Cells and Nucleic Acids.
Cells carry information in the chromosomes to reproduce, either new offspring or to replace old cells. This is stored in the Nucleus.
DNA - Deoxyribonucleic acid.
RNA - Ribonucleic acid.
Both of which are polymers!
* Single units are called nucleotides or mononucleotides.
Each have a 3 part structure:
- a five carbon pentose sugar,
- a phosphate group,
- and a nitrogen containing base.
Nitrogen containing bases come in two forms. Single ringed, pyrimidines or double ringed, purines.
Pyrimidines are Cytosine and Thymine.
Purines are Adenine and Guanine.
Thymine is replace by Urasil in RNA.
Structure of Nucleic Acids.
- Phosphate groups make the acid, acidic.
- The sugar and base are joined together by a condensation reaction.
This is how mononucleotides are joined as well. The complementary bases, (as seen below,) are joined by hydrogen bonds and this helps form the double helix.
Adenine with Thymine,
Guanine with Cytosine.
RNA - one strand, twisted or straight.
DNA - two strands, twisted unless being copied.
For every twist in DNA there are 10 complementary pairs. Each strand is named either 5', (5 prime,) or 3', (3 prime,) due to which carbon number the phosphate group is joined to.