AA Confusion...

[davidianstyle]

I'm going over EK Biology section on amino acids and I just realized that something doesn't add up...

If an amino acid consists of three nucleotides, and a nucleotide consists of a phosphate group, a pentose and a nitrogenous base (total of 6C's 10H's 13O's 4N's and 3P's for one nucleotide)...how is it possible that a single amino acid is formed (ie. Glycine H2N-CH2-COOH)?

What happened to the remaining atoms? What am I missing?

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[Virgil]

I'm going over EK Biology section on amino acids and I just realized that something doesn't add up...

If an amino acid consists of three nucleotides, and a nucleotide consists of a phosphate group, a pentose and a nitrogenous base (total of 6C's 10H's 13O's 4N's and 3P's for one nucleotide)...how is it possible that a single amino acid is formed (ie. Glycine H2N-CH2-COOH)?

What happened to the remaining atoms? What am I missing?

Oooh...an amino acid isn't made from nucleotides. Nucleotides make genetic material (usually) but not amino acids. Each amino acids has an amine (which includes the nitrogen...it's the H2N in your example. I think you mixed that up with "nucleotide"), hydrogen, carboxyl, and a distinct functional group.

 

[DrBowtie]

You are forgetting the central dogma:
DNA -> MRNA -> TRNA -> AA

 

[Virgil]

You are forgetting the central dogma:
DNA -> MRNA -> TRNA -> AA

An amino acid does not "consist" of either DNA, mRNA or tRNA. In fact, these are only useful when talking about the formation of amino acid (polypeptide) chains, not the individual amino acids.

 

[DrBowtie]

An amino acid does not "consist" of either DNA, mRNA or tRNA. In fact, these are only useful when talking about the formation of amino acid (polypeptide) chains, not the individual amino acids.

Yes. I wasn't implying that.

 

[tncekm]

I'm going over EK Biology section on amino acids and I just realized that something doesn't add up...

If an amino acid consists of three nucleotides, and a nucleotide consists of a phosphate group, a pentose and a nitrogenous base (total of 6C's 10H's 13O's 4N's and 3P's for one nucleotide)...how is it possible that a single amino acid is formed (ie. Glycine H2N-CH2-COOH)?

What happened to the remaining atoms? What am I missing?

You're a little bit off on your thinking here.

Here is how polypeptides are made from DNA.

DNA codes for proteins in sets of three nucleotides called "codons". Codons are specific to an AA (note: more than one codon can code for an AA, but not the reverse).

RNA Pol makes a transcript, which is then processed, and we have mature mRNA.

mRNA attaches to a ribosome, and "translation begins".

tRNA's with an anticodon matching the codon of the mRNA in the A site and carrying the amino acids specified for by the codon on the A site will bind their anticodon to the matching mRNA codon on the A site, and the AA attached to the tRNA in the A site is attached to the AA on the tRNA next to it in the P site.

(Get a textbook for a "complete" set of steps, I don't feel like writing an enormous post on it )

So, DNA tells the ribosome which order it needs to connect the AA (via peptide bond), it doesn't actually get converted into AAs.

 

[davidianstyle]

An amino acid does not "consist" of either DNA, mRNA or tRNA. In fact, these are only useful when talking about the formation of amino acid (polypeptide) chains, not the individual amino acids.

Ok, I made a mistake...:-( amino acids don't consist of nucleotides. But isn't it true that they do consist of nitrogenous bases? ie. Glycine is GG_ (the blank represents any of UCAG). Taking the atoms of three Guanine bases also gives you way more than what is said to be in glycine. I'm not too optimistic about my confusion getting cleared up anytime soon. :-(

 

[tncekm]

Ok, I made a mistake...:-( amino acids don't consist of nucleotides. But isn't it true that they do consist of nitrogenous bases? ie. Glycine is GG_ (the blank represents any of UCAG). Taking the atoms of three Guanine bases also gives you way more than what is said to be in glycine. I'm not too optimistic about my confusion getting cleared up anytime soon. :-(

Youtube transcription and translation. It will help if you see some vids.

Amino Acids have nitrogens in them, in the form of an amide, and that amide is used in the peptide bonding of AAs.

 

[tncekm]

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

 

[Virgil]

Ok, I made a mistake...:-( amino acids don't consist of nucleotides. But isn't it true that they do consist of nitrogenous bases? ie. Glycine is GG_ (the blank represents any of UCAG). Taking the atoms of three Guanine bases also gives you way more than what is said to be in glycine. I'm not too optimistic about my confusion getting cleared up anytime soon. :-(

Nope. Amino acids have nothing to do with nitrogenous bases or nucleotides (structurally) although they all contain nitrogen.

All you have to know about amino acids is that every single one of the 20 amino acids has the same hydrogen, a carboxyl group (COOH), an amine (NH2). The only difference between each of the 20 amino acids is the distinct R group. Then you should know the classes of amino acids and which amino acids fall into what (polar, basic, nonpolar, etc.)

Check out wikipedia.