Protein synthesis

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  • Created by: Sarah
  • Created on: 19-05-17 19:02
what is the nissl substance?
large granular body found in neurons, granules of RER surrounded by rossettes of ribsomes
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what is there most of, dna, mRNA or proteins?
proteins
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what is sometimes the end product?
RNA
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differences between RNA and DNA?
ribose- RNA, DNA- deoxyribose, uracil in RNA replaces thymine
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what does transcription use?
RNA polymerase
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what happens in transcription?
gene to be transcribed dips into nucleoulos H bonds break, RNA polymerase adds activated RNA nucleotides
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how many possible combinations of codons are there?
64 (4^3)
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what is the adaptor in pro syn?
tRNA
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what is the tRNA?
amino-acyl tRNA with amino acid attached
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if the codon (on mRNA was UUC) what would it be on the tRNA anticodon?
AAG
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what reads the mRNA code?
the ribosome
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what is the ribosome?
a large RNA-protein complex
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which sites are in the large and small subunits?
PA
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what is the order of the sites
EPA
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what is the A site?
amino-acyl tRNA
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what is the P site?
peptidyl-tRNA
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what is aminoacyl tRNA?
tRNA that has its amino acid chemically bonded (elongation factor goes with to ribosome)
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what is the petidyl tRNA site?
the site which is most often carrying the growing peptide chain
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what is the 3 steps in prokaryotic translation?
1) incoming aa-TRNA binds to A-site 2) aa tRNA occupies P site as large and small subunits undergo conformational change as new peptide bond is formed 3) mRNA moves 3 nucleotides thro small subunit spent tRNA ejected
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what end of the peptide is the peptidyl tRNA attched to?
C terminus of growing polypetide chain
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what is the incoming aa-tRNA associated with?
elongation factor (EF-TU-GTP)
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what is EF-TU-GTP?
a GTPae, a GTP hydrolysing protein
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what promotes EF-TU-GTPase activity?
correct base pairing
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what happens if the base pairing is correct for EF-TU-GTP?
GTPase activity, GDP bound borf of EF-TU dissociates from complex and aa-tRNA is captured
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what happens if theres incorrect base-pairing?
no GTPase ativity, no aa-captured
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where does elongation factor EF-G in GTP-bound form bind to?
close to A site
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EF-G promotes what?
tRNAas into hybrid state (A/P and P/E)
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what happens when GTP hydrolysis by EF-G?
movement of tRNAs into P and E by massive shape change
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what does translation always begin with?
AUG- methionine
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what does itRNA carry?
AUG - methionine (or f-met in bacteria)
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what is loaded in the small subunit with the iniator tRNA?
eukaryotic initiation factor elf-2
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what end does the itRNA meet?
5' cap end mRNA
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how does the ribosome subunit bind with the 5' capped mRNA?
using elFs
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what does the small ribosomal subunit start doing once its bound to the 5' capped mRNA?
scanning for AUG
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what happens when it finds AUG?
eLFs dissociate (GTP-> GDP) and the large subunit asociates
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What site does the iniator tRNA bind to?
P site
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where does the aa-tRNA then enter?
A site
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what terminal is the peptide synthesised from?
N to C terminal end, add tRNA to C terminal
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how do you terminate protein synthesis?
stop codons not recognised by tRNA, release factor binds to A site with stop codon in, petidyl transferase catalyses transfer of water to C terminus terminates
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where does the release factor bind to?
A site
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why is peptidyl transferase adding water important?
results in dissociation of peptide from ribosome
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what does the release factor moving from the A to P site cause?
ribosome disassembly
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why can side effects occur with antibiotics?
siilarity bewteen mito and bacterial syntheiss
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what do antibiotiocs do?
selectively inhibit bacteria protein synthesizing machinery
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Card 2

Front

what is there most of, dna, mRNA or proteins?

Back

proteins

Card 3

Front

what is sometimes the end product?

Back

Preview of the front of card 3

Card 4

Front

differences between RNA and DNA?

Back

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Card 5

Front

what does transcription use?

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