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mRNA Translation

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krabi's version from 2015-08-04 09:07

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Question Answer
How do you distinguish between the different kinds of RNA? (RMT)
rRNAIs actually part of the ribosome, so also has bits of protein. It supports the catalytic function of the ribosome. Transcription happens @nucleolus.
mRNA has a messenger role from the DNA because it translates the code to create proteins.
tRNAHas the translator role for the mRNA during protein production. Trasner RNA actually carries the amino acids over to the protein while it is being made.
What are the components of tRNA?Is made of RNA bits. Has three important components: 1) Amino acceptor Site 2) Anti-Codon site 3) bound by H.bonds made by DNA pol III
How is tRNA bonded?Stem and loop stabalized by H.bonds It has a pizza order receiving area for the complementary anti-codon which attaches itself to the bottom; The amino acids are bound at the top into the chain - is the pizza assembly factory
What do I need to know about Translation?Peptide bonds are unfavourable for energy (AG > 0), slow kinetics. Thus, requires High Activation energy. It is reaction coupled with AMP to Pi bonds are hydrolyzed
tRNA LOADING looks like what? linking sausages ie. amino acids
tRNA Step 1aa joins with AMP ⇒ aminoacyl AMP
tRNA Step 2pyrophosphate leaving group is hydrolyzed ⇒ 2 phosphates run away AG<0
tRNA Step 3unfavourable tRNA loading is driven forward
tRNA Step 4bond is broken between aa & tRNA ⇒ is the powering force for peptide bond formation ; the nitrogen of 1 aa will nucleophillically attach the carbonyl carbon of another aa
What is an Aminoacyl-tRNA Syntases in Translation?Aminoacyl tRNA synthetase attaches the appropriate amino acid onto its tRNA; Called "charging" or "loading" the tRNA with the amino acid. Once the tRNA is charged, a ribosome can transfer the amino acid from the tRNA onto a growing peptide, according to the genetic code. The actual attachment is called “amino acid activation”.
What is the Role of Aminoacyl?Thermodynamically activates the aa - the hydrolysis of the energetic bond between the aa and its very own tRNA actually drives protein synthesis. How? the N terminus of the incoming aa attaches the carboxyl group of the enemy aa. The attacker tRNA is the leaving group.
What is the Role of the Ribosome in Translation?Made of RNA and polypeptides; Has a 4th quat structure
What is the structureSediments at: 70S (bacteria) and 80S (euk); Has large and small subunits
In Translation, tRNA move along the APE site of the RobisomeA (amino acyl site) ⇒ P (peptidyl site) ⇒ E (exit site)
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Section

Question Answer
What is an Aminoacyl-tRNA Syntases in Translation?Aminoacyl tRNA synthetase attaches the appropriate amino acid onto its tRNA.
tRNA loading?Called "charging" or "loading" the tRNA with the amino acid. Once the tRNA is charged, a ribosome can transfer the amino acid from the tRNA onto a growing peptide, according to the genetic code. The actual attachment is called “amino acid activation”.
Importance of tRNA loading because1) Highly Specific aa delivery - can’t have mistakes 2) Thermodynamically activates the aa - the hydrolysis of the energetic bond between the aa and its very own tRNA actually drives protein synthesis.
How does it drive protein synthesis?the N terminus of the incoming aa attaches the carboxyl group of the enemy aa. The attacker tRNA is the leaving group.
What is the Role of the Ribosome in Translation?Made of RNA and polypeptides; Has a 4th quat structure; Sediments at: 70S (bacteria) and 80S (euk) w/large and small subunits
What is the start codon?AUG - start UN translating in August
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Question Answer
What is Eukaryotic TranslationSeveral ribosomes which are much larger (80S) & mRNAs must be spliced & capped pre-translation in nucleus
What is Bacterial TranslationAttaches to ribosomes and translation happens along w/transcription; Smaller ribosome = Several ribosomes play along ie. polycistronic
What is Shine Delgarno?Ribosome binding site - aka Shine Delgarno site
Initiation of Eukaryotic Translation?no Shine Delgardo complex, Kozak sequence, tRNA and mRNA bind to small subunit, Then large subunit binds
Initiation in PROkaryotic Translation?Formation of 70S Initiation complex
What powers prok. trans?Powered by 1 GTP molecule
What is the chem rx in prokaryotic translation?1st aminoacyl tRNA - initiator tRNA & Hydrogen bonds w/start codon fMet
Elongation of Prokaryotic TranslationAminoacyl tRNA enters A site (H.bonds w/2nd codon); Powered by hydrolysis of phosphate from G
Chem RX of ElongationPeptidyl transferase of large ribosome subunit catalyses bond w/fMet; (2nd aa acts as nucleophile - tRNA-fMet is leaving group)
Termination of Proaryotic TranslationStop codon Release factors enter A site.
What is the Chem Rx Termination of Proaryotic TranslationPeptidyl transferase hydrolyses bond between last tRNA and protein chain; Ribosome separates into large/small subunits and floats off into cytoplasm.
What is the BIGGEST difference between Euk & Pro TranslationEukaryotic and prokaryotic translation differ in the mechanism by which ribosomes recognize the 5’ end of mRNA
What is the BIGGEST difference between Euk & Pro TranslationProk.mRNA is recognized ⇒ by the ribosome using the Shine-Dalgarno sequence VS Euk. mRNA is recognized ⇒ via the 5’ cap that is added during post-transcriptional modification.
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