| Orientation:
|
| This activity is designed to help
students understand how the genetic code works for amino
acids. Please answer the following questions in your
activity journal page. |
| Supplies: |
|
Access
the Student Journal for Activity 1
|
Activity
1 - Information Coding
This activity is designed to help you understand how the genetic
code allows many different types of amino acids to be created.
Complete the activity on your student journal sheet.
1. Calculate the following:
a. How many amino acids could be coded for if there were only
four nucleotides operating singly?
b. How many amino acids could be coded for if the
nucleotides occurred in the pairs shown below? That is, how
may different ways can you write a string of letters A-A, A-T,
A-C, etc.?
c. Can you state the number of possibilities by a mathematical
expression?
2. Clearly, four pairs cannot specify 20 amino acids. What
mechanism do you suppose cells have for specifying the large
number of amino acids?
If an amino acid could be specified by two nucleotide pairs,
it would not be possible to specify 20 amino acids. But suppose
it took a sequence of THREE nucleotides to specify any given
amino acid. Then, the total possibilities, 43 = 64,
is more than enough to code for 20 amino acids. Clever
experiments some 35 years ago revealed that this is the coding
scheme used by cells. The complete code for amino acids seems to
be as shown in activity 2.
|
