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

Cocci Spirilla

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.