Download Steps of Translation - Madison Public Schools

Steps of Translation
Honors Biology
Monkemeier
Tuesday, May 23, 2017
Initiation
 Large subunit and small subunit of the
ribosomes come together.
 When the subunits come together they
form a “stage” with 2-3 “seats”
 mRNA threads itself in between the large
and small subunits.
 A tRNA carrying Methionine checks its
anticodon to the codon on the mRNA. The
anticodon and codon are complementary to
each other.
Initiation – What is not shown?
Initiation Complete
Elongation
 Another tRNA carrying an amino acid matches its
anticodon complementary to the codon on the mRNA.
 A peptide bond is formed between methionine and the
new amino acid.
 The Ribosome moves over one codon on the mRNA.
 The original tRNA carrying methionine goes away.
 Another tRNA carrying an amino acid comes in and
matches its anticodon complementary to the codon on
the mRNA (newly exposed)
 A peptide bond forms between the two amino acids.
 The ribosome moves over one codon
 PROCESS CONTINUES
Elongation
Termination
 A stop codon appears in the “A” site
on the ribosome.
 tRNA carrying the polypeptide falls
off.
 The large and small subunits of the
ribosome break apart.
 A newly formed polypeptide strand is
formed.
Protein Formation
 Remember that there are four levels of
protein structure.
 Translation forms the first level of protein
structure – the polypeptide chain
 Secondary structure involves hydrogen
boding of the chain to form alpha helix or
beta pleated sheet
 Tertiary structure includes more bonding
between the chain – Ex: Sulfur bridges
 Quarternary structure: several chains
together.