BB 4 - Translation Flashcards
What is a gene?
A specific sequence of nucleotides in DNA.
What is the name of a group of three nucleotides?
A codon
What does one codon code for?
One amino acid
How many different types of amino acids are there?
20 amino acids
What does the sequence of the codons code for?
A specific sequence of amino acids in a polypeptide.
What is the starting codon?
AUG
What are the stop codons?
UAA, UAG, UGA
What happens to the mRNA in the cytoplasm?
A ribosome which was built from ribosomal RNA - rRNA) assembles around the mRNA.
What carries amino acids to the ribsome?
Specific transfer RNAs (tRNAs)
What is complementary on between the tRNA and mRNA?
The anticodon on tRNA and the codon on mRNA.
What does the sequence of bases on the mRNA determine?
The order of amino acids in the polypeptide
What determines the order of amino acids in the polypeptide?
The sequence of bases on the mRNA
What are the three key steps of translation?
- Initiation
- Elongation
- Termination
What is step 1 in translation?
Initiation
What is step 2 in translation?
Elongation
What is step 3 in translation?
Termination
What happens in step 1 of translation (initiation)?
The initiator tRNA which has the UAC codon binds to the AUG codon to start the translation, which is the ribosome units assemble at this location.
What happens in step 2 of translation (elongation)?
The next tRNA enters the ribosome, bringing a specific amino acid, where a peptide bond forms between the first and second amino acids. The ribosome moves along the mRNA, the first tRNA is released and the process repeats.
What happens in step 3 of translation (termination)?
Elongation continues until the ribosome reaches a STOP codon (UAA, UAG, UGA). Stop codons do not code for an amino acid. Instead, they recruit a release factor to disassemble the ribosome and release the polypeptide.
