Chapter 4 Lecture 3 - Protein synthesis, steps of translation Flashcards
1
Q
What do ribosomes consist of
A
2 rRNA subunits, large and small subunit
2
Q
How many binding sites do ribosomes have
A
3
3
Q
What are the three binding sites of ribosomes
A
A, P, and E
4
Q
What is the shape of tRNA
A
like an L
5
Q
Where is the anticodon on tRNA
A
in a loop on one side
6
Q
What is the function of the side not containing the anticodon on tRNA
A
Bind to amino acids
7
Q
What are the 3 main stages of translation
A
Initiation, elongation, termination
8
Q
What does mRNA do once it leaves the nucleus
A
It forms a loop
9
Q
Steps of initiation
A
- Small ribosomal subunit that has initiatior tRNA attached binds to mRNA on the 5’ end and moves toward the 3’ end searching for the start codon
- Initiation factors dissociate and the large subunit binds
- tRNAs come in to begin polypeptide synthesis
10
Q
What is the anticodon and the amino acid of the initiatior tRNA
A
UAC, Methionine
11
Q
What is the start site of mRNA
A
AUG
12
Q
Steps to elongation
A
- For a new amino acid, tRNA enters the A site by base pairing (anticodon matches codon of mRNA)
- Amino acid attached to tRNA in A site links to amino acid attached to tRNA in P site
- Large subunit shifts forward, and the used tRNA moves to the E site, while the remaining tRNA moves to the P site
- Small subunit shifts and the used tRNA is ejected from the ribosome
- Cycle repeated
13
Q
Steps to termination
A
- End is signaled by presence of a stop codon
- Release factor binds
- Release factor causes ribosomes and mRNA to dissociate but they can reassemble to create new protein
14
Q
What are the three stop codons?
A
UAA, UAG, UGA
15
Q
What type of molecule is the release factor
A
Protein
