Grade 8 Protien Synthesis

1. PROTEIN SYNTHESIS
CELLS DO MORE THAN JUST COPY THEMSELVES. THEY
MANUFACTURE PROTEINS AND REPLACE ORGANELLES.
THERE ARE TWO PROCESSES INVOLVED HERE; TRANSCRIPTION
AND TRANSLATION.

2. TRANSCRIPTION – MEANS “TO WRITE”
• Transcription uses a different
molecule. It is called RNA
(Ribonucleic Acid).
• It is a single sugar molecule
opposed to a double sugar
molecule as in DNA.
• The instructions for protein
synthesis are written to a strand
of RNA by the DNA strand.
• This writing uses a new base
called Uracil.

3. TRANSCRIPTION CONTINUED
• There are three ways to
identify an RNA strand.
• 1. the presence on Uracil
in the coding
• 2. the smaller ribose
sugar.
• RNA is a single strand, not
a double helix.

4. THE MESSENGER
• The strand of RNA that is
formed is called the
Messenger RNA (mRNA).
• It contains the instructions for
the proteins that will be
manufactured.
• These instructions need to be
decoded.

5. TRANSLATION - THE DECODING OF
INFORMATION
• A ribosome attaches to the
strand of mRNA and begins to
read it.
• The bases are read in sets of
three. Each set of three is
called a CODON.
• Ex AUG, or TAC these are
two codons

6. CODING FOR AMINO ACIDS AND PROTEINS
• Each codon corresponds to a
specific amino acid.
• Sometimes several codons
code for the same amino acid.
• The ribosome signals smaller
RNA molecules to bring in
amino acids.
• These are called transfer
RNA’s (tRNA) They are the
“go getters”
• Amino acids are then

7. CODON TRANSLATION
• The codons can be translated to
amino acids by using the chart
to the right.
• The codon AUG is the start
codon telling the ribosome to
begin building proteins.
• Notice there are three
“STOP” codons.
• A larger chart is located here:
http://biology.kenyon.edu/course
s/biol114/Chap05/Chapter05.ht
ml