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Biology Hope > cellular control > Flashcards

cellular control Flashcards

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1
Q

what is nonsense

A
  • mutation results in one of the three stop codons
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2
Q

what is missense

A

results in different amino acid sequence being coded for

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3
Q

what is silent

A

different codon
same amino acid is coded for

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4
Q

what is insertion

A

addition of a nucleotide

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5
Q

what is deletion

A

nucleotide removed

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6
Q

what is frame shift

A

causes all further amino acids to be changed including start and stop codons

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7
Q

what are the effects of mutations

A

Neutral - normal functioning proteins synthesised - phenotype unchanged

Harmful = proteins not synthesised and not functional - phenotype negatively impacted

Beneficial = protein synthesised with a new and useful characteristic in phenotype

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8
Q

what are the causes of mutations

A
  • occur naturally and spontaneously during DNA replication but appearnace increased by mutagens
  • x-rays, high energy radiation, chemicals in cigarettes
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9
Q

how is a gene switched off

A
  • site on the transcription factor binds to DNA and is blocked by an inhibitor
  • prevents transcription
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10
Q

how are genes turned on

A
  • hormones activate transcription factors
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11
Q

what are transcription factors

A
  • proteins move in from the cytoplasm and bind to DNA at the start of target genes
  • activators
  • repressors
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12
Q

how do transcription factors control gene expression at the transcriptional level

A
  • altering rate of transcription of genes
  • controlled by transcription factors
  • shape of a transcription factors determines whether it can bind to DNA or not
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13
Q

what are the features of a operon

A
  • structural gene codes for useful proteins
  • control elements = promotor (RNA polymerase binds) and operator (transcription factor binds to)
  • regulatory gene - codes for activator or repressor
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14
Q

the lac operon in E.Coli

A
  • E.Coli respires glucose but can use lactose

Lactose not present
- regulatory gene produces lac repressor
- transcription factor that binds to operator site when there is no lactose
- blocks transcription as RNA polymerase cannot bind

Lactose Present
- lactose binds to repressor
- repressor shapes changed and no longer binds to operator site
- RNA polymerase begins transcription of structural genes

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15
Q

how is mRNA edited at the post-transcription level

A
  • introns and exons copied into mRNA called pre-mRNA
  • introns removed from primary mRNA by splicing by a spliceosome
  • introns removed and exons joined forming mature mRNA and left in nucleus
  • mature mRNA leaves nucleus for translation
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16
Q

how does CAMP activate proteins at the post-translational level

A
  • protein activation is controlled by hormones and sugars
  • molecules work by binding to cell membranes and triggering production of CAMP inside the cell
  • CAMP activates proteins inside the cell by altering the 3D structure

PKA is an enzyme made of 4 sub-units
when CAMP isn’t bound the four units are bound together and inactive

17
Q

what are body plans

A

general structure of an organism

18
Q

what are homeobox genes

A
  • sequence of 180 base pairs found within genes in regulating anatomical development in plants, animals, fungi
19
Q

what are hox genes

A
  • subset of homeobox genes
  • involved in formation of anatomical features of an animal
20
Q

homeodomain proteins

A
  • coded for by hox genes
  • act as transcription factors to activate, repress genes, regulate mitosis, apoptosis and the cell cycle
21
Q

how do hox genes control development

A
  • homeobox sequences code for homeodomain proteins
  • homeodomain binds to specific sites on DNA enabling protein to work as a transcription factor
  • proteins bind to DNA at the start of developmental genes, activating or repressing transcription
  • alter the production of proteins
22
Q

what is apoptosis

A
  • programmed cell death
  • series of biochemical events leading to orderly cell death
  • too much = cell loss
  • too little = tumours
23
Q

what are the events of apoptosis

A
  • enzymes inside the cell breakdown important cell components such as proteins and DNA
  • cell contents begin to break up and shrink into fragments
  • fragments engulfed by pathogens and digested
24
Q

how is apoptosis controlled

A
  • regulated by hox genes

Internal
- damage to DNA detected in the cell cycle
- genes expressed that cause the cycle to stop
- release of hormones

External
- change in light intensity or temperature
- pathogen attack
- lack of nutrients
- drugs = thalidomide

Biology Hope (26 decks)

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