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BIOLOGY PAPER 2 > CELLULAR CONTROL > Flashcards

CELLULAR CONTROL Flashcards

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1
Q

define mutation

A

a random or spontaneous change to the nucleotides in the base sequence of DNA

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2
Q

missense

A

change to a single nucleotide

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3
Q

nonsense

A

stops translation prematurely

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4
Q

frameshift

A
  • insertion or deletion of a nucleotide
  • sequence is read in codons of 3 nucleotides so the subsequent codons are read incorrectly as translation machinery cannot identify error
  • wrong amino acids coded for so different protein produced
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5
Q

insertion

A

nucleotide incorporated into base sequence during DNA replication

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6
Q

deletion

A

nucleotide missed or absent during replication

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7
Q

substitution

A

nuceleotide incorrectly swapped during replication
- can be silent as code is degenerate
- but could swap with stop codon

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8
Q

what is a transcription factor?

A

proteins that control transcription by regulating gene expression, binding to DNA and controlling protein synthesis

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9
Q

why is controlling transcription important?

A
  • prevents tumour growth
  • conserves energy
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10
Q

describe the regulatory mechanism at transcriptional level

A
  • during mRNA production
  • cell division
  • lac operon
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11
Q

describe the regulatory mechanisms at post transcriptional level

A
  • after mRNA production
  • editing of primary mRNA
  • removal or introns to produce mature mRNA in a process called splicing
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12
Q

describe the regulatory mechanisms at post translational level

A
  • after protein synthesis
  • addition of non protein groups
  • folding & shortening of proteins
  • binding of cAMP to activate proteins
  • adrenaline binds to receptors on surface cell membranes to form a hormone receptor complex which activates adenylate cyclase which converts ATP to cAMP
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13
Q

define operon

A

a set of simultaneously controlled genes which are either all expressed or not

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14
Q

define repressor

A

protein that inhibits transcription by binding to a promoter so that RNA polymerase cannot bind

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15
Q

define promoter

A

region on operon which is a sequence of DNA where RNA polymerase binds to signal the start of transcription

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16
Q

define operator

A

a protein that inhibits transcription

17
Q

what is lac operon?

A

a set of 3 genes (Y,Z,A) which collectively aid lactose digestion in e coli

18
Q

when is lac operon used?

A

when lactose is present

19
Q

why is glucose a favourable respiratory substrate?

A
  • requires less energy to be broken down by bacteria
  • due to the OH/H bonds which contain energy
20
Q

describe what happens when lactose is absent

A
  • lacL produces lots of repressor
  • repressor binds to operator on lac operon and blocks promoter
  • this prevents RNA polymerase binding
  • so transcription is inhibited as structural genes are switched off
21
Q

describe what happens when lactose is present

A
  • lactose binds to the repressor and changes its shape
  • RNA polymerase binds to promotor
  • transcription is initiated
22
Q

what is the role of cAMP?

A

increases rate of transcription as it is too slow to produce sufficient enzymes
- CRP must bind to it first

23
Q

homeobox genes

A
  • sequences of genes which code for transcription factors & regulate gene expression
  • arranged into hox clusters
  • responsible for body feature development in the early embryo
  • similar and highly conserved
24
Q

hox genes

A
  • set of homeobox genes
  • produce proteins involved in body feature position
  • affected by internal and external stimuli
25
Q

what is gene expression?

A

conversion of information encoded into a gene into a functional gene product eg RNA

26
Q

give 5 reasons for the importance of mitosis

A
  • growth
  • repair
  • asexual reproduction
  • stem cell increase
  • body plan development
27
Q

what is apoptosis?

A
  • programmed cell death
  • removal of unwanted cells if there is an error in replication or if cell is old
28
Q

describe the mechanism of apoptosis

A
  • digest cell contents
  • cytoplasm shrinks and forms projections called blebs
  • blebs become apoptotic bodies which contain organelles
  • blebs are engulfed by phagocytosis

BIOLOGY PAPER 2 (8 decks)

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