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A Level Biology > Mutations and Gene Expression (Topic 8A) > Flashcards

Mutations and Gene Expression (Topic 8A) Flashcards

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1
Q

a mutation is…

A

any change to the base nuleotide sequence of DNA

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2
Q

substitution is when…

A

one or more bases are swapped for another

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3
Q

deletion is when…

A

one or more bases are removed

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4
Q

addition is when…

A

one or more bases are added

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5
Q

duplication is when…

A

one or more bases are deleted

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6
Q

inversion is when…

A

a sequence of bases is reversed

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7
Q

translocation is when..

A

a series of bases is moved from one location in the genome to another

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8
Q

some mutations can cause genetic mutations…

A

genetic mutations

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9
Q

why don’t all mutations affect the order of amino acids?

A

the genetic code is degenerate

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10
Q

mutagenic agents are…

A

things that increase the rate of mutations

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11
Q

what ways do mutagenic agents increase the rate of mutations?

A
  1. acting as a base
  2. altering bases
  3. changes the structure of DNA
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12
Q

what two types of gene control cell division?

A

tumor supressor genes
proto-oncogenes

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13
Q

when functioning normally what do tumor supressor genes do?

A

slow cell division by producing protiens that stop cells dividing or cause them to self destruct

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14
Q

when functioning normally what do proto-oncogenes do?

A

stimulate cell division by producing proteins that make cells divide

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15
Q

a mutated proto-oncogene is called an….

A

oncogene

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16
Q

malignant tumors are…

A

cancers

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17
Q

bengin tumors are not….

A

cancerous

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18
Q

how do malignant tumors spread to other parts of the body?

A

cells break off the tumors and spread to other parts of the body in the bloodstream

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19
Q

how do tumor cells differ from normal cells?

A
  • nucleus is larger and darker
  • irregular shape
  • don’t produce all the proteins they need to function correctly
  • have different antigens
  • they divide more frequently
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20
Q

methylation is…

A

adding a CH3 group onto something

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21
Q

methylation can control wether…

A

a gene is transcribed is transcribed and translated

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22
Q

hypermethylation is when….

A

methylation happens too much

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23
Q

hypomethylation is when…

A

methylation happens too little

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24
Q

abnormal methylation can cause…

A

tumors

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25
over exposure to oestrogen is thought to....
increase a womens chance of bresat cancer
26
the two types of risk factor are...
genetic environmental
27
screening can be used to..
look for cancer causing mutations in a persons DNA
28
stem cells are...
unspecialised cells that can develop into other types of cell
29
totipotent cells can...
mature into any type of body cell in an organism
30
pluoripotenet cells can...
mature into any type of cell in the body but not cells that make up the placenta
31
multipotent cells can...
differentiate into a few different types of cell
32
unitpotent cells can...
differentiate into only one type of cell
33
a cardiomyocyte is...
heart muscle cells that make up a lot of tissue in our heart
34
bone marrow transplants can be used to....
replace the faulty bone marrow in patients that produce abnormal blood cells
35
bone marrow transplamts can be used to treat...
leukaemia and lymphoma
36
bone marrow contains...
stem cells that can become specialised to form any type of body cell
37
what are the 3 sources of stem cell?
1. adult stem cells 2. embryonic stem cells 3. induced pluoripotent stem cells
38
pros and cons of adult stem cells
pros obtained from simple operation cons can only specialise into a limited type of cells (multipotent)
39
embryonic stem cells are obtained from...
embryos at an early stage of development
40
how old are the embryos when embryonic stem cells were obtained from then?
4 to 5 days
41
pros and cons of embryonic stem cells
pros can divide an unlimited amount of times and develop into all types of body cell cons ethical beliefs about killing an embryo
42
induced pluripotent cells (iPS) are created in...
the lab
43
how are iPS cells developed?
adult cells are made to express a series of transcription factors associated with stem cells that cause them to express genes associated with pluripotency
44
the benefits of stem cell therapy are
they could save lives they can improve quality of life could be used to grow a tissue or organ that the body won't reject
45
transcription factors are...
protein molecules that control the transcription of genes
46
the site where transcription factors bind to DNA is....
the promoter
47
transcription factors control expression by....
controlling the rate of transcription
48
activators are...
transcription factors that stimulate or increase the rate of transcription
49
repressors are....
transcription factors the inhibit or decrease the rate of transcription
50
how do activators stimulate or increase the rate of transcription?
they help RNA polymerase bind to the start of the target gene and activate transcription
51
how do repressors inhibit or decrease the rate of transcription?
they bind to the start of the target gene, preventing RNA polymerase from binding, stopping transcription
52
oestrogen binds to a transcription factor called an.....
oestrogen receptor
53
when oestrogen binds to a oestrogen receptor what is formed?
an oestrogen - oestrogen receptor complex
54
after an oestrogen-oestrogen receptor complex forms what happens?
it moves from the cytoplasm into the nucleus where it binds to specific DNA sites near the strat of the target gene
55
the oestrogen-oestrogen receptor complex can act as...
a repressor of transcription and an activator of transcription
56
RNAi molecules are...
small lengths of non-coding RNA
57
RNA interference is abbriviated to...
RNAi
58
what does RNAi do?
stops mRNA from target genes being translated into proteins
59
What does miRNA and siRNA stand for?
Micro RNA Small interfering RNA
60
How do miRNA and siRNA Differ?
miRNA isn't fully complementary to the mRNA, because it less specific than siRNA it can target more than one mRNA molecule
61
epigenetics is...
the process by which environmental factors cause heritable changes in gene function without changing DNA base sequence
62
what are the 2 epigenetic mechanisms used to control gene expression?
increased methylation of DNA decreased acetylation of histones
63
how does methlyation of DNA cause a gene to not be expressed?
increased methylation changes the DNA structure so the transcriptional machinery can't interact with the gene
64
histones are...
proteins that DNA wraps around to form chromatin which makes up chromosomes
65
how condensed the chromatin is affects the...
accessibility of the DNA and wether or not it can be transcribed
66
how can histones be epigenetically modified?
by addition or removal of acetyl groups
67
when histones are acetylated...
the chromatin is less condensed so the transcriptional machinery can access the DNA allowing genes to be transcribed
68
when acetyl groups are removed from histones...
the chromatin becomes highly condensed and genes in the DNA cannot be transcribed because the transcriptional machinery cannot physically access them
69
what enzyme is responsible for removing acetyl groups?
histone deacetylase
70
are epigenetic changes reversible?
yes
71
phenotype is...
the observable characteristics of an organism that is a result of the genotype and its environment

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