DNA STRUCTRUE:
→ Genes are contained in chromosomes
→ DNA is the molecule responsible for heredity.
It has 2 functions:
to replicate itself and to direct the synthesis of proteins
,
, - Adenine and guanine are purines, nitrogenous bases with two organic rings.
- Cytosine and thymine are nitrogenous bases called pyrimidines, which have a single ring.
- Thus, purines (A and G) are about twice as wide as pyrimidines (C and T).
A purine-purine pair is too wide and a pyrimidine-pyrimidine pair too narrow to account for the 2-nm diameter
of the double helix.
Always pairing a purine with a pyrimidine, however, results in a uniform diameter:
, DNA → Genes (A piece of DNA)→ Chromosomes
Genome: Human set of DNA
sequences. The genome
contains ALL genetic
information.