BACTERIA

Classification

Bacteria can be classified by:• Shape • Reproductive methods• Gram Staining

Types of Bacteria

• Bacteria has a variety of shapes including:

• Cocci

• Bacilli

• Sprilli

Cocci - Round

Bacilli – Rod Shaped

Spirilli – Spiral Shaped

Growth Patterns

• Certain types of bacteria grow in characteristic patterns–Diplo: cells arranged in pairs–Strepto: cells arranged in a chain–Staphylo: cells arranged in clusters

Examples?

Reproduction

• Bacteria reproduce mainly by:

• Asexual methods.

•This happens through a type of cell division called binary fission.

Binary Fission

• Bacteria don’t have nuclei so they can’t reproduce by mitosis

• They copy their single chromosome which go to either end of the elongated bacterium.

• A partition then builds between either end of the cell and then it divides.

• Poof! An exact copy.

Binary Fission

Conjugation

• Bacteria can also exchange DNA through a process called conjugation.

• A bridge between bacteria called a pilus (plural pili) allows a short, circular section of DNA called a plasmid to be exchanged between cells.

• Pili allow genes to be transferred rapidly in a bacterial population.

Gram Staining• Bacteria can be divided into two groups based

on the presence or absence of certain types of molecules in the cell wall.

Gram Positive

• Have a thick carbohydrate cell wall and stains purple

Good Ones:

Yogurt-making bacteria, antibiotic production, pickling bacteria, digestive bacteria

Bad ones:

Some forms of tetanus, pneumonia and botulism.

Gram Negative

• Have an extra layer of lipid on the cell wall that stains pink.

• Antibiotics aren’t very effective for this bacteria. (ask if you’re interested why)

Many nitrogen-cycle bacteria are gram negative as well as cyanobacteria.

Archaebacteria

• Find the textbook section on Archaebacteria– Describe characteristics of this Kingdom– Identify some representative Archaebacteria– Explain why you think studying Archaebacteria

may be relevant today. Essentially…. Why bother??

Archaea

• Live in very difficult environments. Often classified by the environment they live in.– Halophiles: live in high-salt environments– Thermophiles: Live in high-temperature environments– Acidophiles: live in acidic environments

• Also classified by what they use for food– Methanogenic archaea make methane as a part of

their metabolism.– Chemosynthetic bacteria use other chemicals than

oxygen to help them produce energy.