriction sequences - results in sticky ends
29
In vivo cloning
Creating DNA fragments using bacteria involves restriction endonulcease enzymes
30
In vitro cloning
Using PCR to create a large number of copies of a DNA fragment
31
Uses of PCR
Used widely in gene technology to make large numbers of copies of DNA fragments e.g. forensics, genotyping, cloning, paternity tests, microarrays
32
Describe the PCR process
- increase temperature to 95C to break hydrogen bonds & split DNA into single strands - temperature is decreased to 55C so primers can attach - DNA polymerase joins complementary nucleotides & makes a new strand - temperature increased to 72C (optimum for Taq DNA polymerase)
33
Uses of genetic fingerprinting
Forensic science medical diagnosis plant/animal breeding paternity tests
34
What is gel electrophoresis
Separation of DNA samples using an electrical voltage - different lengths of DNA VNTRs are separated
35
Why does the 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
36
What is genetic screening?
Testing DNA to identify the presence of alleles that can cause/increase the risk of developing a disease
37
What is genetic counselling?
a type of social work giving people advice and information following the screening of disease causing alleles
38
What is cDNA?
Complementary, single- stranded DNA strands created by reverse transcriptase
39
What are the advantages of using the gene machine?
Very quick accurate create intron-free DNA
40
Oligonucleotides
Short DNA molecules used in gene machines to create DNA fragments
40
What are the advantages of using restriction endonculeases?
Creates sticky ends on DNA to enable the DNA fragments to join with complementary base pairs
40
What are the advantages of using reverse transcription?
Creates intron-free cDNA
41
Sticky ends
Exposed staggered ends of bases palindromic base sequences created by restriction endonuclease enzymes
42
Palindromic sequence
sequences of bases that read the same forwards as they do backwards
43
What are the two methods to amplify DNA?
In vivo in vitro (PCR)
44
Promoter region
a sequence of DNA that is the binding site for RNA polymerase to enable transcription to occur
44
Blunt end
When a restriction endonuclease cuts the DNA double-strand in the same position - there is no overhang of bases
45
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
46
Plasmid
a small loop of bacterial DNA - contains only a few genes - contains the genes for antibiotic resistance
47
Recombinant plasmid
a small loop of bacterial DNA with the DNA from another organism inserted into it
48
Transformation
the process of getting a plasmid to re-enter a bacterium - involves calcium ions and temperature shocking
49
How can transformed cells be identified?
- using marker genes - antibiotic resistance genes - genes coding for fluorescent proteins - genes coding for enzymes
50
# ** What is a marker gene?
genes on the plasmid used to identify which bacteria successfully took up the recombinant plasmid
51
DNA probe
short, single-stranded pieces of DNA - labelled radioactively or fluorescently so that they can be identified
52
DNA hybridisation
- DNA is heated to separate the double helix into single strands - it is then mixed with complementary sequences of single-stranded DNA - it is then cooled so complementary strands will anneal
53
Personalised medicine
screening for the presence of particular alleles to select medicines and personalise health advice based on your genotype
54
VNTRs
variable number tandem repeats sequences of bases in introns unique to each person
55
How can DNA samples be collected?
From blood, body cells or hair follicles
56
How is DNA extracted from cells so that it can be examined?
cell fractionation and ultracentrifugation
57
How is DNA digested in genetic fingerprinting?
- Restriction endonucleases are added to cut the DNA into smaller fragments - enzymes that cut close to the target VNTRs are added
57
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
58
What is the role of DNA ligase in making recombinant DNA?
used to stick the DNA fragment to create recombinant DNA

Biology- Topic 8 (1 decks)

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