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Chapter 18 - Bacteria
Bacterial Structures
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DNA
Ribosomes
Cell wall
Flagellum
Pili
Gram Stain
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Gram positive
 Gram negative
Bacteria Shape
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Cocci (coccus)
 Bacilli (bacillus)
 Spirilla (spirillum)
Diplo – pairs
 Staphylo – clusters
 Strepto – chains
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Streptococcus
Movement & Support
Have cell walls to support shape and
provide protection
 Some have flagellum for movement
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Digestion/Obtaining Nutrients
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Some are autotrophs
Photosynthetic
 Chemosynthetic
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Some are heterotrophs that use organic
molecules that they engulf & breakdown
 Some use aerobic respiration and others
use fermentation (anaerobic). These
processes produce energy
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Nervous/Response
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Circular
chromosome with
DNA
 Some produce
endospores
 Some produce toxins
Circulation
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Rely on flow of cytoplasm to move
materials through cell
Gas Exchange
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Gases are exchanged directly to the
environment through diffusion
Excretion
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Waste is secreted through the cell
membrane by diffusion or exocytosis
Reproduction
Asexual – binary
fission
 Sexual – conjugation
through pilus
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What makes bacteria so great?
They reproduce rapidly
 Their DNA mutates frequently
 They can exist in extreme environments
 They are able to use substances that
other organisms cannot
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Helpful Bacteria
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Nitrogen fixation
 Recycling nutrients
(saprophytes &
decomposers)
 Medicine
 Food
Harmful Bacteria
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E. coli
Salmonella
Bacillus anthracis
Yersinia pestis
Staphylococcus
aureus
Antibiotic Resistance
Vaccines & Immunity
Vaccines consist of dead/destroyed virus
or bacteria
 Sensitizes the body to the foreign objects
 Creates antibodies that recognize foreign
antigen
 Allows the body to react more quickly
when it encounters the “real deal”
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How do we protect ourselves
from infectious agents?
Skin
 Body secretions
 Inflammation & fever
 Antibodies
 Antibiotics & vaccines
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