Prokaryotic Molecular Biology: Structure and Function of DNA and the Central Dogma

Structure of DNA

• double helix

• anti-parallel

Bases

• DNA: A, T, C, G

• RNA: A, U, C, G

Pyrimidine bases

Cytosine, Thymine, Uracil

Purine bases

Adenine and Guamine

Nucleosides

sugar and base

Nucleotides

sugar, base, and phosphate

Precursors or DNA: dNMP (deoxyribonucleoside monophosphate)

• dAMP

• dTMP

• dCMP

• dGMP

Precursors for RNA: NMP (ribonucleic monophosphate)

• AMP

• UMP

• CMP

• GMP

Supercoiled DNA

• compacts the DNA (like a phone line)

• positive: twists it one direction

• negative: twists it the other direction

• DNA Gyrase: inserts negative supercoils into DNA

Genome

all the genes in a cell or a virus

Genetic elements

• chromosomes

• plasmids

• viral genomes

• transposable elements

• mitochondrial or chloroplast DNA

Chromosomes

• housekeeping genes

• presence is essential

Plasmid

a genetic element that is expendable and rarely contains genes for growth