Translation Flashcards
pathway to making a protein:
DNA -> mRNA -> tRNA -> protein
process of decoding the mRNA into a polypeptide chain
translation
final step of the central dogma
translation
where does translation occur?
free ribosomes and ribosomes in ER
ribosomes are composed of:
60% proteins, 40% rRNA
two sites of attachment for tRNA
P and A
how many mRNA and tRNA binding sites are there?
1 mRNA binding site
3 tRNA binding sites
holds the tRNA carrying the next amino acid to be added
A site
holds the tRNA carrying the growing polypeptide chain
P site
where the tRNA leaves the ribosome
E site
where is amino acid attached?
to the 2’ or 3’ carbon of the ribose at the 3’ end of tRNA
how many possible codons in the genetic code?
64
translation initiation factors:
[mICs]
mRNA
Initiation factors
Charged tRNA
small ribosomal unit
binds to the 30s (small) ribosomal subunit, allowing it to bind to mRNA
eIF3
recognizes the 5’ end of the mRNA
eIF4
forms a complex with the charged tRNA and GTP
eIF2
helps the other IF to stabilize the 30s ribosomal subunit
eIF1
what allows the initiation complex to join the 50s (large) ribosomal unit?
the hydrolyzation of GTP to GDP + P
elongation steps:
[CPT]
Codon recognition
Peptide bond formation
Translocation
H bonds form between the mRNA and tRNA
codon recognition
polypeptide chain is transferred to tRNA at the A-site; involves the carboxyl end
peptide bond formation
ribosome moves tRNA from P to E site (leaves ribosome); tRNA from A to P site (ready for next polymerization)
translocation
A site becomes empty
translocation
Ochre
UAA
Amber
UAG
Opal
UGA
catalyze the cleavage of the bonds between the polypeptide and tRNA
release factor
adds water molecule instead of amino acid
release factor
links amino acids in translation
peptide bond
