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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
Q

over exposure to oestrogen is thought to….

A

increase a womens chance of bresat cancer

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26
Q

the two types of risk factor are…

A

genetic
environmental

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27
Q

screening can be used to..

A

look for cancer causing mutations in a persons DNA

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28
Q

stem cells are…

A

unspecialised cells that can develop into other types of cell

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29
Q

totipotent cells can…

A

mature into any type of body cell in an organism

30
Q

pluoripotenet cells can…

A

mature into any type of cell in the body but not cells that make up the placenta

31
Q

multipotent cells can…

A

differentiate into a few different types of cell

32
Q

unitpotent cells can…

A

differentiate into only one type of cell

33
Q

a cardiomyocyte is…

A

heart muscle cells that make up a lot of tissue in our heart

34
Q

bone marrow transplants can be used to….

A

replace the faulty bone marrow in patients that produce abnormal blood cells

35
Q

bone marrow transplamts can be used to treat…

A

leukaemia and lymphoma

36
Q

bone marrow contains…

A

stem cells that can become specialised to form any type of body cell

37
Q

what are the 3 sources of stem cell?

A
  1. adult stem cells
  2. embryonic stem cells
  3. induced pluoripotent stem cells
38
Q

pros and cons of adult stem cells

A

pros
obtained from simple operation
cons
can only specialise into a limited type of cells (multipotent)

39
Q

embryonic stem cells are obtained from…

A

embryos at an early stage of development

40
Q

how old are the embryos when embryonic stem cells were obtained from then?

A

4 to 5 days

41
Q

pros and cons of embryonic stem cells

A

pros
can divide an unlimited amount of times and develop into all types of body cell
cons
ethical beliefs about killing an embryo

42
Q

induced pluripotent cells (iPS) are created in…

A

the lab

43
Q

how are iPS cells developed?

A

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
Q

the benefits of stem cell therapy are

A

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
Q

transcription factors are…

A

protein molecules that control the transcription of genes

46
Q

the site where transcription factors bind to DNA is….

A

the promoter

47
Q

transcription factors control expression by….

A

controlling the rate of transcription

48
Q

activators are…

A

transcription factors that stimulate or increase the rate of transcription

49
Q

repressors are….

A

transcription factors the inhibit or decrease the rate of transcription

50
Q

how do activators stimulate or increase the rate of transcription?

A

they help RNA polymerase bind to the start of the target gene and activate transcription

51
Q

how do repressors inhibit or decrease the rate of transcription?

A

they bind to the start of the target gene, preventing RNA polymerase from binding, stopping transcription

52
Q

oestrogen binds to a transcription factor called an…..

A

oestrogen receptor

53
Q

when oestrogen binds to a oestrogen receptor what is formed?

A

an oestrogen - oestrogen receptor complex

54
Q

after an oestrogen-oestrogen receptor complex forms what happens?

A

it moves from the cytoplasm into the nucleus where it binds to specific DNA sites near the strat of the target gene

55
Q

the oestrogen-oestrogen receptor complex can act as…

A

a repressor of transcription
and an activator of transcription

56
Q

RNAi molecules are…

A

small lengths of non-coding RNA

57
Q

RNA interference is abbriviated to…

A

RNAi

58
Q

what does RNAi do?

A

stops mRNA from target genes being translated into proteins

59
Q

What does miRNA and siRNA stand for?

A

Micro RNA
Small interfering RNA

60
Q

How do miRNA and siRNA Differ?

A

miRNA isn’t fully complementary to the mRNA, because it less specific than siRNA it can target more than one mRNA molecule

61
Q

epigenetics is…

A

the process by which environmental factors cause heritable changes in gene function without changing DNA base sequence

62
Q

what are the 2 epigenetic mechanisms used to control gene expression?

A

increased methylation of DNA
decreased acetylation of histones

63
Q

how does methlyation of DNA cause a gene to not be expressed?

A

increased methylation changes the DNA structure so the transcriptional machinery can’t interact with the gene

64
Q

histones are…

A

proteins that DNA wraps around to form chromatin which makes up chromosomes

65
Q

how condensed the chromatin is affects the…

A

accessibility of the DNA and wether or not it can be transcribed

66
Q

how can histones be epigenetically modified?

A

by addition or removal of acetyl groups

67
Q

when histones are acetylated…

A

the chromatin is less condensed so the transcriptional machinery can access the DNA allowing genes to be transcribed

68
Q

when acetyl groups are removed from histones…

A

the chromatin becomes highly condensed and genes in the DNA cannot be transcribed because the transcriptional machinery cannot physically access them

69
Q

what enzyme is responsible for removing acetyl groups?

A

histone deacetylase

70
Q

are epigenetic changes reversible?

A

yes

71
Q

phenotype is…

A

the observable characteristics of an organism that is a result of the genotype and its environment

A Level Biology (19 decks)

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