translation Flashcards
where does translation take place in eukaryotic cells
cytoplasm
describe what codons and anti-codons are and how they interact during translation
a codon is a triplet of nucleotides on the mature mRNA strand
an anti-codon is a triplet of nucleotides on a tRNA molecule
during translation the anti-codons form base pairs with the complimentary codons
what is meant when its said that the genetic code is degenerate and unambiguous
degenerate = many amino acids have more then one codon that can code for it unambiguous = each codon codes for only one amino acid(or a stop)
describe the role of aminoacyl-tRNA synthetases
they bind amino acids to their corresponding tRNA molecule(s), there is at least one for every amino acid(highly specific), ATP provides energy to make covalent bonds
describe the structure of ribosomes, including the names of each of its tRNA binding sites
ribosomes contain 4 rRNA molecules as subunits, 3 large and 1 small
they have 3 tRNA binding sites E,P and A = Exit, Peptidyl and Aminoacyl
explain the process of initiation of translation
requires initiation factors (IFs), and GTP for energy
small ribosome subunit binds to 5’ end of mRNA, moves along mRNA until start codon found, special initiator tRNA base-pairs with start codon, large subunit joins assembly line and initiator tRNA is located at P site
explain the process of elongation of translation
an elongation factor(EF) brings next aminoacyl-tRNA to the A site of ribosome, anti-codon base-pairs with codon, GTP is hydrolysed and EF released form tRNA, a second EF regenerates original EF to repeat process
describe the peptide bond formation and translocation during translation
peptidyl transferase catalyses peptide bind formation between amino acids in P and A sites, EF-2 moves ribosome along the mRNA by one triplet, empty tRNA moves from P to E site(exits and reloads with amino acid), tRNA at A site moves to P, A site free for next aminoacyl-tRNA
describe the process of termination of tranlastion
occurs when stop codon moves into A site, no aminoacyl-tRNA will base-pair with stop codon, release factor(RF) binds to stop codon, finished protein cleaved off tRNA, components dissociate form each other
