Name:
Period:
A Secret Code
Activity
DNA is the molecule that stores the genetic information of every living thing
on Earth. This information controls the normal functioning of cells. Stored
within the nucleotide sequence of a DNA molecule are the instructions for
building proteins. As you learned earlier this year, proteins are incredibly
diverse macromolecules, and they perform a variety of functions including
enzymes, as the structural components of cells, as channels for transport, as
cellular communicators, and as motility organs. Ultimately, living things are
what their proteins allow them to be, and the DNA they inherit determines
the proteins they can make. In the following activities you will simulate the
way the instructions encoded in DNA is decoded by the cell’s protein-building
machinery.
Instructions:
To use this ring, think of the inner disk as the true message and the outer disk as the encoded
message. The numbers in the square window of the inner disk represent the code shift of your
message. If you set 1 in the window, there is a shift of 1, and "A"="B", "B"="C" and so on.
Let's decode XPDDLRP. We have no idea what it says, but if we know the code number is 11, we
can set that in the window. We decipher code from the outer ring to the inner. Across from "X"
is "M", across from "P" is "E", "D"="S", "D"="S" again, "L"="A", "R"="G", and "P"="E". So
XPDDLRP decoded with a shift of 11 is MESSAGE.
1. Set the shift as number as 20 – move the ring until the number 20 appears in the square
window. Leave it here to decode the following message –
GYYN IH
_____ __
NBY
___
JCYL UN
____ __
GCXHCABN
__________
Now let’s simulate the effects of a mutation. Mutations are permanent changes in the DNA that
affect the message. In living organisms, this will change the protein that is produced by that
strand of DNA. In this activity, we will see how the message is changed by the change, addition
or deletion of letters.
2. Keep the decoder ring set on ‘20’. Decode the new message (the first letter of the last word
has mutated). Note how the meaning of the message has changed.
GYUN
IH
NBY
JCYL
UN
GCXHCABN
Name:
Period:
_____ __
___
____
__
__________
3. Keep the decoder ring set on ‘20’. Decode the new message (one letter has been inserted at
the end of the third word). Note how the meaning of the message has changed.
GYYN
_____
IH NBK YJCY
___ ____ ______
LU NGCXHCABN
___ _____________
Remember that the purpose of this activity is to simulate the way that the code in the DNA of
living things is decoded into something meaningful. Although this is just a metaphor, the
elements of this activity represent actual structures in cells.
DNA is the coded message. The decoded message is the protein produced by the cell.
The cipher ring is a ribosome – it is used to decode messages in the DNA and use the
instructions to build a protein.