Bacteria Chapter 18

Identifying Prokaryotes Factors needed to identify a prokaryote: 1) Shape a) Bacilli: rod-shaped b) Cocci: spherical (bead-like) c) Spirilla: spiral or cork-screw shaped 2) Movement: some move, others do not Flagella: whip-like structures used for movement Some move like snakes, spiral, glide

Bacillus Spirilla Cocci

Growth and Reproduction Bacteria may grow and divide in 3 ways: 1) Binary Fission: copies DNA and divides in half; no exchange or recombination of DNA (asexual) 2) Conjugation: bridge between 2 cells; genes are exchanged between the 2 bacteria 3) Spore Formation: in harsh conditions, bacteria form spores for protection

Binary Fission Conjugation Endospore

Importance of Bacteria Bacteria are essential to all forms of life A) Decomposers: help ecosystem recycle nutrients and break down compounds in sewage treatments B) Nitrogen Fixers: convert N2 gas into form plants can use and recycles it in atmosphere C) Human Uses: food, beverages, industrial, purification, etc. E. coli: help make vitamins in intestines

Streptococci Infections Streptococci (strep) are bacteria that are commonly found harmlessly living in the human respiratory, gut and genitourinary systems. Several species are capable of causing disease in humans, including skin diseases. Impetigo Cellulitis Necrotising faciitis

E. Coli Infections Most E. coli are harmless and actually are an important part of a healthy human intestinal tract. However, some E. coli are pathogenic, meaning they can cause illness, either diarrhea or illness outside of the intestinal tract.

Meningitis Meningitis is a disease caused by the inflammation of the protective membranes covering the brain and spinal cord known as the meninges. The inflammation is usually caused by an infection of the fluid surrounding the brain and spinal cord.