Bacteria Our invisible friends. Germ Theory of Disease Joseph Lister – Aseptic Techniques Robert Koch – Germ Theory A specific microorganism causes.
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BacteriaOur 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 – beforeKaryon – nucleusThe 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-celledNo nucleus or organellesCircular chromosomesCell wallsReproduce mostly asexuallyAnaerobic or aerobicHeterotrophic or autotrophic
ArchaebacteriaMethane producers – anaerobicHalophiles
Halo = salt Philia = love
Thermophiles Thermo = heat
EubacteriaParasitic heterotrophs (Streptococcus)Saprophages
Sapro = death Phage = eat
Cyanobacteria (blue-green algae) Photosynthetic
Chemosynthetic autotrophs (Rhizobium)
Bacteria Structure
Chromosomes – found in cytoplasmPili – hairlike structures made of protein; help bacteria attach to surfacesCapsule – 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, acne2. secrete a toxin that can be harmful
ex. Cavities – use sugar for energy and secrete acid which can harm teeth
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