Transcript Bacteria - Legacy High School

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
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Flagella: whip-like structures used for movement
Some move like snakes, spiral, glide
Bacillus
Cocci
Spirilla
Growth and Reproduction
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Bacteria may grow and divide in 3 ways:
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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
Endospore
Conjugation
Importance of Bacteria
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Bacteria are essential to all forms of life
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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.
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E. coli: help make vitamins in intestines
Streptococci Infections
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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
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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
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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.