Prokaryotes Ms. Cole

Prokaryotes What do you know?

We are familiar with the harmful bacteria… Tuberculosis Cholera STD’s Bubonic plague Tuberculosis Cholera STD’s food poisoning But what about the beneficial bacteria. Nitrogen fixers Bioremediation Pharmaceutical & food industries

Most Common Shapes Cocci (spherical) Bacillus (rod-shaped) Spiral Spirillum (rigid helix) Spirochete (flexible helix) Vibrios (comma shaped)

Micrococcus coccus bacteria

Salmonella bacilli bacteria

Spiroplasma spirilla bacteria

Most prokaryotes have diameters in the range of 1-5 µm largest prokaryote discovered so far has a diameter of 0.75 mm. It is a sulfur-metabolizing marine bacterium from coastal sediments off Namibia. Fig. 26.4 Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

Bacteria and Archaea

Archaebacteria primitive prokaryotes unicellular found in the harshest environments on Earth: sometimes called extremophiles

Bacteria “true bacteria” mostly unicellular; some colonial or filamentous Peptidoglycan in cell wall

Cell walls in Bacteria Gram Staining Gram-positive - purple Very thick peptidoglycan Gram-negative - pink Thin layer of peptidoglycan Outer membrane Capsule Surrounding the cell wall Increased resistance to host defenses

Gram-positive cell wall

Gram-negative cell wall

Other Bacterial Structures Pili Protein structures that extend from the cell Help bacteria adhere to surfaces Flagella Produce a rotary motion Basal body, hook, and filament Taxis Chemo & photo

Bacterial flagellum

Review Genetic material Asexual reproduction Circular DNA molecule Plasmids Asexual reproduction Binary fission Budding Fragmentation

Gene Transfer Transformation Transduction Conjugation Intake of DNA fragments Transduction virus carries bacterial DNA between cells Conjugation Direct transfer of genes from one prokaryote to another

Metabolic Diversity Heterotrophs Autotrophs Photoheterotrophs Chemoheterotrophs Feed on dead organic matter Autotrophs Photoautotrophs Chemoautotrophs

Oxygen Use Most bacteria are aerobic Facultative anaerobes use oxygen if it is available Obligate anaerobes carry on metabolism only anaerobically

Archaea - Extremophiles Methanogens Produce methane gas Anaerobic environments Extreme halophiles Inhabit saturated salt solutions Extreme thermophiles Inhabit environments over 100°C

Symbiotic Review Mutualism Commensalism Parasitism

Disease and Microbes 1/2 of human disease is caused by bacteria some are opportunistic Pathogens Koch’s postulates Exotoxins Endotoxins

Koch’s Postulates 1. Find the same pathogen in each diseased individual. 2. Isolate the pathogen from a diseased subject and grow it in pure culture. 3. Use cultured pathogen to induce disease in experimental animals. 4. Isolate the same pathogen in the diseased experimental animal.

Antibiotics 1928 - Alexander Fleming discovers that Penicillium mold produces penicillin Breaks peptidoglycan cross links endospores

Copyright © 2002 Pearson Education, Inc Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

Table 27.3, continued Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

Quiz-page 2 List and describe at least 3 sources of genetic variation in bacteria. List the four nutritional categories for bacteria. Define what each uses as an energy source and as a source of carbon atoms. What are the 3 fundamental symbiotic relationships we have discussed. Briefly explain their differences. List two of the three scientists who are remembered for their research on the microbial causes of disease. Give a specific example of what your listed scientists discovered.

Quiz-page 3 What is nitrogen-fixation? What genus of bacteria are responsible for this important part of the nitrogen cycle? Which family of plants share a mutualistic relationship with the aforementioned bacteria? Who discovered penicillin? What is the target of its action? Why are Gram-positive bacteria more susceptible to this action than are Gram-negative bacteria? What characteristics make a protist “animal-like”, “plant-like”, or “fungus-like”? Give an example of a protist in each of these groups. Most fungi are either decomposers or parasitic. However, there are two groups of mutualistic fungi that we discussed. Choose one of these mutualistic relationships, give both organisms in the relationship and tell how each one is benefited.