Viruses and Bacteria

• Viruses are made of two parts–A protein coat called a capsid–Genetic material, can be DNA or

RNA• Viruses that infect bacteria are

called bacteriophages.

Viral infection cycles

• Lytic: destroys the host cell• Lysogenic: allows the host cell to

reproduce with the virus DNA incorporated into its own DNA

Bacteria and Archae

• Both are prokaryotes. This means they lack a nucleus and membrane bound organelles.• Archae: primitive, live and thrive in

harsh conditions• Bacteria: what we think of when we

hear the term bacteria

Oxygen

• Obligate aerobes: bacteria that require oxygen to live• Facultative aerobes: can survive

whether oxygen is present or not• Obligate anaerobes: are poisoned by

oxygen

Parts

• Plasmid: circular bacterial DNA. It can reproduce separately from the cell’s main chromosome.• Flagellum: allows the cell to move• Cell wall: surrounds the cell.

Penicillin works by acting against the cell wall.

More parts

• Pili: tiny hairs. Allow a bacteria to stick to surfaces.• Capsule: protective waxy coating

around the cell wall

Reproduction

• Binary fission: cell divides• Conjugation: cells exchange DNA• Endo spore: has a thick protective

wall to protect against harsh conditions.

Q: Is conjugation sexual or asexual?

Geoffery

Gram stain

Penicillin

• Remember, penicillin acts against the cell wall. In gram negative bacteria, the cell wall is protected by the outer membrane. So penicillin is only effective against gram positive bacteria such as Strep or Staph.

Shapes

• Cocci: round• Bacilli: rod• Spirillum: spiraled

Mixture

Useful bacteria

• E. coli in your intestine• Skin bacteria• Digesting oil• Decomposers• Fixing carbon or nitrogen

Harmful bacteria

• Normal bacteria where they are not normally present.• Pathogens: cause disease• Superbugs: strong antibiotic

resistance.