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Prokaryotes Chapter 27.

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Presentation on theme: "Prokaryotes Chapter 27."— Presentation transcript:

1 Prokaryotes Chapter 27

2 Outline Prevalence of Prokaryotes Prokaryotic Diversity Prokaryotic Complexity Prokaryotic Variation Prokaryotic Metabolism Human Bacterial Diseases Benefits of Prokaryotes

3 Prevalence of Prokaryotes
Prokaryotes are the oldest, structurally simplest, and most abundant forms of life on earth. abundant for over 2 billion years before the appearance of eukaryotes 5,000 different kinds currently recognized

4 Prokaryotic Cell

5 Prevalence of Prokaryotes
Prokaryotic form bacillus (bacilli) straight and rod-shaped coccus (cocci) spherical shaped spirillum (spirilla) long and helical shaped Some bacterial colonies form spore producing structures.

6 Prevalence of Prokaryotes
Prokaryotes versus Eukaryotes unicellularity cell size chromosomes cell division and recombination internal compartmentalization flagella metabolic diversity

7 Prokaryotic Diversity
Key classification characteristics photosynthetic or nonphotosynthetic motile or nonmotile unicellular or colony-forming or filamentous spore formation by division or transverse binary fission

8 Kinds of Prokaryotes Very early, prokaryotes split into two lines Archaea and bacteria are as different in structure and metabolism from each other as either is from eukarya. Domain Archaea

9 Prokaryotic Diversity
Comparing archaebacteria and bacteria plasma membranes composed of different lipids cell wall archaebacteria lack peptidoglycan gene translation machinery archaebacteria similar to eukaryotes gene architecture bacteria not interrupted by introns

10 Prokaryotic Complexity
Prokaryotic cell surface cell wall maintains shape and protects the cell from swelling and rupturing usually consist of peptidoglycan Gram-positive - thicker peptidoglycan Gram-negative - thinner peptidoglycan flagella – slender protein - locomotion pili - hairlike structures - attachment endospores - resistant to environment

11 Gram Stain

12 Flagellar Motor

13 The Cell Interior Internal membranes invaginated plasma membrane Nucleoid region lack nucleus - genes encoded with single double-stranded DNA Ribosomes Prokaryotic ribosomes are smaller than eukaryotic ribosomes, and differ in protein and RNA content.

14 Prokaryotic Variation
Two process create bacterial variation: mutation spontaneous errors in DNA replication prokaryotic ability to mutate rapidly often has adverse effect on humans genetic recombination occurs by gene transfer from one cell to another by viruses or conjugation

15 Prokaryotic Metabolism
Autotrophs obtain carbon from inorganic CO2 photoautotrophs - sunlight chemoautotrophs - inorganic chemicals Heterotrophs obtain carbon from organic molecules photoheterotrophs - sunlight chemoheterotrophs - organic molecules

16 Prokaryotic Metabolism
How heterotrophs infect host organisms proteins secreted by type III system may be used to transfer other virulence proteins into nearby eukaryotic cells

17 Human Bacterial Diseases
Tuberculosis afflicts respiratory system and easily transmitted from person to person through the air Dental caries tooth decay caused by bacteria present in plaque high sugar diets increase tooth decay lactic acid bacteria ferment sugars and reduce pH, thus degenerating tooth enamel

18 Human Bacterial Diseases
Sexually transmitted diseases Gonorrhea (Neisseria gonorrhoeae) Syphilis (Treponema pallidum) Chlamydia (Chlamydia trachomatis)

19 Benefits of Prokaryotes
Environment chemical cycling decomposition nitrogen fixation reduces N2 to NH3 Symbiotic properties nitrogen-fixation digestive tract of animals

20 Benefits of Prokaryotes
Genetic engineering nonpolluting insect control bioremediation pollutant removal biofactories commercial production of antibiotics Bioweapons anthrax smallpox

21 Bioremediation

22 Summary Prevalence of Prokaryotes Prokaryotic Diversity Prokaryotic Complexity Prokaryotic Variation Prokaryotic Metabolism Human Bacterial Diseases Benefits of Prokaryotes


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