Expert: Florence M Rollwagen - 6/17/2008

Question
QUESTION: This is my problem:

Write the formula which shows the sequence of events that results in the production of a new protein molecule. Then, explain what is happening in each step of the sequence.

Thank you so much for your help!

ANSWER: Hi Allison:  Thanks for your question.  It would help me to answer you if you told me what grade you were in, what is this course, and how detailed an explanation you're expecting.

Protein synthesis is a complicated matter, studied in more and more detail as a student advances through school/college.

If you're thinking of DNA to RNA to protein, there are a number of steps and structures that are involved.

Just get back to me with the grade you are in and I'll send you an answer.

In the meanwhile, just try this website:
http://www.lewport.wnyric.org/jwanamaker/animations/protein%20synthesis%20-%20lo


FMR

---------- FOLLOW-UP ----------

QUESTION: I'm in the 11th grade. But, I'm homeschooled, so grades don't really matter in the program I am at.

I am referring to the DNA -> RNA -> protein formula. All I know so far (after searching the internet) is that from DNA to RNA, that is transcription, and from RNA to a proteing is translation. But, I don't know what they mean.

Thank you for helping me out!

Answer
Hi Allison:  Thanks for the follow-up.

The structure of DNA is a double helix.  That means it looks like a twisted ladder, with deoxyribose (a 5 carbon sugar), a phosphate group (PO3) on the outside.  The rungs of the ladder are the nucleotide bases and there are four of them.  Adenine, thymine, cytosine and guanine.  The nucleotide base pairing rules come from the shapes of these 4 nucleotides so they fit together only one way.  Adenine bonds with thymine, cytosine with guanine.  The sequence (order) of these four bases is what gives the genetic code its unique characteristics.  Each set of three nucleotides is called a codon.  Each codon codes for one amino acid.  

The first step is transcription.  In this process the DNA is read by RNA polymerase (an enzyme) and makes messenger RNA (mRNA).  The mRNA follows the base-pairing rules and makes a mirror image of the DNA.  So if the DNA reads TACCGAAT (I just made that up, it doesn't code for anything), the RNA will be AUGGCUUA.  If you just match up the letters you'll see that T pairs with A, A pairs with U [RNA uses uracil (U) instead of thymine (T)], C pairs with G, etc.   So now we have a transcribed mRNA sequence in which the information came from the DNA sequence of nucleic acids.

Now the mRNA goes out of the nucleus (where the DNA is) and enters the cytoplasm.  This is where the 3 codon rules come into effect.  Each set of three nucleic acids codes for a specific amino acid.  This process is called translation.  The mRNA is read by the ribosome (rRNA) and transfer RNA (tRNA) to synthesize a protein.  If you go to this website you can play a little transcription and translation game:

http://learn.genetics.utah.edu/units/basics/transcribe/

I use this game with my students in class and they seem to enjoy it.

Just think of the sentence "thecatatetherat" and you will see how the 3 nucleotides can make a "sentence" of proteins.

If you want to learn more, you can go to the following website for movies of these processes.  I use this website a lot with my students.  It's very informative.

http://vcell.ndsu.edu/animations/

I hope this answer has helped you.  Please write back if you have more questions.
FM Rollwagen, PhD