Bacteria can be classified by: Shape Reproductive methods Gram Staining

Bacteria has a variety of shapes including:

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?

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.

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.