Bacteria pp. 108 to 112

EUKARYOTES (TRUE NUCLEUS) (PLANT AND ANIMAL CELLS) PROKARYOTES (PRE-NUCLEUS) (BACTERIA) NucleusNo nucleus Lots of chromosomesUsually one chromosome + some plasmids MitochondriaNo mitochondria Chloroplasts in plant cellsNo chloroplasts LargerSmaller Mitotic cell divisionSimple binary fission (split into two) Flagellum in animal cells (some)Simple flagellum

Bacteria: General Info Two kingdoms: Archaebacteria (early bacteria) and Eubacteria Unicellular (organism is single- celled); can be grouped into colonies Do well in damp environments, will become inactive in dry environments No nucleus but has single chromosome and small plasmids, which is also genetic information

Archaebacteria – 3 groups Most live without O 2 in extreme environments Thermophiles – live in envs hotter than 45°C (eg. Hot springs) Methanogens – No O 2, but abundant CO 2 /H 2 ; produce methane gas – Swamps, marshes, volcanoes, intestines of mammals Halophiles – Live in salty environments (eg. Salt lakes, salt flats)

Thermophiles in hot springs of Yellowstone Nat. Park Methanogens in cow intestines is a source of fossil fuel emission. However, methane gas can be used as a source of electricity since it is a natural gas! Halophiles love salt. Middle picture is the Dead Sea!

Eubacteria & Structure Most bacteria fall into this kingdom Flagella – act as a propeller to move cell Capsule – sticky coat, protective layer (protects from host’s immune system), seen in disease-causing bacteria Pili – help bacteria attach to each other and surface, also helps with movement Genetic material – floats in cytoplasm, no nucleus, 1 chromosome and several plasmids Ribosomes, cell membrane, cell wall, cytoplasm – see Unit 1

Classifying Bacteria 1.By Shape 2.By Gram Staining 3.By whether they need O 2 to live or not 4.By the type of food they need

Classification: Shape Most bacteria are found in groups rather than individual cells. Large groups are called colonies. Spherical (cocci, sin: coccus) Rod-shaped (bacilli, sin: bacillus) Spiral (spirilla, sing: spirillus)

Classification: Gram Staining Bacteria have a polymer called peptidoglycan in cell wall. Bacterial cell walls may react with a chemical stain called Gram stain. If they do react, then they are called “Gram-positive bacteria” (more polymers = thick wall) and will be purple. If they don’t react, then they are called “Gram- negative bacteria” (less polymers = thin wall) and will be pink.

Classification: Oxygen Aerobic bacteria need oxygen to live – Eg. Tuberculosis bacteria Anaerobic bacteria do not need oxygen to live – Eg. Gangrene, botulism, tetanus bacteria Most bacteria can live with or without oxygen, such as E. coli.

Classification: Food Autotrophs – make own food using sunlight (like plants) Chemosynthetic – make own food from chemicals in their env. like methane) Heterotrophs – get food from consuming other organisms, either living or dead  most common type

Reproduction Reproduce asexually by binary fission – Parent cell begins to divide – Cell doubles its cytoplasm & cell wall making enough for 2 cells. It replicates its DNA (exact copy) – When cell has doubled all of its components, a cross-wall is formed. Parent cell begins to pinch into two. – Two daughter cells are formed. They are exact copies of each other and the parent cell.

Reproduction Some bacteria can reproduce sexually by conjugation – Two different bacteria cells (one donor and one recipient) make contact – A sex pilus (tube) is formed – One strand of a plasmid moves through pilus to the other cell. – Recipient cell makes complimentary strand of plasmid, as well as donor cell. – Bacteria separate