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# Summary

### The Genetic Code

So we've talked about how our genes contribute to our phenotype. But what exactly are genes? Genes, as we've mentioned, are made up of DNA and provide the information for our cells to carry out important biological processes that ultimately lead to phenotype. Those processes depend on molecules called proteins. The DNA provides instructions for building proteins, which are made up of essential building blocks called amino acids.

Almost all proteins are made up of combinations and permutations of the same 20 amino acids. This is where the code of DNA comes in. DNA is composed of 4 different molecules called nucleotides or bases: adenosine, thymine, cytosine, and guanine. We abbreviate these as A, T, C, and G, respectively.

An important question is immediately apparent: how many ways can 4 base pairs code 20 unique amino acids? The answer is in combinations. Let's do some quick math to figure out how many letters in a row you need to code for 20 amino acids.

But wait - we know there are 20 amino acids! A 1-letter code only created 4 amino acids and a 2-letter code only created 16 amino acids. Can you determine how many letters are necessary to create all 20 amino acids?

Note that in Python, we use "**" as an exponent symbol (i.e. to calculate 3 to the 8th power [3^8], we would type 3**8).

1 print('A 1-letter code:', #Your code here)

print('A 2-letter code:', #Your code here)

print('A 3-letter code:', #Your code here)

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