mRNA translation Flashcards
translation requires mRNA, tRNA, and __________ ____________
ribosomal subunits
stages of translation:
initiation
elongation
termination
- always 3 bases
- sense codons sequentially read
- translation start and stop
codons
stop codons= _________ ___________
start codons defines the _________ _
frame shift mutation(mutation that alters the reading frame)
nonsense codons
reading frame
tRNA are ___________
translators
tRNA composed of ___________ and _________ ________
anticodon and amino acid
genetic code is ______________
- 64 possible codons
- ____ amino acids
- multiple codons code for same aa
degenerate
20
synonymous codons
-GGU, GGC, GGA, GGG all code for glycine
“__________” at third position in codon
wobble
the third codon/anticodon position
-isoaccepter tRNAs (different codon, same amino acid)
wobble rule
ribosomes are the catalysts of
translation
composed of __ major subunits
- each subunit composed of numerous proteins
- also composed of ______, ________
2
RNA, rRNA
in eukaryotes: rRNA synthesized in the __________
- proteins synthesized in the __________
- assembly ribosome subunits in the nucleolus
nucleus
cytosol
amino acids are added one at a time
-speed (15-20 amino acids per second in proks and 2-6 AA/sec in euks)
elongation/polypeptide synthesis
16S is on small ribosomal subunit
- decoding function: error checking and occurs at A site
- 1 mistake per 10,000 aa
error checking performed by 16S rRNA
.. occurs at the stop codon
termination
the _______ _______ is recognized by a protein (release factor)
stop codon
translation can begin before ____________ ends in prok
why doesn’t this happen in euks?
transcription
proteins wouldn’t be able to get out, difficult to process mRNA
idea that a single gene controls the synthesis of one enzyme
who?
one gene/one enzyme hypothesis
beadle and tatuem 1941
amendments:
- many proteins don’t function as enzymes
- some proteins are composed of >1 polypeptide or linear seq of aa
- many genes don’t encode polypeptides
- some genes can encode several polypeptides by?
one gene/ one enzyme hypothesis
splicing
linear seq of amino acid
polypeptide
one or several polypeptides with specific biological function
protein
polypeptide chains are _____________ ___________
directionally polarized
polypeptide chains are joined by ________ _______
-first aa is at the N-terminus/ amino terminal end
peptide bonds
last aa is at the C-terminus/ carboxl terminal end
polypeptide chains are joined by peptide bonds