Bacteria (1)

structure of a prokaryotic cell

How do bacteria reproduce asexually?

• Binary Fission: DNA replicates and the cell divides in two.

How do Bacteria reproduce through genetic combination

3 ways

• transformation

• Transduction

• Conjugation

Transformation (Genetic recombination)

Receives fragments of DNA from the environment

Transduction (Genetic recombination)

• DNA carried into a cell through viruses

Conjugation (Genetic recombination)

• exchange of DNA fragments

What different methods are used to classify bacteria?

• Shape

• Gram stain reaction

• Oxygen requirements

• Feeding strategies

How is a gram stain done?

1. Stain with crystal violet

2. Add iodine

3. Rinse with alcohol

4. Stain with safranin (red dye)

Why do they stain those colors? (1)

1. Gram-positive bacteria

   1. Thick peptidoglycan layer

   2. Traps crystal violet

   3. Appear purple

Why do they stain those colors? (2)

1. Gram-negative bacteria

   1. Thin peptidoglycan layer

   2. Crystal violet washes out

   3. Safranin stains them red

Obligate aerobes

Need air

Obligate anaerobes

Don’t need air

Facultative anaerobes

Air is helpful

Aerotolerant anaerobes

Do not use oxygen but tolerate it

Microaerophiles

Require small amounts of oxygen

Photoautrophs

Energy source: light

Carbon source: CO2

Chemoautotrophs

Energy source: inorganic chemicals

Carbon source: CO2

Photoheterotrophs

Energy source: light

Carbon source: organic compounds

Chemoheterotrophs

Energy source: organic compounds

Carbon source: organic compounds

What is nitrogen metabolism?

Makes nitrogen available for other organisms

What is Nitrogen fixation?

convert atmospheric nitrogen into

ammonia

What is Heterocycst?

a specialized cell in cyanobacteria used for nitrogen fixation.

What is bioremediation?

Bioremediation is the use of bacteria to clean up environmental pollution

ex: sewage treatment and oil spills

Exotoxins

• secreted by bacteria

Endotoxins

• components of the cell wall

Koch’s Postulates 4 rules (1)

• The microorganism must be identified in all individuals affected by the disease, but not in healthy individuals.

Koch’s Postulates 4 rules (2)

• The microorganism can be isolated from the diseased individual and grown in culture.

Koch’s Postulates 4 rules (3)

• When introduced into a healthy individual, the cultured microorganism should cause disease.

Koch’s Postulates 4 rules (4)

• The microorganism must then be re-isolated from the experimental host, and found to be identical to the original microorganism.