0
$\begingroup$

How does a base pair weigh approx. 650 Da (which is two paired nucleotides) but an amino acid (3 nucleotides) weighs only approx. 110 Da ?

$\endgroup$

closed as off-topic by David, WYSIWYG, theforestecologist Apr 9 at 2:01

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "Homework questions are off-topic on Biology unless you have shown your attempt at an answer. For more information see our homework policy." – David, WYSIWYG, theforestecologist
If this question can be reworded to fit the rules in the help center, please edit the question.

  • $\begingroup$ There seems to be a misconception: amino acids do not consist of nucleotides, but are coded by them. Please look up the structures of amino acids and nucleotides and read about the process of biological translation. If the question remains, please edit your post and add your prior research on that topic. $\endgroup$ – Arsak Apr 7 at 15:28
  • $\begingroup$ Welcome to SE Biology. Please take the time to take the Tour and consult the Help on asking questions. You will see that you are expected to do some research before posting. Try looking up amino acid on Wikipedia etc. You will discover what an amino acid is. It is not a trinucleotide. $\endgroup$ – David Apr 7 at 15:30
1
$\begingroup$

In short: base pairs are not composed of amino acids but nucleotides. Base pairs are parts of the DNA, while chains of amino acids forms proteins.
Certain parts of the DNA (called genes) are transcribed to messenger RNAs (mRNA) which are sequentially translated to amino acids and the chains become proteins. 3 bases (called a codon) code for 1 amino acid.

Please look up the Central dogma, DNA, mRNA, protein and translation for further information

$\endgroup$
0
$\begingroup$

Yours is a question based on a wrong premise.

First, it is very important to note that an amino acid is not made by sticking together 3 nucleotides. However, in the process of translation, the mRNA sequence is read by groups of three nucleotides, named codons. For example, 5'-AAA-3 is a codon that anneals with the 5'-UUU-3' anticodon. So where is this anticodon?

Unlike DNA, which is double-stranded, mRNA is single stranded. Other single-stranded RNAs called tRNA contain these anticodons. In the previous case, the 5'-UUU-3' tRNA always contains the amino acid lysine on its 3' end. This is because there are special enzymes called aminoacyl-tRNA transferases that ensure that a particular tRNA always links to a particular amino acid.

Long story short, the ribosome allows the tRNAs to orientate themselves so that the amino acids they carry react and form a peptide chain. The incoming tRNAs take this growing chain of amino acids, until a special "tRNA" stops the process and the amino acid chain is "set free". Obviously, this chain once complete is not bound to any nucleotide, so once you calculate the average molecular weight of a proteinogenic amino acid you don't have to take them into account.

enter image description here

$\endgroup$

Not the answer you're looking for? Browse other questions tagged or ask your own question.