Bio Chemistry

BIOCHEMISTRY 3(2+1)

Lesson 28 : DNA and RNA Structures and Protein Synthesis

A comparison of DNA and RNA

DNA - Deoxyribonucleic Acid	RNA - Ribonucleic Acid
Double stranded molecule composed of nucleotides. The two strands are arranged like a twisted ladder called a double helix	Single stranded molecule, composed of nucleotides
Sugar is Deoxyribose	Sugar is Ribose
Nitrogenous Bases are: Adenine (A), Guanine (G) Cytosine (C), Thymine (T)	Nitrogenous Bases Adenine (A), Guanine (G), Cytosine (C), Uracil (U) are:
Found in the nucleus and mitochondria	Most are found in the cytoplasm, a few such as mRNA are found in the nucleus
Contains all the information needed to for the cell to make proteins. It contains the inherited characteristics of the organism.	Used in protein synthesis (see below)
Found in most cells, except some viruses (Retrovirus - See additional terms below)	Found in ALL cells
Self Replicating and directs RNA synthesis which indirectly controls protein synthesis	Generally carries information from DNA to make proteins

The Double Helix - How it fits together

The two strands of nucleotides are joined together by their nitrogenous bases through hydrogen bonds.

Guanine always bonds with Cytosine

Adenine always bonds with Thymine

(Adenine bonds with Uracil in RNA)

THUS, each strand in the double helix of DNA is complementary to the other strand.