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bio > d1.2 protein synthesis > Flashcards

d1.2 protein synthesis Flashcards

1
Q

sense strand

A

actually contains the genetic material for the polypeptide

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2
Q

antisense strand

A

complimentary strand
- not codable in the 5’ to 3’ direction

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3
Q

mRNA vs sense strand

A

mRNA is a copy of the sense strand (T is replaced by U)

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4
Q

gene

A

segment of dna that contains coded information for synthesising a polypeptide molecule

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5
Q

what does ribosome convert (what to what)

A

dna to amino acid

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6
Q

what is the only thing that is copied

A

gene segment

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7
Q

start codon

A

AUG

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8
Q

what can cells do through gene expression

A

cells can specialise into different types

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9
Q

what does cell specialisation affect

A

whether or not a gene will be transcribed for ribosomes to create the necessary polypeptide

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10
Q

transcription

A

first stage of gene expression, key stage at which expression of a gene can be switched on and off

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11
Q

how does the dna fit in the nucleus

A

wrapped around histone to form nucleosome

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12
Q

how does nucleosome affect gene expression

A

by prompting or limiting dna transcription

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13
Q

what does a condensed chromatin mean

A

no genes are expressed since dna transcription is inhibited

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14
Q

what does an open chromatin mean

A

genes are expressed since it promotes dna transcription

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15
Q

what does the rna polymerase attach to + what does it do

A
  1. unzip the double helix
  2. attach onto the antisense strand (template strand)
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16
Q

why does the dna polymerase attach to the antisense strand

A

as it moves, it copies and makes rna that is complementary to the antisense strand

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17
Q

after transcription what does the ribosomes do (+ what do they use)

A

uses tRNA to synthesise the polypeptide using the mRNA

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18
Q

what do tRNA contain

A

anticodon that is complementary to the codon in the mRNA

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19
Q

what do ribosomes do after transcription at the 3’ end

A

carries the amino acid that the codon codes for

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20
Q

2 types of ribosomes

A
  1. free ribosomes
  2. bound ribosomes
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21
Q

where will all mRNA go to first

A

free ribosomes

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22
Q

how to tell if a gene is expressed

A

if it is condensed, its not expressed

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23
Q

how is the mRNA identical to the sense strand except T to U

A

mRNA uses RNA polymerase which attaches to the antisense strand

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24
Q

what would happen is the ribosome is bound on the rough er

A

polypeptide would go outside of the cell through exocytosis

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25
Q

dna structure of tRNA

A

clover leaf

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26
Q

brief process of translation

A
  1. initiation
  2. elongation
  3. termination
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27
Q

detailed process of initiation

A
  • mRNA enters the small unit of the ribosome
  • tRNA carrying Met will bind to start codon
  • large subunit of ribosome binds and the tRNA will fit into the p site
28
Q

detailed process of elongation

A
  • another tRNA binds to the next codon at the A site
  • amino acid in P site will form a peptide bond with the amino acid of the A site
  • ribosome will move from 5’ to 3’ to the next codon
  • tRNA in the E site leaves
  • repeats until the stop codon hits the A site
29
Q

detailed process of termination

A
  • when a stop codon enters A site, translation terminates
  • ribosome detaches
  • polypeptide detaches from the tRNA
30
Q

what does the polypeptide need to do in order for it to be functional

A

fold according to its properties

31
Q

3 types of point mutation affecting protein structure

A
  1. base substitution
  2. base deletion
  3. base addition
32
Q

which point mutation has the least impact + why

A

base substitution
doesnt change all the codons after it (reads in triples)

33
Q

how does the different amino acid in sickle cell affect the chemical properties

A

non polar
- hydrophobic so it wants to be on the inside

34
Q

codon for Met (the starting codon)

A

AUG

35
Q

codons for the stop codon

A
  1. UAG
  2. UAA
  3. UGA
36
Q

how to determine where to start reading a codon

A
  • the first few codons doesnt have a stop codon
37
Q

what do non-coding sequences in dna mean

A

do not code for polypeptides

38
Q

functions of non-coding sequences in dna

A
  1. telomeres
  2. introns
  3. base sequences
39
Q

what are telomeres

A

structures that form the end of chromosomes in eukaryotes

40
Q

what are introns

A

non coding regions within a gene that needs to be edited out

41
Q

what do only eukaryotes have

A

introns

42
Q

what are base sequences

A
  • can be transcribed to produce transfer rna (tRNA), ribosomal RNA (rRNA) that makes up part of a ribosome (ribosome is made up of RNA and proteins
  • base sequences used to regulate gene expression (eg. promoters, enhancer and silencer)
  • affects gene even tho doesnt code for polypeptide itself
43
Q

what proteins affects dna transcription

A

enhancer and silencer regions

44
Q

what is the promoter proximal elements

A

proteins need to bind there to allow for transaction to start

45
Q

mechanism of silencer

A

bind and stops the promotor or rna polymerase to bind

46
Q

what does activated protein do

A

enhances transcription

47
Q

y is regulation needed

A

so not all resources are used up

48
Q

why do only eukaryotes need to do post transcription processing

A

have introns to be cut out

49
Q

process of post-transcriptional processing

A
  1. splicing
  2. alternative splicing
  3. 5’ cap
  4. poly A tail
50
Q

splicing

A

removal of introns using splicesome (small nuclear ribonucleoprotein)

51
Q

why is alternative splicing needed

A

to make variations of polypeptide for different functions

52
Q

function of 5’ cap

A
  • prevents breakdown of the mRNA
  • helps regulate the export out of the nucleus
  • promotes translation
53
Q

function of poly A tail

A
  • prevents breakdown of mRNA
  • keeps mRNA stable
  • results in mature mRNA
54
Q

conjugated proteins

A

quaternary + non polypeptide component

55
Q

name of sequence that tells ribosomes to go to rough er

A

signal sequence

56
Q

why does the protein have to go to the rough er

A

so exocytosis can occur

57
Q

what is the signal sequence not a part of

A

insulin

58
Q

prepoinsulin

A

chop off signal sequence

59
Q

3 parts of preproinsulin

A
  1. b-b chain
  2. a-a chain
  3. connecting polypeptide
60
Q

how does the preproinsulin start folding

A
  • r group
  • disulphide birdges between cystine
61
Q

what are used to modify the polypeptide

A

protease

62
Q

why might proteins no longer be needed

A
  1. reaction ended
  2. proteins changed due to denaturation/mis-folding
  3. changed due to free radicals or other reactive chemicals
63
Q

name of recycling protein

A

proteaosomes

64
Q

what are proteaosomes

A

molecular machine that removes and recycles proteins into amino acids

65
Q

what tags the short protein sequences

A

ubiquitin

66
Q

what is needed to break down protein

A

atp

67
Q

role of ribosomes in translation

A

translation is the production of polypeptides/proteins
b. mRNA binds to the ribosome
c. tRNA binds to the ribosome
d. at the site where its anti-codon corresponds to the codon on the mRNA
OWTTE
e. amino acids of «consecutive tRNAs» bind by a peptide link «in the ribosomes»
f. the ribosome moves along the mRNA
OR
continues with elongation of polypeptide chain

bio (23 decks)

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