Biology > Topic 8A: Mutations and Gene Expression > Flashcards

Topic 8A: Mutations and Gene Expression Flashcards

(48 cards)

Study These Flashcards
1
Q

What are benign tumours?

A
  • Not cancerous
  • Grow more slowly
  • Harmless but can put pressure on organs and impact function
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are malignant tumours?

A
  • Cancerous
  • Grow rapidly
  • Invade other tissues
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is a mutation?

A
  • Any change in base sequence of DNA
  • Can change the primary structure of amino acids
  • Position of H bonds can change in secondary and tertiary structures
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are frameshift mutations?

A
  • Causes all bases after the point of mutation to change
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is a substitution?

A
  • One nucleotide replaced by another with a different base
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is an addition?

A
  • Extra nucleotide added -> adds extra base to the sequence
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is a deletion?

A
  • One nucleotide removed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is a duplication?

A
  • One or more bases repeated
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is an inversion?

A
  • A sequence of bases reversed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is a translocation?

A
  • Sequence of bases moved either within the same chromosome or to a different chromosome
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Which mutations do not cause a frameshift?

A
  • Substitution
  • Inversion
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What 3 ways can mutagenic agents act?

A

1 - Act as a base -> chemical called base analogs can substitute for a base during DNA replication changing base sequence
2 - Altering bases -> some chemicals can delete / alter bases
3 - Changing structure of DNA -> some types of radiation can do this causing problems during DNA replication

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How do tumour suppressor genes usually act?

A
  • Produce proteins that stop cells dividing, cause apoptosis or anchor cells in place
  • Slow cell division
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What happens when tumour suppressor genes mutate?

A
  • Protein not produced
  • Cells divide uncontrollably causing a tumour
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How do proto-oncogenes usually act?

A
  • Code for proteins that stimulate cell division
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What happens when proto-oncogenes mutate?

A
  • Form oncogenes
  • Overactive so cause uncontrolled cell division
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are features of tumour cells?

A
  • Irregular shape
  • Larger and darker nucleus
  • Different antigens
  • Divide more rapidly
  • Don’t produce all needed proteins
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What happens when tumour suppressor genes hypermethylated?

A
  • Not transcribed
  • Proteins not made
  • Increase cell division
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What happens when proto-oncogenes hypomethylated?

A
  • Act as oncogenes
  • Increase in protein production
  • Increased division
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What 3 ways can oestrogen increase the risk of breast cancer?

Study These Flashcards
A

1 - Can stimulate breast cells to divide and replicate - increases chances of mutations
2 - If cells become cancerous - divide faster than usual
3 - Able to introduce mutations directly into DNA of certain breast cells

21
Q

What genes are permanently expressed?

Study These Flashcards
A
  • Those that code for respiratory enzymes
22
Q

What are stem cells?

Study These Flashcards
A
  • Undifferentiated cells that can specialise into other cell types
  • Can self renew and differentiate
23
Q

How does differentiation occur?

Study These Flashcards
A
  • All cells have same genes - not all expressed
  • In correct conditions some genes expressed - mRNA transcribed from specific genes
  • Translated into proteins which modify the cell structure and processes
  • Changes make the cell specialised
24
Q

What are totipotent stem cells?

Study These Flashcards
A
  • Form any body cell
25
What are pluripotent stem cells?
- Can become any embryonic cells - not placenta
26
What are multipotent stem cells?
- Can differentiate into a few cell types
27
What are unipotent stem cells?
- Can only produce one type of cell
28
What are cardiomyocytes?
- Heart muscle cells made from a unipotent stem cell - Heart has regenerative capacity
29
How are adult stem cells used and features?
- From bone marrow etc - Little risk to remove - Less flexible - only multipotent - Can use own stem cells - less risk of rejection
30
How are embryonic stem cells used and features?
- Produced by IVF - After 4-5 days remove stem cells - Rest destroyed - More useful - pluripotent
31
What are iPS cells and how are they produced?
- Reprogram adult stem cells to be pluripotent - made to express transcription factors associated with pluripotency - Factors introduced by modified virus - has genes for transcription factors
32
What are ethics about embryonic stem cells?
- Destroys potential foetus - wrong to destroy something that has the 'right to live' - Fewer objections to unfertilised eggs that are artificially activated to divide - Some think they should only use adult stem cells - but much less fluid
33
Describe totipotency in plant cells?
- Many plant cells can develop into other cells - Can be grown in a test tube - cuttings - can form clones of genetically identical plants - Plants have higher totipotency than animals
34
What is a plant callus?
- Mass of unorganised and undifferentiated plant cells cultured on agar gel medium
35
What is transcription controlled by?
- Transcription factors
36
How do activator transcription factors work?
- Binds to promotor region of the gene to be transcribed - Help RNA polymerase bind in position (at start of gene) - Gene transcribed, mRNA produced, protein made
37
How do repressor transcription factors work?
- Binds to promotor region of DNA - prevents RNA polymerase binding - Gene not transcribed, no mRNA, no protein made
38
How does oestrogen affect transcription?
- Lipid soluble - diffuses through phospholipid bilayer - Complimentary shape to receptor on transcription factor - Forms oestrogen - oestrogen receptor complex - alters DNA binding site on transcription factor - Factor now enters nucleus - binds to promotor region of DNA, activates transcription positioning RNA polymerase at the start of the gene
39
How does siRNA work?
- mRNA leaves nucleus to cytoplasm - Double stranded siRNA associates with several proteins, unwinds - single strand binds to target mRNA - Base sequence complimentary to target mRNA - Associated proteins cut mRNA into fragments so it cannot be translated - Fragments move to processing body which degrades them - Similar process with miRNA in plants
40
In what organisms does miRNA work?
- mammals
41
How does miRNA work?
- Not fully complimentary to target mRNA - Less specific so may target more than one mRNA molecule - Associates with proteins and binds to target mRNA in cytoplasm - miRNA-protein complex physically blocks translation of target mRNA - mRNA moved to processing body - either stored or degraded - When stored - can be returned and translated another time
42
Define epigentics
- Heritable changes in gene function without changes to the base sequence of DNA
43
What is epigenetic control?
- Determines whether a gene is expressed - Attachment or removal of chemical groups (epigenetic marks) to or from DNA or histone proteins - Don't alter base sequence, alter ease of transcription
44
How can epigenetics be inherited?
- Most epigenetic marks on DNA removed between generations - some escape and passed on - Expression of some genes in offspring can be affected by environmental changes that affected their parents etc
45
What is a methyl and what does it attach to?
- CH3 - DNA
46
How does methylation work?
- Attaches to CpG site - where cytosine and guanine next to each other on a strand - Increased methylation changes DNA structure so that transcriptional machinery (RNA polymerase etc) cannot bind - No transcription - gene not expressed - protein not produced
47
What is an acetyl group and where does it attach?
- COCH3 - Histones
48
How does acetylation work?
- When acetylated - chromatin less condensed - Enzymes and transcription factors can access DNA allowing transcription - Less acetylated - more condensed - less transcription - Histone deacetylase (HDAC) enzymes remove acetyl groups
Biology
flashcards
Decks in class (22)
# Cards
Brainscape helps you reach your goals faster, through stronger study habits.
© 2026 Bold Learning Solutions. Terms and Conditions