translation- lqc 5b Flashcards
Where in the cell does translation take place?
On ribosomes in cytoplasm
step 1 of the process of translation
mRNA leaves the nucleus and a ribosome attaches to it at a start codon
step 2 of the process of translation
Each tRNA attaches to a specific amino acid and carries it to the ribosome
step 3 of the process of translation
Complementary base pairing takes place between the anticodon on tRNA and the codon on mRNA
step 4 of the process of translation
A peptide bond forms between amino acids in a condensation reaction
step 5 of the process of translation
The ribosome moves along mRNA and detaches from mRNA at a stop codon
step 6 of the process of translation
The completed polypeptide chain detaches from the ribosome
role of ribosome in transcription
Site of translation, attaches to mRNA and moves along mRNA translating codons – has sites for two tRNA molecules. Amino acids joined together here
role of mRNA in transcription
3 bases on mRNA which code for one specific amino acid – codon binds to a specific complementary tRNA anticodon, so sequence of codons determines sequence of amino acids in polypeptide chain
role of tRNA in transcription
Each tRNA attaches to and carries ONE specific amino acid to the ribosome – has an anticodon (3 bases) which binds to a specific codon on mRNA. Can be continually reused
role of start codon in transcription
Occurs at the start of the gene and is recognised by the ribosome as the place to bind to the mRNA, so signals the start of the polypeptide chain (start of translation)
role of stop codon in transcription
Occurs at the end of the gene and is recognised by the ribosome as the place to detach from the mRNA, so signals the end of the polypeptide chain
triplet code
three bases code for one amino acid
degenerate
more than one triplet code can code for the same (one) amino acid
non-overlapping
each base is only part of one triplet
