Protein SynthesisPart II:

Translation

• Using the length of messenger RNA to assemble amino acids into proteins.

• Takes place in a ribosome.

Step 1:-mRNA is attached to a ribosome

ribosome

Step 2:-The ribosome “reads” the mRNA three bases at a time.-These three bases are called the mRNA codon.

mRNA “codons”

ribosome

Step 3:-The ribosome guides a different type of RNA to each codon.-This type of RNA is called transfer RNA (tRNA).

mRNA “codons”

c A

tRNA

valine

c A

tRNA

valine

Transfer RNA (tRNA)

• Made of RNA

• Attached to a specific amino acid

• Contains an anti-codon of three bases

• tRNA’s anticodon will pair-up with RNA’s codon.

Anti-codon

Amino acid

Reading a round genetic code:

For the first codon (G U A):1. Find “G” in the middle of the wheel.2. Follow that to “U” in the next outer

ring.3. Follow that to the A in the third ring.4. Read the name of the amino acid in

the last ring.5. In this case G U A codes for Valine.

Reading a table genetic code:

For the first codon (G U A):1. Find “G” on the left hand side.2. Match the “G” with the “U” from

the top.3. Follow that to the A in the third

ring.4. Match both of these letters with

the right hand side.5. In this case G U A codes for

Valine.

Step 4:-The ribosome guides another tRNA to the mRNA codon.

mRNA “codons”

c A

tRNA

valine

G A

tRNA

Leucine

Step 5:-The ribosome bonds the two amino acids together.

mRNA “codons”

c A

tRNA

valine

G A

tRNA

Leucine

Step 6:-The first tRNA releases from the mRNA and its amino acid.

mRNA “codons”

c A

tRNA

valine

G A

tRNA

Leucine

Step 7:-The ribosome moves to the next codon.

mRNA “codons”

valine

G A

tRNA

Leucine

Step 8:-The ribosome guides another tRNA to the mRNA codon.

mRNA “codons”

valine

G A

tRNA

Leucine

cA

tRNA

A

valine

Step 9:-The ribosome bonds the amino acids together.

mRNA “codons”

valine

G A

tRNA

Leucine

cA

tRNA

A

valine

Step 10:-A tRNA releases from the mRNA and its amino acid.

mRNA “codons”

valine Leucine

cA

tRNA

A

valine

G A

tRNA

U

Step 11:-The ribosome moves to the next codon.

mRNA “codons”

valine Leucine

cA

tRNA

A

valine

Step 12:-The ribosome guides another tRNA to the mRNA codon.

mRNA “codons”

valine Leucine

cA

tRNA

A

valine

G

tRNA

Step 13:-The ribosome bonds the amino acids together.

mRNA “codons”

valine Leucine

cA

tRNA

A

valine

GlutamicAcid

G A G

tRNA

Step 14:-The tRNA molecules detach from the mRNA and their amino acids.

mRNA “codons”

valine Leucine

cA

tRNA

A

valine

GlutamicAcid

G A G

tRNA

Step 15:-The protein is now complete.

mRNA “codons”

valine Leucinevaline

GlutamicAcid