Unit 02.3: Translation Flashcards
(44 cards)
which a^2 are negatively charged?
aspartate and glutamate
which structure on aspartate and glutamate causes them to be negatively charged?
the carboxylic acid on the R-grp
which a^2 are positively charged?
lysine, arginine, histidine
which structure on lysine, arginine and histidine causes them to be positively charged?
amino grp on R-grp
which a^2 are polar uncharged
serine, threonine, tyrosine, cysteine, asparagine, glutamine
what is the only a^2 that can make covalent bonds?
cysteine
who proposed the one gene one polypeptide hypothesis?
beadle and tatum
what are synonymous codons?
multiple codons that code for the same amino acid
the genetic code is:
universal, non-ambiguous, redundant/degenerate, non-overlapping
what are the 2 a^2 that only have one codon coding for them? what are their codons?
methionine (AUG) and tryptophan (UGG)
if the mRNA codon is read 5’ - 3’, what direction is the tRNA anticodon read in?
3’ - 5’
who figured out that the genetic code is non overlapping?
crick and brenner
who deduced the codon sequence for amino acids via their trial and error experiments?
nirenberg and matthaei
who discovered the first top codon in 1965?
sydney brenner
what is the purpose of transfer RNAs (tRNAs)?
to bring a^2 to codons during translation
describe the structure of tRNA
- a cloverleaf shape with 4 double helix stems, 3 of which lead to single stranded loops
- bottom loop contains anti codon (3’ to 5’), with the “wobble” position on the 3’ end of the anticodon
- on the top, we have a 5’-CCA-3’ sequence that allows for the binding of the a^2
describe the function of the “wobble” position in tRNA
the position on the 5’ end of the tRNA anticodon that allows for the 3’ position on the codon to not be complimentary
basically it doesn’t matter what the third nucleotide is for the most part, the tRNA will let it bind as most codons with same first two letters code for the same a^2
what does it mean when a tRNA is charged?
it has an a^2 attached
how many aminoacyl-tRNA synthetases are there?
20
describe the process by which tRNAs get charged.
- carboxyl grp of a^2 reacts with a-phosphate of ATP forming 5’-aminoacyl-AMP, releasing a pyrophosphate.
- amino acid is attatched to the adenosine in the 5’-CCA-3’ sequence of tRNA, releasing the AMP
what are the 3 common functions of ribosomes?
- bind mRNA and identify start codon for translation
- facilitate complimentary base-pairing between mRNA codons and tRNA anticodons
- catalyze peptide bond formation
what subunits make up a prokaryotic ribosome?
50s large subunit + 30s small subunit = 70s ribosome
what subunits make up a eukaryotic ribosome?
60s large subunit + 40s small subunit = 80s ribosome
describe the A-site of the ribosome. what is its function?
the first place the tRNA goes! binds incoming charged tRNA.
