Bacteria

Chapter 21

Bacteria are VERY small!

http://mrbarlow.files.wordpress.com/2008/10/bacteria-on-a-pin.jpg

Euglena 100 µm

Plant cell 35-80 µm

Animal cell 5-30 µm

Spirocheta 10 µm

Bacteria are small compared to cells with nuclei

Virus 20-200 nm

Bacteria compared to white blood cell that will eat it!

Key Concepts about Bacteria

Kingdom Monera Prokaryote=no nucleus or internal

compartments All are single cells Single circular piece of DNA

http://micro.magnet.fsu.edu/cells/procaryotes/images/procaryote.jpg

Structure of BacteriaStructure Function

Cell Wall Protects and gives shape

Outer Membrane

Protects against antibodies

Cell Membrane

Regulates movement of materials, contains enzymes important to cellular respiration

Cytoplasm Contains DNA, ribosomes, essential compounds

Chromosome Carries genetic information. It is circular

Structure of Bacteria

Plasmid Contains some genes obtained through recombination

Capsule & Slime Layer

Protects the cell and assist in attaching cell to other surfaces

Endospore Protects cell against harsh environments

Pilus Assists the cell in attaching to other surfaces

Flagellum Moves the cell

Shapes- How bacteria are identified!

Bacilli- rod shaped Spirilla- spiral shaped Cocci- sphere shaped

Staphylococci- grape-like clusters Streptococci- in chains

Bacillus bacteria are rod shaped

Spirillium bacteria have a corkscrew shape

Coccus bacteria are sphere or ball shaped

Staphylobacteria occur in clumps, such as this staphylococcus bacteria that cause common infections of cuts

Streptobacteria occur in chains, like this streptococcus bacteria

Bacterial Reproduction:Binary Fission

Conjugation

Genetic information transferred on plasmids - and sometimes antibiotic resistance

Nutrition and Growth

Autotroph- producer, makes energy from environmental sources Chemoautotrophs- Take Hydrogen from NH3 or

H2S and oxidize it using the energy to make amino acids and proteins

Photoautotrophs- photosynthetic- Uses sunlight for energy

Nutrition and Growth

Heterotroph- feed on organic material formed by other organisms Decomposers Secrete enzymes in their organic environment

and then absorb the nutrients They can metabolize their host

Endospores

Some bacteria can form endospores, which are non-replicative cell forms that are highly resistant to environmental factors.

Endospore

Gram Stain- Another way to identify BacteriaPurple= Gram Positive Pink= Gram Negative

Bacterial Cell Walls•Peptidoglycan is the material that makes up bacterial cell walls

Thicker peptidoglycan layer but not outer membrane means gram +

Thinner peptidoglycan layer with an outer membrane means gram -

How do Bacteria cause disease?

Metabolize their host for food (Heterotrophic bacteria)

Secrete a toxin which can attack other body parts (Botulism is an example)

Contain an endotoxin in their cell wall which is released when the bacterium dies. An example of this is salmonella.

How can Bacteria work to our benefit?

Digest waste at sewage plants Chemical industry- make acetone and

butanol Pharmaceutical- vitamins, antibiotics, insulin Food- yogurt, cheese, alcoholic beverages Decomposer Nitrogen fixers Symbiosis