Microbiology is defined by techniques

• Culture media for isolation and growth of organisms in pure culture
• Biochemical to study cell components
• Molecular and genetic techniques
• Microbes are the oldest form of life
• Largest mass of living material on Earth
• Carry out major processes for biogeochemical cycles
• Can live in places unsuitable for other organisms
• Other life forms require microbes to survive.

All cells have the following in common:

• Cytoplasmic membrane

  Barrier that separates the inside of the cell from the outside environment

• Cytoplasm \n Aqueous mixture of macromolecules, ions, and proteins
• Ribosomes \n Site of protein synthesis

Genetic material \n • AllcellsstoretheirgeneticinformationasDNA \n • The information is divided into functional units called genes

• Genome \n • Acell'sfullcomplementofgenes

• Chromosome \n • A genetic element carrying genes essential to cellular function

• Plasmid

• A piece of DNA that carries non-essential genes

Eukaryotes

• Membrane bound nucleus
• Membrane bound organelles
• Complex internal organization
• Division by mitosis and meiosis.

Protists – unicellular or multi-cellular

without differentiation into tissues

• Protozoa – animal-like microorganisms

• Algae – photosynthetic plant-like microorganisms

• Slime molds and water molds – filamentous

Fungi – Unicellular (yeasts), filamentous (molds), or multi-cellular (mushrooms).

Prokaryotes

No membrane bound nucleus or organelles

Simple internal structure \n Divide by binary fission

Most are unicellular

Bacteria

• Genetically diverse

• Extremely diverse metabolic styles \n • Includes both pathogens and non-pathogens

Archaea \n • Genetically and biochemically distinct from bacteria

• Also have diverse metabolism \n • Never pathogenic \n • Most famous for living in extreme environments.

Viruses

Acellular infectious particles \n Obligate intracellular parasites

Lack independent metabolism

• No ribosomes
• No ribosomal RNA

Cannot be classified with other microbes.