Translation Flashcards
Where does translation occur?
Cytoplasm, at ribosome
What is the start codon?
Point at which ribosome starts translation; AUG
What is always the first amino acid in a polypeptide chain?
Methionine
What are the three stop codons?
UAA, UGA, UAG
Where are the components of the ribosome sythesised?
In the nucleus; is combo of protein and rRNA
What are the subunits of the ribosome?
40s and 60s; form an 80s ribosome. Are named for their ultracentrifugation sedimentation size
What are polysomes?
Multiple ribosomes formed around an length of mRNA; allows the synthesis of more proteins than the mRNA that encodes it; overcomes the set rate of translation by each ribosome
What are features of tRNA?
Small (<100 bases) RNA molecule; clover-like structure, with anti-codon; terminal tri-nucleotide (3’ end) binds to matching amino acid
How is tRNA activated and bound to an amino acid?
Aminoacyl-tRNA ligases (activating enzymes) bind tRNA and amino acid, using ATP in the process; each amino acid has specific tRNA and activating enzyme (20 of each)
Outline the process of translation.
Initiation: 40s binds to tRNA with methionine; initiator tRNA finds 5’ cap of mRNA and finds and binds to start codon; signals to 60s to build complete ribosome –> initiation complex. Elongation: tRNA enters aminoacyl tRNA site (A site) of ribosome; amino acid in A site forms peptide bond with amino acid held in peptidyl-tRNA site (P site); amino acid moves from P site to exit site, where tRNA dissociates from amino acid. Termination: ribosome reaches stop codon, for which there is no matching tRNA; release factor matches stop codon and enters A site; release factor cannot bind to polypeptide chain, so when tRNA moves into E site, polypeptide chain is released; ribosome complex breakdowns.
What is protein turnover?
Process of analysing: total amino acid pool; rate at which proteins are synthesised; rate at which proteins degrade. Need to main amino acid pool
How does exercise affect protein synthesis?
Affects stimuli for transcription, having knock-on effect on translation and protein synthesis
What type of resistance exercise stimulates more muscle protein synthesis: low load and high volume, or high load and low volume?
Low-load, high volume resistance training stimulates higher muscle protein synthesis
Which type of exercise increases rate of upregulation of muscle proteins more: resistance or endurance?
Resistance training increases upregulation of muscle proteins, whilst endurance didn’t have much effect
Which type of exercise increases rate of upregulation of mitchondria more: resistance or endurance?
Endurance training increased upregulation of mitochondria more; but in untrained people, a massive increase was seen for both endurance and resistance training
How can response to exercise be manipulated?
Diet alters protein synthesis: essential amino acids and dietary proteins can increase protein synthesis; different protein sources provides different results; combining protein ingestion with resistance training shows greater anabolic effects
What protein source increases protein synthesis most?
Whey
What protein source increases protein synthesis least?
Casein
What effect does soya have on protein synthesis?
Has greater effect than casein, but not as much as whey
Which source of protein in milk is digested quicker?
Whey
