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
  Aqueous mixture of macromolecules, ions, and proteins

• Ribosomes
  Site of protein synthesis

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

• Genome
• Acell'sfullcomplementofgenes

• Chromosome
• 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
Divide by binary fission

Most are unicellular

Bacteria

• Genetically diverse

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

Archaea
• Genetically and biochemically distinct from bacteria

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

Viruses

Acellular infectious particles
Obligate intracellular parasites

Lack independent metabolism

• No ribosomes

• No ribosomal RNA

Cannot be classified with other microbes.