Transcription and Translation

Protein synthesis is very important for any living thing! Why???

-Proteins make up antibodies, which fight diseases

-Proteins make up your CELL STRUCTURE..so without proteins, you'd have no cells

-Proteins make up your muscles..without them you couldnt move. (Some people have disorderse where their protein synthesis doesn't work properly, and they have degenerative muscular disorders because of this--- example=alzheimers)

Where do you get proteins from??? -Meat, beans, a combination of vegetables, chickpeas, tofu, etc...


The steps of protein synthesis: 
1. DNA strand divides in 2
2. Transcription
3. Translation


Here is a diagram of what happens in protein synthesis overall.....

Now let me take you on a tour of protein synthesis.

1. The DNA divides in 2: remember that for protein synthesis to occur, the information from DNA is needed to make the proteins. By information, I mean the sequences (or order) of the bases. So... having a DNA strand with bases ATCGGGC would lead to a different protein than the bases TACGGCG. Even though the same bases are present, the sequences is different, so the protein is different.

..To get the information from DNA for our proteins, the strands need to be separated so only 1 strand at a time is read.

2. Transcription: This happens in the nucleus. Information from DNA is used to make an mRNA strand. mRNA stands for MESSENGER RNA..this is the messenger in the protein synthesis process. Remember that the bases in DNA are A,T,C,G and in RNA are A,U,C,G. A pairs with U (and vice versa), C pairs with G (and vice versa).

If I were to ask you to TRANSCRIBE the following DNA strand to an mRNA strand

ATCGGCATC

It would become...

UAGCCGUAG.

(Because A in DNA codes for U in RNA, then T in DNA codes for A in RNA, then C in DNA codes for G in RNA, then G in DNA codes for C in RNA, etc.)

3. The last step in making our protein is called TRANSLATION. In translation, the information in mRNA is used to make a protein.

First, the mRNA needs to leave the nucleus and attach to a ribosome (which is found in the cytoplasm)..take a look back up at the diagram to understand where in the cell we are right now.

Next, the mRNA is broken up into groups of 3 called CODONS. 

Let's go back to our mRNA strand: TACCCGUAG

The codons would be:  AUG CCG UAG

Remember that a protein is really just a long chain of AMINO ACIDS.

Here is an image of a protein (note that each ball represents 1 amino acid). 

Now that we have our codons, how do we figure out which amino acid strands they code for? 

Using this chart!

Our codons are AUG CCG UAG

Find AUG on the chart! You will see that it codes for Met.

CCG codes for Pro

UAG codes for Stop.

If you were to write the chain of amino acids, it would look like this:

Met-Pro-Stop

You have now made your protein.

Take a look at the following Protein Synthesis video:

http://www.youtube.com/watch?v=NJxobgkPEAo

And play the following game on Protein Synthesis 

http://learn.genetics.utah.edu/content/begin/dna/transcribe/