Download Bacteria Notes

Bacteria
Our invisible friends
Germ Theory of Disease
Joseph Lister – Aseptic
Techniques
Robert Koch – Germ Theory

A specific microorganism
causes a specific disease
Bacteria are prokaryotes
Pro – before
Karyon – nucleus
The simplest forms of life are
prokaryotes.
Earth’s first cells were
prokaryotes.
Lots of Them!
Prokaryotes are Earth’s most
abundant life forms.
They can survive in many
environments.
They can get energy from many
different sources.
Prokaryote Review
 Mostly single-celled
 No nucleus or organelles
 Circular chromosomes
 Cell walls
 Reproduce mostly asexually
 Anaerobic or aerobic
 Heterotrophic or autotrophic
Archaebacteria
Methane producers – anaerobic
Halophiles
Halo = salt
 Philia = love

Thermophiles

Thermo = heat
Eubacteria
 Parasitic heterotrophs (Streptococcus)
 Saprophages
Sapro = death
 Phage = eat

 Cyanobacteria (blue-green algae)

Photosynthetic
 Chemosynthetic autotrophs (Rhizobium)
Bacteria Structure
Chromosomes – found in
cytoplasm
Pili – hairlike structures made of
protein; help
bacteria attach to
surfaces
Capsule – layer outside cell wall;
protects cell
from white blood
cells and antibiotics; keeps the
cell from drying out
Bacteria Structure
Bacteria are Named by Shape
Cocci (ball-shaped)

Streptococcus mutans
Bacillus (rod-shaped)

Clostridium botulinum
Spirilli (spiral-shaped)

Treponema palladium
Bacteria Reproduction
Binary fission – asexual;
division of bacteria into two identical cells
Conjugation – sexual; two prokaryotes attach to each other
and exchange genetic material; creates diversity
among bacteria
Bacteria Reproduction
Bacteria Reproduction
Why do we need bacteria?
Our bodies use bacteria – not harmful; help prevent
harmful bacteria from causing disease
Foods – cheese, pickles yogurt all made with bacteria
Medicines – make antibiotics such as penicillin
Disease Causing Bacteria
Only a small percentage of bacteria is harmful
Cause disease in two ways:
1. multiply quickly so the body cannot defend itself
ex. STDs, strep throat, acne
2. secrete a toxin that can be harmful
ex. Cavities – use sugar for energy and secrete
acid which can harm teeth