Download Protein synthesis

Protein synthesis
Narrator
When Watson and Crick cracked the structure of DNA they had a problem – they knew that
DNA was responsible for making many different types of proteins, but how? They knew it
had to be the bases found in DNA that held the code to make proteins. Let’s call our bases
found in DNA A, T, C and G. Here is a DNA molecule – this part is unzipped and we can see
a line of bases.
Stage directions: Six or nine students line up along one ‘unzipped’ section of the rope representing DNA.
Narrator
This is part of the genetic code for making a new protein but the gene can’t leave the nucleus.
How can we get the information to the ribosome where the protein will be made?
Narrator
We need messenger RNA to help us! This smaller molecule can fit through the pores on the
nuclear membrane and transfer the genetic code to the ribosome. Let’s see how mRNA is
made.
Look at the code. The T of the DNA matches up with an A of messenger RNA, C matches
with G, G matches with C. And where we have an A this now matches with U. U is special,
it’s not in DNA, it’s in RNA.
Stage directions: Six, or nine, other mRNA students line up face to face with those representing DNA.
DNA base Pairs with mRNA base
A
U
T
A
C
G
G
C
The mRNA students hold a length of rope of string to become the RNA molecule.
Narrator
The RNA moves out of the nucleus to one of the ribosomes in the cytoplasm. mRNA moves
out (preferably through a pore in the nuclear membrane) to the ribosome.
Here the ribosome reads the genetic code and joins amino acids together in the correct
order. It takes three bases to code for one amino acid.
Stage directions: The first three bases of the RNA are ‘read’ and an amino acid represented by a student
wearing a shaped headband with amino acid on it ‘forms’. As the next three bases are read the another
amino acid forms, linking hands with the first until a chain of amino acids, ‘a protein’, is formed. The
original mRNA students can return to the nucleus to pick up more genetic code from the DNA.
Narrator
When it is finished the ribosome releases the protein.
Stage directions: Students step away from the ribosome.
Narrator
The protein can leave the cell.
Stage directions: The students representing the protein leave the cell
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© Ian Abrahams and Martin Braund (2012) Performing Science. London: Continuum.