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OK, question for all you smart mom's - specifically in Biology..

Posted by on Jan. 25, 2010 at 9:43 PM
  • 8 Replies

I'm trying to figure out how to state the reason for all the variety in nature when our DNA has only four bases. 

I know it's very long and complicated, and I've been reading this chapter for the last hour, and what I do know is that these four bases contain the information for building proteins in our cells.. The proteins in our cells is what's responsible for making us all so unique.  And there are many steps between the four bases and protein.

I've been searching all over the web for a 'dumbed down' verison of this information and I'm just not finding it.. It's rather frustrating..  Anyway.. any advice would be lovely. 

by on Jan. 25, 2010 at 9:43 PM
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by Gold Member on Jan. 25, 2010 at 9:59 PM

sorry don't know but here's a bump 

by Corinne on Jan. 25, 2010 at 10:08 PM

Good luck and bump

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by on Jan. 25, 2010 at 10:12 PM

Are talking about the G, A, C, and...T?  It's been a long time.  I remember the movie Gattaca took it's title from the DNA letters.

Umm...Are you needing to explain the process, or the unlimited genetic combinations or what?  Who's the target audience for your presentation?

by on Jan. 25, 2010 at 10:22 PM

I am not quite sure what you are looking for. It's not necessarily the protiens that make us unique, it's the variation of our DNA code.  

"Religion is dangerous because it allows human beings, who don't have all the answers, to think they do."

~ The Dems and the Reps remind me of my kids ~
One is always pointing out the bad things that the other is doing in hopes that I don't notice all the bullshit he is trying to get away with...I'm not fooled by my own kids and I'm not fooled by Politicians.

by on Jan. 25, 2010 at 10:42 PM

I am not a science geek by any means but this is how I understand it works.  FYI: I am reaching into the very back of my brain, to retrieve this info, so please verify, with what your instructor is saying.  Again, just as I understand it,

You have the 4 bases A<C<G<T. For century's scientists disregarded DNA because they could not fathem that 4 bases could possibly be the "center" of life.  They were incorrectly assuming that ACG&T could only arrange itself in specific strings and therefore the combination had to equal a finite number of combinations. 

What scientists discovered was living organisms do not have the same percentage of each base. Meaning you don't have to have 100% of A, 100% of C, 100% of G & 100% of T.  Rather a molecule can contain- different %'s of each base. So for example 30%A, 30%C, 30% G & 10% T or 30%A, 35%C, 25% G& 10%T. 

Now that certainly increased the the number of combinations but although much larger it is still a finite number.  What they next discovered was that bacteria & viruses could actually exchange DNA and basically "inject" itself into the DNA strain, causing the bacteria to change the cell traits, multiply (diseases, cancers, etc).  With that knowledge your combination possiblities becomes extremely large. However, one more addition..... 

The next big discovery was that DNA is a helix (ladder shape); one base can form the sides and then certain combinations can form the rungs.  (The bases are very particular about who they will pair with )but again it adds more possible combinations to total package.  All the above give us the variety of DNA possibilites we have today.

Is that what you were looking for?

by on Jan. 25, 2010 at 11:19 PM

Okay...You are asking the right mama lol. 

The 4 nucleotides are Adenine, Guanine, Cytosine and Thymine.
Groups 3 of these are called codons. (Example, ACG would be one codon).
Once your DNA is replicated, you can then start protein synthesis.

The DNA is what specifies which protein will be made.

The first part is Transcription.  Transcription occurs in the nucleus of a cell and is the copying of a small part of DNA into messenger RNA (mRNA).
             The first step in Transcription is called Initiation.  During initiation, RNA polymerase binds to the Promoter site on the DNA.
             The next step in Transcription is actually putting the nucleotides together.  A transcription bubble is made and there is a DNA-RNA hybrid strand that is held together by the RNA polymerase.  The newly created mRNA is released once the RNA polymerase reads the termination sequence on the DNA.

The next part of protein synthesis is Translation.  Translation occurs in the ribosome in the cytoplasm.  The ribosome is made of 2 protein subunits with three sites on it, Aminoacyl (A), Peptidyl (P) and Exit (E).  The Aminoacyl site is where the all but the first amino acid enters.  The Peptidyl site makes the peptide bonds.  The exit site is where the Transfer RNA (tRNA) leaves.
                The first step in Translation is called Initiation.  The ribosome will scan the mRNA for the START codon.
                 The next step is Elongation in which the tRNA comes in and binds the codon (mRNA) to the anticodon (tRNA).  The mRNA will first enter the A site and its codon will bind with the tRNA (anticodon).  The P and A sites will nab the corresponding amino acid.  The amino acids are found freely in the cytoplasm of the cell so they are nearby.  The codon and anticodons will split and a peptide bond will form between the amino acids that are left behind.  The tRNA will leave the ribosom and get another corresponding amino acid.  The ribosome will hop over to the next codon on the mRNA.  The tRNA will reenter at the A site with the corresponding anticodon on it so that it will match up with the mRNA's codon.  The process is repeated until a stop codon is met.

Once protein synthesis is done, the primary structure has been made (the chain of amino acids) and is then released from the ribosome.
Upon release from the ribosome, the secondary and tertiary structures are made automatically from the protein folding upon itself.

I'll type you a test answer that I wrote that might better explain it.  This is from my notes and from what I know.

by on Jan. 25, 2010 at 11:28 PM

I am discussing protein sythesis.

Protein synthesis is the making of necessary proteins by a cell as directed by DNA.  RNA polymerase is the enzyme that directs the entire process.  Protein synthesis is divided in two parts, transcription and translation. 

Transcription can only code for one gene, segmented DNA that codes for protein, at a time and it occurs in the nucleus or nuclear region of the cell.  During initiation of transcription, the DNA begins to unwind and the RNA polymerase binds to the promoter site of the template strand of DNA and creates a transcription bubble (ann 18 base long stretch).  The RNA polymerase brings in RNA nucleotides from teh cytoplasm and binds them in a complementary fashion to the sense strand and creates a DNA-RNA hybrid.  Transcription can only copy one gene at a time and once the RNA polymerase reads the termination sequence, the RNA half is released and is known as mRNA. 

Translation is the making of porteins from mRNA and takes place in the cytoplasm.  The ribosomes are 2 protein subunits that come together when mRNA sits between them.  Ribosomes have 3 sites, Aminoacyl (A), Peptidyl (P) and Exit (E).  All except the first tRNA enter at the first site and all peptide bonds are made at the Psite.  All RNAs leave at the E site when they are done.  The first step in translation is initiation in which the ribosome scans the mRNA for the START codon. The RNA polymerase grabs the tRNA that has the anticodon sequence for the START codon and binds them in the P site.  The rest of elongation consists of tRNAs comin in the A site and binding the anticodon to the mRNA codon.  The ribosomal RNA (rRNA) then comes in once the A and P sites are occupied and grbs the amino acids to form a peptide bond between them.  The ribosome "hops" (using ATP) along the mRNA strand for the next sequences until the STOP codon is read and termination is initiated. 

The primary structure is made and the secondary and tertiary structures begin automatically upon release as the new protein folds over on itself.

by on Jan. 25, 2010 at 11:35 PM

What class is this for?  If you don't mind me asking.  It is easier for me to explain it when I can draw it out. 

If you have any questions or if I didn't tell you what you were looking for, just let me know.  If you need to know how the protein folds on itself let me know that as well.

I hope that helped.  It is a very complicated process and is better when it can be drawn out step by step.

This is a very good animation that explains it.  It's 3 minutes long.

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