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Control of Gene Expression Flashcards

1
Q

What are the causes of mutation?

A

Mutagenic chemicals
Spontaneous mutation
Radioactive materials

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2
Q

Insertion / deletion

A

one or more nucleotide pairs are inserted or deleted from the sequence, altering the sequence of nucleotides causing a frameshift

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3
Q

Duplication

A

one or more bases are repeated, causing a frameshift

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4
Q

Inversion

A

A group of bases is seperated from DNA and rejoin at the same position but in reverse order

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5
Q

Translocation

A

A group of DNA base become seperated from the sequnce and are inserted into the DNA sequence of another chromosome.

Significant effects on the phenotype

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6
Q

Totipotent stem cells

A

Can differentiate into any cell type

Found in zygotes

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7
Q

Pluripotent stem cells

A

Form almost any cell type

Early stages of embryo

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8
Q

Multipotent stem cells

A

Can differentiate into limited cell types

Found in bone marrow and umbilical cord

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9
Q

Unipotent stem cells

A

Can only differentiate into one cell type

Germ line stem cells
Epidermal stem cells

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10
Q

What are pluripotent stem cells useful for?

A

repairing damaged tissue

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11
Q

Why is the genetic code degenerate?

A

there are multiple tRNA molecules for each amino acid

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12
Q

Where are transcription factors produced?

A

Cytoplasm

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13
Q

How do repressors prevent the transcription of genes?

A

They stop RNA polymerase from binding to DNA

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14
Q

Which 2 types of hormones are involved in the regulation of transcription?

A

Peptide Hormones

Lipid-soluble Steroid Hormones

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15
Q

What is the benefit of oestrogen being lipid-soluble?

A

It can pass through the phospholipid bilayer

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16
Q

What does the receptor-hormone complex bind to in order to activate transcription?

A

Promotor region of DNA

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17
Q

What is the effect of Methylation on transcription?

A

Methylation inhibits transcription

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18
Q

What is the role of tumour suppressor genes?

A

Inhibit cell division

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19
Q

What type of RNAi is complementary to the mRNA sequence

A

siRNA

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20
Q

What charge do histone proteins have?

A

Positive

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21
Q

What charge does DNA have?

A

Negative

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22
Q

What are the 2 techniques used to diagnose disease using DNA probes?

A

Electrophoresis

Microarray

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23
Q

What does electrophoresis do?

A

Seperates DNA fragments according to size

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24
Q

What is a microarray?

A

it is a plate with many indents with DNA probes for a specific gene in each indent

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25
What labels are used on DNA probes to diagnose disease?
Radioactive phosphate tag Fluorescent tag
26
How are patients advised about genetic screening?
Genetic Counselling
27
2 types of gene therapy
Germline Therapy Somatic Therapy
28
At what end of the gel is DNA inserted in gel electrophoresis?
The negative end
29
Totipotent stem cells in development
Translate only part of their DNA, meaning the cells remain unspecialised
30
Example of unipotent stem cells
Cardiomyocytes produce new muscle cells
31
When do totipotent stem cells become specialised?
During embryonic development When the cells become specialised, onlu some genes are activated and only the activated genes are expressed
32
Proteins in differentiation
If a gene is expressed, it is transcribed into mRNA and translated into a protein Differentiation happens as certain proteins are made The presence of certain proteins means a cell has become specialised
33
Sources of stem cells
Adult stem cells Embryonic stem cells Induced Pluripotent stem cells
34
Uses of stem cells in disease
Grow organs for organ transplants Replace damaged cells in the spinal cord causing paralysis
35
How are IPS produced?
Somatic cells converted to iPS by activating genes using appropriate protein transcription factors This makes somatic cells become unspecialised so they can be used to treat disease
36
Bone Marrow Transplants
Used to treat blood and immune disorders Contain multipotent stem cells that can produce all types of blood cell
37
Stem cells in drug research
Used to grow artificial tissue Drugs can be tested on these artificial tissues before being tested on humans
38
Stem cells in developmental biology
Learn about how an embryo develops and how organs are formed Improve medicines by learning about why organs have abnormalities
39
Stem cells - potential future research
Produce new organs or tissues for transplants Treat irreversible diseases, such as diabetes or paralysis
40
Transcription Factors
Proteins that control gene expression by stimulating or inhibiting the transcription of target genes In the nucleus, transcription factors bind to a specific region of DNA to stimulate or inhibit the gene
41
Activators
Transcription Factors that stimulate gene expression Promote the transcription of genes by interacting with RNA polymerase and allowing it to bind to DNA
42
Repressors
Transcription factors that inhibit gene expression Prevent the transcription of genes by stopping RNA polymerase from binding to DNA
43
Peptide Hormones
Bind to the cell surface membrane and trigger a secondary messenger response The secondary messenger will lead to the activation or inhibition of transcription of some genes
44
Lipid-soluble steroid hormones
Pass through the phospholipid bilayer Steroid hormones interact directly with DNA to promote or inhibit gene expression
45
Why can oestrogen pass through the phospholipid bilayer?
It is lipid-soluble
46
How does Oestrogen enter the nucleus
Binds to receptors on transcription factors in the cytoplasm, causing the transcription factors to change shape Receptor-hormone complex formed which can now enter the nucleus
47
Oestrogen Stimulates protein synthesis
Receptor-hormone complex binds to the promotor region of DNA Binding to DNA activates transcription
48
Chromatin
The combination of proteins and histones
49
Epigenome
The chemical layer surrounding chromatin
50
Effect of the epigenome on chromatin
Chromatin becomes more condensed, preventing TFs from binding to DNA transcription is inhibited Chromatin becomes less condensed, allowing easier access to TFs, promoting transcription
51
Epigenetic Markers
Do not alter the base sequence, but alter chromatin structure
52
What do methyl groups bind to?
CpG sites on DNA - Where cytosine and guanine are together in the base sequence
53
Effect of methyl groups on chromatin
Chromatin becomes more condensed, meaning Tfs can't reach DNA and transcription is inhibited
54
Decreased Acetylation
Acetyl groups are removed from histone proteins, which increases the positive charge on histone proteins, increasing the attraction to the phosphate groups on DNA Causes chromtin to condense, so RFs can't reach DNA
55
Effect of Increased Methylation
Decrease the expression of tumour suppressor genes more than normal Cells divide uncontrollably and tumours are produced
56
Effect of decreased methylation
Increase gene expression of proto-oncogenes more than normal Cells divide uncontrollably and tumours are produced
57
What can translation be inhibited by?
RNAi
58
Translation
synthesising proteins using the genetic code After transcription, mRNA moves from the nucleus to the cytoplasm Translation reads the sequence of bases on mRNA and joins corresponding amino acids together to produce a protein
59
RNAi
Small molecule of double-stranded RNA Interfered with mRNA by binding to the mRNA moolecule and breaking it down, preventing it from being translated
60
siRNA
A type of RNAi that is complementary to the mRNA sequence it inhibits Targets a specific sequence of mRNA, breaking it down to smaller fragments upon binding The fragments of mRNA are degraded
61
miRNA
Not fully complementary to the mRNA sequence Target multiple sequences of mRNA After miRNA has bound to mRNA, the mRNA is either degraded or stored for future
62
Oncogenes
Mutations in a proto-oncogene Capable of transforming a cell into a cancerous cell because they cause excessive cell division Normally stimulate cell divison Decreased methylation of a proto-oncogene causes proto-oncogenes to be overexpressed, stimulating cell division
63
Drug used to treat HER2 mutation
Herceptin
64
DNA Fragments
The sections of DNA that are transferred to make recombinant DNA
65
Recombinant DNA
The process of transferring sections of DNA from one organism to another
66
Transgenic
The name given to the organism that has recieved fragments of DNA
67
Universal code
The name given to DNA due to the fact every organism uses the same 4 bases to produce proteins
68
3 ways of producing DNA fragments
Reverse transcriptase restriction Endonuclease Gene machine
69
Reverse Transcriptase
Coverts single-stranded mRNA into double-stranded DNA Producing DNA fragments Produces cDNA
70
Recognition Sequences
Sections of DNA where the base sequence has palindromic base pairs Used to isolate the target gene if there are 2 sets of sequences either side of the gene
71
How can a target gene be cut out of a recognition sequence?
Binding of 2 restriction endonuclease
72
How can DNA fragments be produced in a gene machine?
Synthesising the target gene sequence using free-floating nucleotides
73
Usefulness of a gene machine
DNA template isn't necessary Sequence for target gene is obtained from a database
74
Producing Fragment in gene machine
sequence for the target gene is obtained from a database Nucleotides added in correct order to synthesise correct base sequence Protecting groups added throughout to ensure correct nucleotides are added and no side branches are produced
75
Why are Sticky ends on DNA fragments complementary to sticky ends on vector DNA?
Cut using the same restriction endonuclease Seversal nucleotides have been added onto the end of the fragment
76
DNA ligase
Attaches sticky ends together
77
Vector - Plasmid
The host cell takes up the recombinant DNA via heat-shock, this is where the cells are heated to 42'C for one minute
78
Vector - Bacteriophage
Recombinant DNA is injected into host cells
79
How are transformed cells identified?
Marker genes

Biology (7 decks)

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