Section 8.5:
Translation
 Translation:
The
process of
converting mRNA
into proteins.
 Takes place on a
ribosome in the
cytoplasm.
The cytoplasm contains amino acids, tRNA, and
ribosomes, which are all needed for protein synthesis.
Q: What language does mRNA “speak?”
A: mRNA speaks in “codon”
Codon: A combination of 3 mRNA
nucleotides.
Every codon codes for a
specific amino acid.
Some code to “start”
and “stop” translation.
We use a Codon Chart
to translate.
Codon Chart
Start and
Methionine
You will be given a
Codon Chart…Glue
this into your
notebook!
tRNA

tRNA’s job = grab a free amino acid from
the cytoplasm and take it to the mRNA in
the ribosome to build a protein.
Q: How does tRNA know where to
take its amino acid?
A: tRNA has an anti-codon
that lets it find its spot on
the mRNA strand.
 Anti-codon: A region of
tRNA consisting of 3
bases complementary to
the mRNA codon
(A with U, G with C)

This part shows mRNA coming
out of a nuclear pore after
transcription.
his part shows mRNA
onnected to two ribosomes.
his part shows tRNA picking up a free amino
cid, then bringing it to the mRNA & ribosome.
his part shows all of
he amino acids that
ave been “dropped
ff” by tRNAs and are
ow forming a protein
also known as a
olypeptide chain).
Steps of Translation:
 Step
1: The start
codon (AUG) is
recognized by a
tRNA anticodon.
 Step 2: A tRNA
anticodon binds to
an mRNA codon
and brings an
amino acid with it.
 Step
3: tRNA anticodons keep binding to
mRNA codons, forming a chain of amino
acids to build a protein.
 Step 4: This process ends when a stop
codon is reached.

Stop Codons: UAA, UAG, UGA
Now we’ll watch the last 2
minutes of this clip:
http://www.youtube.com/watch?v=41
_Ne5mS2ls&feature=related

The finished chain of amino acids form a protein!
Final Result = chain of amino acids = Protein!
Proteins each have a
different amino acid
sequence.
 They can be anywhere
from 50 to 30000
amino acids long.
 They can be altered by
DNA mutations.

Summary



Place stars next to the most important concepts
or information in your notes.
Create a short summary of the three most
important concepts.
Share your stars and summaries with your elbow
partner.