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biology year 2 > Mutations and Gene Expression > Flashcards

Mutations and Gene Expression Flashcards

1
Q

define stem cells?

A

cells that can divide and differentiate to become diff types of cell

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2
Q

totipotent stem cells

A

can divide and differentiate into any type of specialised cell

  • very early mammalian embryos
  • can form placenta cells
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3
Q

pluripotent stem cells

A

can differentiate into MANY types of specialised cell

  • embryo and adult cells
  • cant make placenta cells
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4
Q

multipotent stem cells

A

can differentiate into FEW types of specialised cell

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5
Q

unipotent stem cells

A

can differentiate into ONE type of specialised cell

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6
Q

what can a change in the internal enviro do?

A

affect expression of genes

cells = specialised (cant be reversed)

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7
Q

conditions within cells control what?

A

which genes expressed (transcribed and translated)

into proteins

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8
Q

what does RNAi do?

A

control gene expression by preventing translation

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9
Q

what is siRNA?

A
  • small interfering RNA
  • short stranded RNA
  • combines with proteins to = siRNA-protein complex
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10
Q

what does siRNA do?

A
  • siRNA = single stranded
  • has complementary base sequence to target mRNA
  • siRNA-protein complex breaks down mRNA into pieces
  • prevents translation
  • mRNA pieces recycled
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11
Q

what does microRNA do?

A
  • combines with protein = microRNA-protein complex
  • binds to mRNA by comp base pairing
  • less specific than siRNA - works on more than one mRNA
  • prevents translation - prevents ribosome attaching
  • mRNA stored / recycled
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12
Q

what are transcription factors

A

proteins that control the rate of protein synthesis by switching some genes on and other genes off

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13
Q

what are promoter regions

A

short sequence of DNA at start of gene

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14
Q

how transcription factors work?

A
  • TF move from cytoplasm to nucleus
  • binds to promoter region
  • activators - help RNA polymerase bind to gene (TRANSCRIBED)
  • repressors - prevent RNA polymerase binding to gene (NOT TRANSCRIBED)
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15
Q

what can transcription factors also be turned on / off by?

A

second messenger

cAMP

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16
Q

controlling TF

oestrogen example

A
  • oestrogen = steroid hormone
  • binds to receptor called oestrogen complex
  • forms oestrogen-oestrogen complex
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17
Q

define epigenetics?

A

changes to gene expression caused by enviro factors ( without changing base sequence of DNA)

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18
Q

what does epigenetics do?

A
  • controls gene expression by preventing transcription
  • can be inherited between gen
  • helps organisms respond to changes in enviro
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19
Q

More Methylation =

A

Terminates Transcription

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20
Q

what are CpG sites

A

where C and G next to each other in DNA

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21
Q

what do methylated CpG sites prevent?

A

transcription enzymes attaching (RNA polym)

transcription prevented

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22
Q

less acetylation of histones =

A

Terminates Transcription

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23
Q

what are histones

A

proteins that supercoil DNA into chromatin

24
Q

what does acetylation do?

A
  • acetyl groups make histones space out
  • allows transcriptional enzymes (RNA polym) attach
  • gene expressed
  • enzymes remove acetyl groups
  • prevent transcription
25
Q

bone marrow transplant

A
  • contains multipotent stem cells
  • can differentiate into RBC and WBC
  • replace faulty bone marrow with new bone marrow = forms new healthy cells
26
Q

growing new organs

A
  • no donor needed
  • induced pluripotent stem cells
  • iPS have same antibodies - no organ rejection
27
Q

advantages of growing new organs and transplants

A
  • saves lives
  • improves quality of life
  • prevents suffering
28
Q

ethical issues to growing new organs and transplants

A
  • stem cells taken from IVF embroys which could develop into embryos if implanted
  • from fertilisation zygote has right to life

(as you use unfertilised eggs which are triggered to divide)

  • adult stem cells not pluripotent

iPS may be future sol

29
Q

what can transcription be controlled by

A

methylation

30
Q

hypermethylation

A
  • TSG
  • protein not transcribed
  • uncontrolled cell division
31
Q

hypomethylation

A
  • proto-oncogenes
  • more proteins transcribed
  • uncontrolled cell division
32
Q

describe benign tumours

A
  • non-cancerous
  • grow slowly
  • harmless
  • can become malignant
33
Q

describe malignant tumours

A
  • grow quickly
  • destroy tissue
  • can break up and spread to blood / lymphatic system
34
Q

describe what tumour cells look like

A
  • mitosis - more cells dividing
  • nuclei - large and odd shaped - more than 1
  • cell shape = irregular
  • function - loss of normal function
  • arrangement - disorganised
35
Q

how can high levels of oestrogen cause some types of breast cancer

A
  • binds to proteins = transcription factor
  • called oestrogen-oestrogen receptor complex
  • increases rate of cell division
  • inc rate of dna rep
  • inc chance of mutations
  • inc chance of cancer
36
Q

define mutation

A

change to base sequence of DNA

37
Q

no change to amino acid sequence

A
  • amino acid coded for by more than triplet
  • DNA = degenerate
38
Q

change to single amino acid

A
  • changes one DNA triplet
  • changes translation of amino acid
  • changes primary structure
  • changes hydrogen/ionic bonding
  • changes tertiary structure of protein
39
Q

change to many sequence of amino acids

A
  • frame shift changes sequence of all following dna triplets
  • changes all following amino acid sequence
  • changes primary structure
  • changes hydrogen/ionic bonding
  • changes tertiary structure
40
Q

mutations that change sequence of DNA

A
  • addition
  • duplication
  • deletion
41
Q

define induced pluripotent stem cells

A

treating unipotent stem cells with transcription factors that make them pluripotent

42
Q

iPS

A
  • use modified virus as vector
  • virus inserts TF genes from pluripotent stem cells into DNA of unipotent stem cells
  • TF expressed
  • make totipotent stem cells this way
43
Q

embryonic stem cells

A
  • embryos made in lab by IVF
  • pluripotent stem cells removed after few days
  • embryo destroyed
  • pluripotent stem cells differentiate into all types of body cells
44
Q

adult stem cells

A
  • taken from adults in operation
  • adult stem cells = multipotent
  • less useful for medicine as cant form every type of cell
45
Q

how do mutations occur

A

spontaneous mistakes during dna rep

46
Q

what do mutagenic agents do

A

increase rate of mutations

47
Q

base analogs

A

chemical that can substitute for normal nucleotide base

SUBSTITUTION MUTATION

48
Q

radiation

A

change structure of dna

UV, IONISING

49
Q

change dna bases

A

chemicals that react with dna to change its structure

SUB / DELETION

50
Q

define substitution

A

one base swapped for another

(no change, dna = degenerate)

51
Q

define addition

A

extra base added

52
Q

define deletion

A

base removed

  • causes frame shift
  • all following triplets in sequence affected
53
Q

define inversion

A

sequence of bases reversed

  • no change
  • change few AA
  • no frame shift
54
Q

define duplication

A

one / more bases repeated

55
Q

define translocation

A

sequence of DNA moved from one part of genome to another part of genome

(in same chromosome / to diff chromosome)

56
Q
A

biology year 2 (29 decks)

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