Protein Synthesis Flashcards
If hnRNP is present, you will prevent binding of _____ and _____.
SR AND splicing apparatuses.
i.e. hnRNP will be a major determining factor
What part of the tRNA interacts with mRNA?
Anticodon
Where on the tRNA is the amino acid loaded?
Acceptor stem
What part of the tRNA interacts with the synthetase enzymes?
D Loop
What part of the tRNA helps position the tRNA in the ribosome?
TwC Loop interacts with the 5s rRNA
What is unique about bacterial tRNAs?
Multimeric (2 or more tRNAs in a transcript, processed to monomeric precursors)
How are bacterial tRNAs modified?
- Cleaved by RNases at 5’ and 3’ ends
- Bases modified
- CCA added to 3’ end by tRNA nucleotidyl transferase
How are eukaryotic tRNAs modified?
- 5’ end cleaved
- Endonuclease removes intron at anti-codon loop - ATP required to ligate the nicks
- Bases modified
- CCA added to 3’ end
Prokaryotic ribosome:
___S + ____S = ____S
50S + 30S = 70S
Eukaryotic ribosome:
___S + ____S = ____S
60S + 40S = 80S
What trick can you use to remember the contents of prokaryotic vs eukaryotic ribosomal subunits?
The big ones are in eukaryotes, the small ones are in prokaryotes
Are all 3 rRNAs synthesize in one large precursor for bacterial rRNA?
Yes
What unique cleavage occurs by RNase III of the rRNA precursor in bacterial rRNA?
RNase III cleaves double stranded regions of RNA in an asymmetric manner leaving a 2 base 3’ overhang.
How does eukaryotic ribosomal RNA processing occur?
Self-splicing ribozyme function
What are the rRNAs in eukaryotic ribosomes?
28S, 5.8S, 5S, 18S
In eukaryotes, where do 28S, 18S, AND 5.8S rRNAs and ribosomal proteins self assemble into the ribosomal subunits? What protein transcribes them?
Nucleolus by Polymerase I
Where is 5S rRNA made and with what protein is it transcribed with?
Nucleus by Polymerase III
Where are the 2 subunits assembled into ribosomes?
Cytoplasm
The genetic code is _______, not ______, and almost ______.
Degenerate
Not ambiguous
Universal
What is a silent mutation?
A change that specifies the same amino acid
What is a nonsense mutation?
A mutation that produces a stop codon
What are the stipulations of “wobble”?
Base pairing between codon/anticodon in first and middle positions must be perfect
Somer flexibility in the 3rd (3’) position acceptable
What is a missense mutation?
A change that specifies a different amino acid
