1) Translation is the process by which a ribosome synthesizes a protein based on the mRNA template. 2) It occurs in three phases: initiation, elongation, and termination. 3) During elongation, tRNAs bring amino acids to the ribosome which link them together via peptide bonds to form the protein chain. 4) Translation ends when a stop codon enters the A site and triggers release of the complete protein product.

3. Nuclear
membrane
Transcription
RNA Processing
Translation
DNA
Pre-mRNA
mRNA
Ribosome
Protein
Eukaryotic
Cell

4. Ribosome moves
towards the 3’ end

5.  Three parts:
1. initiation: start codon (AUG)
2. elongation:
3. termination: stop codon (UAG, UAA, UGA)
 Let’s make a PROTEIN!!!!.

6. Start codon is AUG;
first amino acid is
always methionine,
which may be
removed after
translation.
The large subunit joins
the complex, the
charged tRNA is
now in the P site of
the large subunit.
Initiation factors are
responsible for
assembly of the
initiation complex.

8. aa2
2-tRNA
G
A U
aa1
A U G C U A C U U C G
mRNA
A
1-tRNA
U A C
anticodon
hydrogen
bonds codon

9. Elongation: the second charged tRNA enters the
A site.

10. When the first tRNA
has released its
methionine, it moves
to the E site and
dissociates from the
ribosome—can then
become charged
again.
Elongation occurs as
the steps are
repeated, assisted
by proteins called
elongation factors.

11. Large subunit catalyzes two reactions:
Breaks bond
between tRNA in
P site and its
amino acid
Peptide bond forms between
that amino acid and the amino
acid on tRNA in the A site
1
2

12. aa1 aa2
aa3
A U G C U A C U U C G
mRNA
1-tRNA 2-tRNA
U A C G
A U
A
anticodon
hydrogen
bonds codon
peptide bond
3-tRNA
G A A
Elongation

13. aa1
aa3
A U G C U A C U U C G
mRNA
1-tRNA
2-tRNA
U A C
G
aa2
A U
A
peptide bond
3-tRNA
G A A
Ribosomes move over one codon
(leaves)

14. aa4
mRNA
aa1
aa2
2-tRNA
G
A U
aa3
A U G C U A C U U C G
A
peptide bonds
3-tRNA
G A A
4-tRNA
G C U
A C U

15. aa4
mRNA
2-tRNA
G
aa1
aa2
A U
aa3
A U G C U A C U U C G
A
peptide bonds
3-tRNA
G A A
4-tRNA
G C U
A C U
(leaves)
Ribosomes move over one codon

16. aa5
5-tRNA
mRNA
aa1
aa2
aa3
aa4
G C U A C U U C G
A
peptide bonds
3-tRNA
G A A
4-tRNA
G C U
A C U
U G A

17. aa5
5-tRNA
mRNA
aa1
aa2
peptide bonds
aa4
G C U A C U U C G
A
3-tRNA
G A A
aa3
4-tRNA
G C U
A C U
U G A
Ribosomes move over one codon

18. Termination: translation ends when a
stop codon [UAA, UAG, UGA] enters
the A site.

19. Stop codon binds a
protein release
factor—allows
hydrolysis of bond
between polypeptide
chain and tRNA on
the P site.

20. aa2
aa1
A C A U G U
mRNA
U
primary
structure
of a protein
aa3
200-tRNA
aa4
Termination
U A G
aa5
C U
aa200
aa199
terminator
or stop
codon

21. Polypeptide chain: C terminus is the last
amino acid added.

22. Enzymes degrade
mRNA!
The ribosome
subunits
dissociate.

23.  The end products of protein synthesis is a
primary structure of a protein.
 A sequence of amino acid bonded together
by peptide bonds.
aa2
aa1
aa3
aa4
aa5
aa200
aa199

24.  This m-rna can again be translated
by the same or any other ribosomes
to form the multiple copies of that
protein!!!