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Biology > Section 8- Gene expression > Flashcards

Section 8- Gene expression Flashcards

(59 cards)

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1
Q

What are mis-sense mutations?

A

Incorrect amino acid which may produce a malfunctioning protein

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2
Q

What is a nonsense muation?

A

STOP codon

Truncates protein into something smaller

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3
Q

What is a silent mutation?

A

Not harmful

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4
Q

What is a base duplication?

A

A number of bases are repeated causing a frameshift to the right

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5
Q

What is a base inversion?

A

A number of bases are reveresed

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6
Q

What is translocation mutation?

A

A number of bases are removed from one chromosome and become inserted in a different gene

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7
Q

What is a whole chromosome mutation?

A

Insertion of another chromosome

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8
Q

What are the effects of mutations?

A

Production of new advantageous protein = gain of reproductive advantage

Neutral mutation = no change

Production of disadvantageous protein = fatal or disease causing

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9
Q

What is a stem cell?

A

An undifferentiated cell

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10
Q

What is stem cell diferentiation?

A

Specialising cells

Replaces dead or damaged cells throughout the life of the organsim

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11
Q

What does totipotent mean?

A

A fertilised eff has the potential to form every type of human cell

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12
Q

What does pluripotent mean?

A

Capable of producing all cells derived from a particular germ layer

Restricted number

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13
Q

What is multipotent?

A

Can make a restricted range of related cell types

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14
Q

What is unipotent?

A

Able to make only one cell type

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15
Q

What happens with stem cells in plants?

A

Maintain totipotency in form of meristem cells

Cutting/ tissue culture can be used to produce whole plants or plant organs under the right growth conditions

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16
Q

What percentage of genes are being used at any one time?

A

3-5% of their genes at any given time

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17
Q

What are transcription factors?

A

Proteins which move in from the cytoplasm and bind to DNA at specific sites

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18
Q

What is a promoter region?

A

The specific site on DNA which transcription factor binds to

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19
Q

How do transcription factors activate a gene?

A

Allow RNA polymerase to attach to the DNA chain and start transcription

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20
Q

What is transcription initiated by?

A

RNA polymerase AND transcription factors binding to the DNA

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21
Q

What are transcription factors activated by?

A

Stimulated by hormones or growth factors

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22
Q

How does oestrogen stimulate the expression of a gene?

A

Oestrogen is lipid soluble so diffuses through membrane

It combines with receptor site on the transcription factor (complementary binding)

Causes change of shape to the transcription factor causing it to release the inhibitor molecules

Transcription factor enters the nucleus through a nuclear pore and combines with DNA activating transcription

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23
Q

What are epigenetics?

A

It is the study of heritable changes in gene function that do not involve changes to the base sequence of DNA

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24
Q

What is the epigenome and what it is determined by?

Study These Flashcards
A

It is the combination of chemical tags present on DNA

Determined by environmental factors

25
What do histones allow for?
Allow eukaryotic DNA to coil and condense
26
What happens if DNA is tightly wrapped around histones?
Genes are inaccessible for transcription Epigenetic silencing
27
What happens is DNA is loosely wrapped around histones?
Genes are accessible and easily transcribed
28
What is acetylation?
Adding of acetyl group to histone group Leads to activation of genes causing DNA to uncoil Switches gene on
29
What happen when acetyl groups are removed?
Gene is inactivated DNA coils slightly Gene switched off
30
What is hypo-methylation?
Hypo (low) methylation increases transcription Of cytosine
31
What is hyper-methylation?
Hyper (high) methylation inhibits transcription Of cytosine
32
What can cancer be associated with?
Reduced DNA methylation of proto-oncogenes which oncogenes Increased methylation of promotor regions causing deactivation of tumour suppressor genes
33
What are oncogenes?
Acts to promote tumour growth Mutated proto-oncogenes
34
What are tumour suppressor genes?
Prevents formation of tumour by preventing cell cycle Control cell division by inhibiting the proto-oncogenes, repairing DNA and activating cell death
35
How can diseases be treated with gene expression?
Enzymes involved in acetylation or methylation inhibited
36
How can disease be diagnosed with gene expression?
Relies on detection of levels of methylation and acetylation relative to 'normal' levels
37
What is the effect of siRNA on gene expression?
1. Enzyme cuts double-stranded molecules of RNA into siRNA 2. siRNA combines with enzyme and is broken down in to separate strands 3. siRNA molecule guides enzyme to mRNA molecule by complimentary base pairing 4. Enzyme cuts mRNA into smaller sections mRNA can no longer be translated into polypeptide Gene is not expressed
38
What does siRNA stand for?
Small interfering RNA
39
What are carcinogens and what do they do?
Cancer causing agents Cause changes to genes that control cell division
40
What are benign tumours?
Grow slowly but can get very large Tend to remain as a distinct structure and only affect a specific part of the body Less likely to be life threatening but can disrupt functioning of organs Can be removed by surgery alone
41
What are malignant tumours?
Grow rapidly and can get very large Tend to extend into surrounding tissues Develop own blood and lymph systems May spread to other areas of the body by metastasis Treatment may involve radiotherapy and chemotherapy as well as surgery
42
What are proto-oncogenes and what do they control?
Stimulate cells division and control rate of cell division A specific proto-oncogene needs to be switched on by a growth factor or hormone to cause cell to grow and divide
43
What can a proto-oncogene mutate into and what is the result?
Can mutate into an oncogene Results in gene activation in the absence of a growth factor One copy of a mutated proto-oncogene is enough to stimulate cells to divide out of control
44
What can a tumour suppressor gene mutate into?
Can become inactivated Allows rate of cell division to increase or DNA not to be replicated Both copies of the gene need to be mutated to cause cancer
45
What are induced pluripotent stem cells?
Type of pluripotent cell that is produced from unipotent stem cells Body cells are genetically altered in a lab to make them have characteristics of embryonic stem cells No need for embryos All possible type of specialised cells
46
What is the human genome project?
Aim: To identify all genes in human DNA Find where each gene is located Determine sequence of bases
47
What was the estimated cost and time of the human genome project?
Time = 15 years - took 13 years Cost = $3 billion
48
What is whole-genome shotgun sequencing?
When researchers cut DNA into small easily sequenced sections and use a computer algorithm to align overlapping segments
49
What is whole-genome shotgun sequencing and how is it used to sequence DNA?
Involves researchers cutting the DNA into many small, easily sequenced sections Then using computer algorithms to align overlapping segments to assemble entire genome
50
What are single nucleotide polymorphisms (SNPs)?
Single-base variations in the genome that are associated with disease and other disorders
51
Why is it easy to determine the proteome of prokaryotes?
No introns Only one circular piece of DNA, not associated with histones
52
How can the methylation of tumour suppressor genes lead to cancer?
No transcription due to methylation No control of mitosis Protein produced prevents cell division
53
What is methylation?
Attracting enzymes that can add or remove methyl groups to cytosine
54
What is the DNA-histone complex?
Where the association of histones with DNA is weak, the DNA-histone complex is less condensed DNA is accessible by transcriptional factors Can initiate production of mRNA, switch on the gene
55
How can hypomethylation cause cancer?
Reduced methylation Occurs in oncogenes, leading to their activation
56
How can increased oestrogen in menopausal women cause cancer?
Release inhibitor molecule that prevents transcription causing proto-oncogenes to develop into oncogenes Oncogenes increase rate of cell division leading to development of a tumour
57
What is the process of genome sequencing?
Extract samples of DNA from cells Cut DNA into sections of varying lengths Amplify DNA Sequence short sections of DNA Place sections in order by matching overlapping regions
58
Why would siRNA only affect gene expression in cells infected with HIV?
Only infected cells contain mRNA
59
What are 2 ways in which the structure of siRNA differs from mRNA?
siRNA is double stranded siRNA is smaller

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