13.2 Flashcards
RNA contains four different bases:
adenine, cytosine
uracil and guanine.
These bases form language in just four letters:
A, U, C, G.
(1 amino acid=
3 bases)
The genetic code is read in three-letter groupings called
Codons
A codon
is a group of three nucleotide bases in
messenger RNA that specifies a particular amino acid.
Different codons can specify
the same amino acid.
the start codon for
protein synthesis.
The methionine codon AUG
How many stop codons are there
3
AAA
LYS
CUA
Leu
Ribosomes use the sequence of codons in mRNA to
Ribosomes use the sequence of codons in mRNA to
assemble amino acids into polypeptide chains.
The decoding of an mRNA message into a protein is a
process known as
Translation
The translation process steps
Translation starts when a ribosome attaches to an mRNA
molecule.
2
As each codon passes through the ribosome, tRNA’s
bring the proper amino acids into the ribosome.
3
Once a time, the ribosome then attaches these amino
acids to the growing chain.
The polypeptide chain continues to grow till it reaches a
“stop” codon on the mRNA molecule.
5
Then it releases the formed polypeptide and the mRNA
completing the translation process.
Each tRNA molecule carries just
One kind of amino acid
in addition each tRNA molecule has three unpaired bases
called the
Anticodon
