Protein Synthesis
Review!

What are some functions of proteins?
Enzymes, which speed up chemical reactions
 Build and repair cell structures
 Determine the structure & function of living
organisms

Review!
Proteins are polymers, made up of
monomers called amino acids
 There are 20 different types of amino acids

Review!
What codes for these proteins?
 DNA contains the sequence of nucleotides
that codes for the synthesis of proteins.
 Problem:

DNA is found in the nucleus.
 Proteins are made at the ribosomes, which
are found in the cytoplasm


HOW CAN THE INFORMATION FROM
THE NUCLEUS GET TO THE
RIBOSOME?
RNA! – mRNA is used to move information
from the DNA to ribosomes
 This process is called TRANSCRIPTION.

Translation


The process of
converting the
information in the
nitrogen base
sequence of
mRNA into a
sequence of amino
acids which make
up proteins
Occurs in the
RIBOSOMES
Translation



1. mRNA attaches
and passes through
the ribosome.
2. First codon on
mRNA moves into
position.
3. tRNA (transfer
RNA) starts to bring
amino acids to the
ribosome.
Translation
4. tRNA
ANTICODON
matches up to
mRNA codon.
 5. mRNA slides
through the
ribosome to next
mRNA codon.

Translation

6. New tRNA
anticodon matches
to next mRNA
codon.

7. Amino acids on
two tRNAs form a
peptide bond with
one another. First
tRNA floats away to
pick up another
amino acid for later
use
Translation

8. Process continues
until a stop codon on
the mRNA is reached.
9. Result = an amino
acid chain is created
*Chain of amino acids =
polypeptide chain =
PROTEIN (more than
one polypeptide chain)


Protein Synthesis
Animation
Let’s Review…again!
Decode the following
If the coding DNA strand contained the
following sequence: TAC CGA TTG ACT
 What would the mRNA strand be?
AUG GCU AAC UGA
 What would the tRNA sequence be?
UAC CGA UUG ACU
 What would the amino acid sequence be?
(base it on the mRNA strand!)
methionine, alanine, asparagine, “stop”
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