DNA STRUCTUREAND

FUNCTION

DIAMSAY, ELISHA GRACE B.MENDOZA, LINETTE M.

Rosalind Franklin used X-ray crystallography to help visualize the structure of DNA.

James D. Watson and Francis Crick, co-originators of the double-helix model.

What is DNA?

DNA, or deoxyribonucleic acid, is the hereditary material in humans and almost all other organisms. Nearly every cell in a person’s body has the same DNA.

Where is it located?

Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA or mtDNA).

FUNCTION

DNA stores an organism's genetic information and controls the production of proteins and is thus responsible for the biochemistry of an organism.

DNA STRUCTURE• The structure of DNA is

illustrated by a right handed double helix, with about 10 nucleotide pairs per helical turn

• Each spiral strand, composed of a sugar phosphate backbone and attached bases, is connected to a complementary strand by hydrogen bonding (non- covalent) between paired bases, adenine (A) with thymine (T) and guanine (G) with cytosine (C). 

Adenine forms 2 bonds with Thymine.

Guanine forms 3 bonds with Cytosine.

Sugar - Either ribose or deoxyribose (in RNA or DNA).

Nitrogenous basePurines consist of a six-membered and a five-membered nitrogen-containing ring, fused together– Adenine– Guanine

Pyridmidines have only a six-membered nitrogen-containing ring.– Uracil (RNA)– Thymine– Cytosine

Phosphates - One to three, two of which are usually hydrolyzed to provide the energy to attach the nucleotide and form the phosphodiester bond.

Base Pairing of DNA

• In a DNA double helix, each type of nucleobase on one strand normally interacts with just one type of nucleobase on the other strand. This is called complementary base pairing

• Purines form hydrogen bonds to pyrimidines, with A bonding only to T, and C bonding only to G.