Prokaryotes

Chapter 27

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Kingdom Monera

Prokaryotes Unicellular (Single-celled)

organisms that lack membrane-bound organelles and nuclei

Divided by 1. Domain2. Nutritional Classification3. Reactivity with Oxygen

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Domain Classification

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Nutritional Classification

AUTOTROPHS

1. Photoautotrophs Photosynthetic autotrophs – Like plants Light energy Energy (ATP) Carbon dioxide organic compounds (Glucose)

2. Chemoautotrophs Inorganic substances Energy (ATP) Carbon dioxide organic compounds (Glucose

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Nutritional Class (Page 2)

HETEROTROPHS

3. Photoheterotrophs Light energy Energy (ATP) Get carbon from consuming other organisms

3. Chemoheterotrophs Get both carbon & energy from consuming other

organisms

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Reactivity with Oxygen

Whether they must react with O2, must be in absence of O2, or they can be in absence or not of O2

Obligate aerobe – Require O2 for respiration

Obligate anaerobe – O2 is a poison to them

Facultative anaerobe – Prefer to use O2, but don’t need to use it to live

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Questions

Which of the 3 classifications is appropriate for humans?

What would you call something that uses light for energy, but must obtain carbon in an organic form?

Aerobes would do what form of catabolism?

What about anaerobes?

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Roles of Prokaryotes

Decomposers – recycle dead organic manner

Pathogens – organisms that cause disease

Nitrogen Fixation Atmospheric N2 NH4

ONLY way to fix nitrogen into organic systems

Play a vital role in genetic engineering E. Coli is used to manufacture human insulin

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Bacteria’s Roles (Page 2)

Symbionts in the gut – Manufacture vitamins Digest cellulose Digest Food

Bioremediation – remove pollutants

Used in production of cheese & yogurt

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Symbiotic Roles

Symbiotic – relationships with other species Mutualism – Both symbionts benefit

Pollinators & Flowering plants

Commensalism – One organism benefits other is unharmed Fern growing in the shade of a tree

Parasitism – One benefits at the expense of another

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Antibiotics

Chemicals that kill prokaryotes

Usually produced by fungi

NOT effective against viruses

Many plasmids confer resistance to different antibiotics

MDR-TB – Multi-Drug Resistant (resistant to multiple antibiotics) Tuberculosis bacteria

XDR-TB – eXtremely-Drug Resistant (resistant to almost every antibiotic) Tuberculosis bacteria

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Archaebacteria

Unicellular

Prokaryotes

No Peptidoglycan in their cell walls

Able to live in extreme environments

Resemble the first cells on Earth Extreme Halophiles – Salt lovers Extreme Thermophiles – exist in extreme temperatures (high

temperatures) Methanogens – Use CO2 to oxidize H2

Produce methane as a by product

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Examples of Archaebacteria

Thermoacidophiles

Hot Springs - Thermophiles

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Eubacteria

Broadly categorized as Gram-negative or Gram-positive

Due to whether the bacterium is able to take up Gram’s stain

Gram-positive – large amount of peptidoglycan in cell wall Susceptible to antibiotics

Gram-negative – structurally more complex cell wall Contains less peptidoglycan Outer membrane contains lipopolysaccharides

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5 Important Bacterial Subgroups

Proteobacteria

Chlamydias

Spirochetes

Gram-Positive Bacteria

Cyanobacteria

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Proteobacteria

Includes photoautotrophs, chemoautotrophs, and heterotrohps

Some are aerobic, others are anaerobic

Nitrosomonas – Nitrogen fixing bacteria

Examples: Escherichia coli (E coli) – benign & pathogenic Vibrio Cholerae – Cholera Rhizobium – live in roots of legumes

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Chlamydias, Spirochets

Gram-negative like proteobacteria

Chlamydias ALL are parasitic Lack peptidoglycan Chlamydia = most common STD or VD

Spirochetes Helical shape Move by rotating internal flagella-like

filaments Syphilis and Lyme disease Others are free-living (not parasitic or

pathogenic)

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Gram-positive Bacteria

Diversity rivals proteobacteria

Streptomyces – source of many antibiotics

Bacillus anthracis

Clostridium botulinum

Mycoplasms – bacteria that lack cell walls (WTF?) Synthetic organism?

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Cyanobacteria

ONLY photoautotrophs

Plant-like photosynthesis

May have heterocytes – can fix nitrogen