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DNA translation and the Genetic Code

Let’s recap where we left off:

1. In every part of the body, we constantly make new cells (replication.) During this process, cells make exact copies of their DNA.

2. DNA is an instruction to make protein. And it is kept safe as an “original”. It’s never used directly.

3. So the cell makes a copy of the gene: memory RNA (mRNA), in a process called transcription.

4.  mRNA moves out of the nucleus, into the cytoplasm, where it hooks up to a ribosome. Here it is translated into a protein.

{ http://genius.com/2617121/Biology-genius-the-central-dogma/Dna-replication-dna-to-dna-transcription-dna-to-rna-and-translation-rna-to-protein }


Protein synthesis

Lab – Protein Synthesis Manipulative Kit

Here’s our hands on lab:
Protein Synthesis Manipulative Kit

A teacher’s guide to this lab:


DNA translation

Sending the RNA copy to a ribosome, and using it to build a protein.

The Universal Genetic Code is the instruction manual that all cells use to read the DNA sequence of a gene, and build a corresponding protein.

Proteins are made of amino acids that are strung together in a chain.

Each 3-letter DNA sequence, or codon, encodes a specific amino acid.

The code has several key features:

* All protein-coding regions begin with the “start” codon, ATG.

* There are three “stop” codons that mark the end of the protein-coding region.

* Multiple codons can code for the same amino acid.

{ http://learn.genetics.utah.edu/content/molecules/dnacodes/ }


The cell reads nucleotides three at a time.

Where do we get all these amino acids from to begin with?

From the protein in our food!
food -> mouth -> esophagus -> stomach -> intestines ->
-> absorbed into bloodstream -> travels to every cell in the body ->
-> cell absorbs amino acids


Codons (group of three nucleotides) interpreted as an amino acid.

{ http://en.wikipedia.org/wiki/Transfer_RNA }


This process is mind-bogglingly fast! Here is a video showing the speed at which this takes place:

Now this amino acid chain folds up into a three-dimensional (3D) shape

Why make proteins? What does the body use them for?

DNA Every type of Protein

{ http://www.clearbiology.com/biochemistry-review-activity/proteins/ }


The shape of the protein turns into a machine! The shape defines it’s function.

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