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PROKARYOTESDomain BacteriaDomain Archaea

(Chapter 16, sections 7-17)

I. Characteristics of Prokaryotes

• A. Sizes and shapes•

coccus bacillus

spirillum

p.334

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I. Characteristics of Prokaryotes

• A. Sizes and shapes• B. No nucleus

Bacterial Genes

• Bacteria have a single chromosome– Circular molecule of DNA

• Many bacteria also have plasmids– Self-replicating circle of DNA that has a

few genes– Can be passed from one cell to

another

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pilus

bacterial flagellum

cell wallouter capsule

plasmamembrane

cytoplasm, with

ribosomes DNA, in nucleoid

Fig. 21-2, p.334

I. Characteristics of Prokaryotes

• A. Sizes and shapes• B. No nucleus• C. Most have cell walls•

pilus

bacterial flagellum

cell wallouter capsule

plasmamembrane

cytoplasm, with

ribosomes DNA, in nucleoid

Fig. 21-2, p.334

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Prokaryotic Body Plan

bacterial flagellumpilus

capsule

cell wall

plasma membrane

cytoplasm

DNA

ribosomes in cytoplasm

Fig. 21-4, p.335

Gram +

Gram -

Relates to level of peptidoglycan in cell wall

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I. Characteristics of Prokaryotes

• A. Sizes and shapes• B. No nucleus• C. Most have cell walls• D. Flagella• E. Pili

pilus

bacterial flagellum

cell wallouter capsule

plasmamembrane

cytoplasm, with

ribosomes DNA, in nucleoid

Fig. 21-2, p.334

Fig. 21-3c, p.335

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sex pilus

Fig. 21-6, p.337

ConjugationTransfer of plasmid

I. Characteristics of Prokaryotes

• A. Sizes and shapes• B. No nucleus• C. Most have cell walls • D. Flagella• E. Pili• F. Metabollic diversity

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I. Characteristics of Prokaryotes

• A. Sizes and shapes• B. No nucleus• C. Most have cell walls • D. Flagella• E. Pili• F. Metabollic diversity• G. Reproduce by fission

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II. Prokaryotic growth and reproduction

• Growth through numbers

• Processes

Fig. 21-5, p.335

Stepped Art

Fig. 21-5, p.335

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III. Classifying Prokaryotes

• Lots of gaps, very diverse group

• Biochemical analysis

III. Classifying Prokaryotes

• Lots of gaps, very diverse group

• Biochemical analysis

• Often use numerical taxonomy/strains for comparative purposes.

p.337

DOMAIN BACTERIA DOMAIN ARCHAEA

to ancestors of eukaryotic cells

biochemical and molecular origin of life

Biochemical analysis indicated first genetic divergences occurred soon after life originated.

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IV. Domain Bacteria

• A. Representative Groups

Fig. 21-7a, p.338

Bacterial Diversity

Bacteria

• Includes most familiar bacteria

• Have fatty acids in plasma membrane

• Most have cell wall; always includes peptidoglycan

• Classification based largely on metabolism

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Bacterial Diversity

• Photoautotrophic – Aerobic (Cyanobacteria)– Anaerobic (Green bacteria)

• Chemoautotrophic– Important in nitrogen cycle

• Chemoheterotrophic – Largest group

resting spore

heterocyst

Fig. 21-8a, p.339

photo-synthetic cell

Cyanobacteria

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Proteobacteria

Rhizobium sp.

Example:Monophyletic, gram -

Chlamydia

• Parasitic within animals to obtain ATP• One genus – species produce STD

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Spirochaetes

Borelia burgdorferi(Lyme disease)

Gram positives

Not a monophyletic group

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DNA

spore coat

Fig. 21-8d, p.339

capsule around cell wall

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V. Domain Archaea

V. Domain Archaea

• A. How they differ from bacteria

• How they are similar to eukaryotes

clip

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Fig. 21-11a, p.340

•Forms

Fig. 21-11b, p.340

Archaens

Methanogens

Extreme halophiles

Extreme thermophiles

Cryophiles

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Fig. 21-12c, p.341

Smallest known cell .. Nanoarchaeum equitans