Translation (Lecture 12) Flashcards
Translation
Monocistronic mRNA
Initiation in eukaryotes occurs at which side?
What is the start codon?
Initiation in eukaryotes is at the 5’ cap, and the first AUG is the start codon
To translate the RNA transcript we need what three things?
To translate the RNA transcript we need:
1. A sequence for the Ribosome to initiate translation (it doesn’t just begin at the 5’ end)
- A genetic code that will specify which amino acid will be incorporated
- A termination sequence so the Ribosome knows when to stop
What is the start codon?
What are the three stop codons?
Translation begins at AUG and terminates at UAA or UAG or UGA
The AUG sets the code, so the next 3 nucleotides after AUG will code for another amino, and so on.
Properties of the Genetic Code
- There are no ______ between codons
- Codons are…
There are no spaces between codons
- codons are adjacent
Properties of the Genetic Code
- The genetic code is…
- each nucleotide is part of _______
- The genetic code is non-overlapping
- each nucleotide is part of one codon
Properties of the Genetic Code
- The genetic code is…
- most amino acids are specified by more than ________
Properties of the Genetic Code
- The genetic code is degenerate
- most amino acids are specified by more than one codon
Properties of the Genetic Code
- The genetic code is…
- Amino acids with similar properties are specified by related codons
- The genetic code is (nearly)…
- With minor exceptions, each triplet/codon has the same meaning in _________
- The genetic code is ordered
- Amino acids with similar properties are specified by related codons
- The genetic code is (nearly)…
- With minor exceptions, each triplet/codon has the same meaning in all organisms
The genetic code
What does AUG code for?
AUG codes for Met: start codon. Note that unlike most of the other amino acids, Met is only coded for by AUG.
What are the three components for Translation?
- Messanger RNA (mRNA)
- Transfer RNA (tRNA)
- Ribosome (ribosomal RNA + ribosomal proteins)
Ribosomes
The large subunit includes 3 binding sites for tRNAs what are the 3 sites?
- Exit Site (E)
- Peptidyl Site (P)
- Aminoacyl Site (A)
tRNA
Where does the amino acid attachment site bind?
The amino acid attachment site binds to the 3’ end
Charging of Transfer RNAs with the Matching Amino acid
Enzymes known as aminoacyl tRNA synthetases are important in translation, what is their purpose?
Enzymes known as aminoacyl tRNA synthetases are important in translation. They carry out the actual translation from nucleic acid to amino acid
The first base in the codon 5’ end pairs with…
Every protein begins with what amino acid?
Note that the first base in the codon (5’ end) pairs with the last base (3’ end) in the anticodon.
Translation always begins with the AUG codon, which codes for Met. Therefore, every protein begins with the Met amino acid.
Translation Elongation
Translation of the sequence of codons in messenger RNA into the sequence of amino acids in a ______________ is an orderly process repeated over and over again
Translation of the sequence of codons in messenger RNA into the sequence of amino acids in a polypeptide chain is an orderly process repeated over and over again
What happens in the first stage of initiation?
A reaction transfers the Met to the amino acid on the tRNA in the A site forming a peptide bond.