Bacteria

Archaebacteria: The Extremists

• 3 types

• Type 1: Lives in oxygen free environments and produce methane gas

• Type 2: Lives in high salt environments not survivable by other organisms.

• Type 3: Live in acidic waters and sulfur springs, as well as thermal vents near the ocean floor.

Common Habitats for Archaebacteria

Eubacteria: The Heterotrophs

• Live almost everywhere organic molecules can be found (except where the archaebacteria live)

• Very diverse

• Can be found as autotrophs, heterotrophs

Heterotrophic Bacteria

• Some adapted to engulfing organic molecules.

• Others are parasites that obtain nutrients from living organisms.

• Some, called saprophytes, break down dead organisms and release organic matter back into the environment.

Photosynthetic Autotrophs

• Live in places with lots of sunlight

• Contain chlorophyll

• Most are blue green in color: Called cyanobacteria

• Credited for oxygenating our atmosphere

Chemosynthetic Autotrophs

• Make their own food but instead use inorganic materials containing sulfur and nitrogen.

• Responsible for “fixing” the nitrogen in soil.

• Many live on the roots of plants in a symbiotic relationship.

Bacterial Structure

Bacterial Parts

• Capsule: Some bacteria have a gelatinous capsule around the cell wall. Bacteria with capsules are more likely to cause disease.

• Cell Wall: Gives shape, prevents osmosis from bursting the cell.

• Chromosome: Single DNA molecule arranged in a circle. Not in a nucleus!!!!

• Flagellum: Used for locomotion.

• Plasmid: Few genes in small circular chromosome.

• Pili: Hairlike structure that allows bacteria to stick to other surfaces.

Identifying Bacteria

• Bacteria can be identified by gram staining of the cell wall.

• Gram positive bacteria turn purple, gram negative bacteria turn pink.

Bacterial Shapes

• Cocci: Spheres

• Bacilli: Rods

• Spirilla: Spirals

• Staphylo: Grapes

• Strepto: Chains

• Diplo: Pairs

Question

• What shape and growth pattern would you expect from Staphylococcus?

Bacterial Reproduction

• Binary Fission (Asexual): Copies chromosomes and divide creating an exact copy.

• Conjugation(Sexual): One bacterium uses its pili to transfer genetic information to another bacterium. This results in a bacterium with new genetic info.

Importance of Bacteria

• Not all bacteria are harmful!!!!!!

• They fix nitrogen

• They help us recycle nutrients.

• Help us produce foods like cheese, yogurt, and pickles.

• Some produce antibiotics that we use in our medicine.