Protein Synthesis Activity
Background information:
DNA has 4 nucleotide bases:
Adenine and Thymine pair up
Guanine and Cytosine pair up
RNA has the same bases with the exception that Uracil is present instead of Thymine. Uracil
bonds with Adenine.
1. Colour your DNA strand so that the bases are different colours but all of the bases of the same
type are the same colour.
2. Cut out the DNA and mRNA molecules. (mRNA is messenger RNA)
TRANSCRIPTION: occurs in the nucleus
3. Create the nucleus on the left side of your desk by placing your DNA strand there. Unzip the
DNA molecule by cutting on the dotted line. Discard the bottom strand of DNA (this would not
be discarded in a “real” cell but we are simplifying the process).
4. Line up the mRNA strand to your DNA strand so that the “rungs” on the ladders match up. Fill in
the appropriate complimentary bases on the mRNA based upon the DNA. Colour them using the
same colour scheme you made for your DNA (use the same colour for U as you did for T) ( If
the DNA strand has an A, the mRNA at that spot will have a U…and so on). See picture below:
TRANSLATION: occurs in the cytoplasm
5. The right side of your desk is the “cytoplasm”. Move the mRNA to the cytoplasm. Cut out the
ribosome. Place it in the cytoplasm.
6. Place the left end of the mRNA on the ribosome as shown in the picture.
7. Cut out the 5 tRNA (transfer RNA) molecules. tRNA are found in the cytoplasm. On one side
they have 3 nucleotide bases (called the anticodon). On their other side they have a receptor
site for a particular amino acid. (For example the CAA anticodon codes for Valine only.) This
tRNA would never pick up a different amino acid than the one it is coded for. tRNA’s job is to
find amino acids that are floating in the cytosol and bring them to the mRNA now attached to the
ribosome. The ribosome and mRNA has room for 2 tRNA at a time.
8. The ribosome “reads” the first 3 codons. It “calls for” a tRNA with the complimentary anticodon.
The tRNA attaches itself to the mRNA. Place the complimentary tRNA anticodon on your mRNA.
9. Keep the tRNA attached to the mRNA and move the mRNA to the left 3 bases. Find tRNA for the
second codon. Attach it.
10. Cut the amino acid off the first tRNA and tape the amino acid to the second amino acid. This
tape represents a peptide bond. Throw the first tRNA into the cytoplasm. This tRNA will now
find another amino acid to bond to.
11. Continue with translation until you have made a polypeptide made of five amino acids. What
order are they in?