Showing posts with label rna. Show all posts
Showing posts with label rna. Show all posts

Wednesday, March 12, 2008

NUCLEOTIDES

NUCLEOTIDES

The nucleotides that are the building blocks of nucleic acids are formed by adding a phosphate group to a nucleoside.



Nucleotides containing ribose are known as ribonucleotides, and those containing deoxyribose are known as deoxyribonucleotides.

To summarize the structural differences between DNA and RNA:

DNA (deoxyribonucleic acid)

  • Sugar is deoxyribose
  • DNA is a polymer of deoxyribonucleotides
  • Bases are adenine, guanine, cytosine and thymine

RNA (ribonucleic acid)

  • Sugar is ribose
  • RNA is a polymer of ribonucleotides.
  • Bases are adenine, guanine, cytosine and uracil (instead of thymine)

COMPOSITION OF NUCLEIC ACIDS

COMPOSITION OF NUCLEIC ACIDS
This section of the tutorial begins to look at the composition of nucleic acids starting from the biggest subunit and going all the way down to the very chemical elements that make them up.

Nucleic acids are one of several macromolecules in the body in addition to fats, proteins and carbohydrates. So it isn't surprising that nucleic acids are built like these other macromolecules. Nucleic acids and the other macromolecules just mentioned are polymers made up of individual molecules linked together in long chains.

  • Proteins are polypeptides made up of individual amino acids linked together,
  • Carbohydrates are polysaccharides made up of individual monosaccharides linked together, and
  • Nucleic acids are polynucleotides made up of individual nucleotides linked together.

If you go even further, a nucleotide can itself be further broken down to yield three components:

  • a sugar,
  • a Nitrogen (amine) base, and
  • phosphoric acid.


As mentioned in the Introduction to this tutorial, there are two types of nucleic acids: DNA and RNA. DNA stores genetic information, and RNA allows that information to be made use of in the cell. Before we discuss the overall structure of nucleic acids as polymers, we should probably find out how their individual component parts are joined together and how DNA and RNA differ.