Lecture 11 Flashcards
What are “DNA and RNA factories” in the nucleus?
This refers to DNA replication factories and RNA transcription Factories.
basically concentrations of aggregates that complete these 2 functions in the nucleus
what do tRNA’s do?
they match amino acids to the appropriate mRNA code
describe “wobble” base pairing
the ability of a codon (usually a U) can pair in a sloppy fashion during tRNA translation in order to generate diversity
usually ends up being the same AA that was originally coded for.
What are many tRNA introns spliced out?
it is a quality control step in tRNA generation that ensures that the tRNA will be folded correctly
what does an aminoacyl-tRNA synthetase do?
it hydrolyzes ATP in order to couple the AA to the tRNA
what are the 2 steps of tRNA to AA coupling?
activation of the AA by linking the carboxyl group to AMP
Transfer of the carboxyl group to the hydroxyl group of the sugar at the 3’ end of the tRNA
How does aminoacyl-tRNA synthetase prevent similar AA’s from binding in the wrong order during translation?
it has a second binding site (editing pocket) that will bind to similar AA’s attempting to be wrongly translated
the editing pocket inactivates tRNA’s bound to it by decoupling the AA from AMP
True or False: the synthetase has binding sites that match the anticodon and it “reads” the nucleotides of the signature tRNA
True
Why is the formation of peptide bonds between AA’s during translation energetically favored?
the growing C terminus is activated by the covalent attachment of the tRNA
Compare and contrast the Ribosomal subunits of eukaryotes and prokaryotes
Eukaryotic: 60s and 40s
Prokaryotic: 50s and 30s
List and describe the binding sites of ribosomes
A: amino acyl tRNA
correct tRNA is “loaded” here by binding to the ribosome ; matches anticodon to mRNA
P: peptidyl-tRNA
carboxyl end of growing peptide is released and a new peptide bond is formed with the AA that was in the A site
E: exit site
large subunit moves along, shifting tRNA’s to P and E sites on the small subunit
small subunit moves 3 nucleotides along mRNA and ejects the tRNA from the E site
What are elongation factors?
proteins that speed up peptide synthesis by hydrolyzing GTP
EF-TU and EF-G are found in_______ and EF1 and EF2 are found in ______________. Both are _______-
Prokaryotes ; Eukaryotes ; elongation factors
what happens when an incorrect codon is in the P site of a ribosome?
it leads to the misreading of the A site and causes premature termination due to successive rounds of misincorporations
basically creates a peptide that is quickly degraded and prevents translation of a damaged protein
what does the small subunit of the ribosome do?
recognizes correct codon-anticodon matches.
if the wrong match is there, this interaction wont occur, and translation wont happen (checkpoint)
