L 19 Flashcards
(24 cards)
What do they mean by synonyms for the genetic code?
It means that there are codons that specify the same amino acid.
What are the three stop codons?
UAA, UAG, UG
What is the start codon
AUG, GUG
what do you need in order to translate RNA bases to a polypeptide?
you need tRNA
What do tRNA synthetases do?
attach amino acids to tRNAs
What 2d structure does a tRNA tend to have
cloverleaf
describe the arms of the clover
- amino acid arm, stem acceptor
- D arm - contains two or three D residues at dif positions
D being dihydrouridine modified base - Wobble position - the 5p loop with anticodon
- T arm with pseudouridine
MEMO DATA
How far away is the AA aceptor arm away from the anticodon?
76 A
Why do tRNAs ahve a complex tertiary struc?
extensive stacking interactions
non watson crick base pairing within and bet loops
tertiary H bonds involve invariant bases
H bonding within and bet helical stems.
What are three sources of error in translation
- aaRS uses wrong amino acid as substrate
- aaRS selects wrong tRNA as substrate
- Ribosome selects wrong aa-tRNA for codon
how does aminoacyl-tRNA Synthetasses select the correct amino acid?
ATP and time used to increase accuracy
3’ terminus has IleRS dinucleotide fold
What is the direction of the anticodon sequence?
5’ to 3’
What is the meaning of the anticodon wobble?
Since codons are degenerate, the third position of the codon may vary.
Many tRNAs have 2 or 3 codons specify their cognate amino acids.
Third anticodon position is commonly known as what?
modified base
What promotes the wobble hypothesis?
inosine
What exactly is inosine?
deaminated adenosine
What kind of structures does ribosomes have?
large and small subunits (rRNA) and a number of small proteins
How complex is the ribosome structure, and is it conserved?
Complex and conserved
How are codons read when ribosomes binds with mRNA?
codons are read with high fidelity
Ribosomes have spec binding sites for which RNA molecule?
tRNA
Ribosomes mediate the interaction of non ribosomal proteins that promotes what?
Promotes poly peptide synthesis initiation elongation termination
Ribosomes catalyze what kind of bond formation?
Peptide bond formation
How does the prokaryotic and eukaryotic structures compare?
They are both similar and have conserved function
What are 3 states in protein translation
- intiation- ribosome placed on start codon
- elongation - mRNA templated polypeptide poymerization
- Termination- polypeptide and mRNA are released
