Prokaryotes

Think!!!!: What is the study of microorganisms called?

What is the study of bacteria called?

Remember what a PROKARYOTE IS!!!1. A unicellular organism that lacks a________________.

2. There are 3 domains of life: ________________ ________________ __________________. Of the three, prokaryotes are classified in the ____________ or _____________ domain.

How are Bacteria and Archaea same/ different?

Similarities Small (microscopic)

Lack nuclei

Have cells walls

Differences Archaea live in very HARSH/ EXTREME

environments

Cell walls of bacteria have peptidoglycan- a polymer of sugars and amino acids that surrounds the cell membrane while archaea DO NOT!

Archaea contain different lipids than Bacteria in their cell membranes

DNA sequences of archaea are closer to that of eukaroyotes than bacteria (making them more closely related to eukaryotes).

3 Ways to tell prokaryotes apart…

1.Size/ Shape

2.How they move

3.How they obtain/ release energy

Shapes

1.Bacilli- rod shaped

2.Coccus (cocci)- spherical

3.Spirilla (spirillum)- corkscrew/ spiral shaped

Energy Capture by Prokaryotes

1. Heterotroph- “_______ _______” Take in organic molecules from environment or other organisms to use as both energy and carbon supply

2. Photoautotroph- “_____ ______ ______” Use light energy to convert carbon dioxide into carbon compounds

3. Photoheterotroph- “ _________ ________ _______” Like basic heterotrops but also use light energy

4. Chemoatutroph- “ _______ _______ _________” Use energy released by chemical reactions involving ammonia, hydrogen sulfide, etc.

Energy Release by Prokaryotes

1.Obligate aerobe- “________ ______” Energy released by cellular respiration; need a steady supply of oxygen

2.Obligate anaerobe- “_____ ___ _________ _________” Energy released by fermentation (die in the presence of oxygen)

3.Facultative anaerobe- “_______ ______ _______ ____ _______” Energy released in either cellular respiration or fermentation as necessary

Prokaryote growth

Binary fission:1. Prokaryote grows

to nearly double its size

2. Replicates DNA3. Divides in half

producing 2 IDENTICAL CELLS!

If conditions for prokaryotes become unfavorable…

Many bacteria can form an endospore! It’s a thick internal wall that encoloses the DNA and a portion of the cytoplasm. Bacillus anthracis (anthrax) is one such bacterium that can do this!

Prokaryotes reproduce asexually…so how do they evolve???

2 ways!

Mutation- random change in DNA

Conjugation- exhanging genetic information by forming a hollow bridge between two bacterial cells; genetic material (in the form of a plasmid) moves from once cell to the other

Carry genes that enable bacteria to survive in new environments or resist antibiotics

Increases genetic diversity in populations of prokaryotes

Importance of Prokaryotes

Prokaryotes are ESSENTIAL in maintaning every aspect of the ecological balance of the living world. Some species also have specific uses in human industry…

3 Roles!

1. Decomposers- break down dead organisms to supply raw materials for living things…if these materials were not recovered when organisms died, life could not continue. Also, very helpful in sewage treatment!

2. Producers- photosynthetic prokarytoes (like cyanobacterium) provide food chains everywhere as producers of food and biomass

3. Nitrogen Fixers- Nitrogen is essential for plant growth, but plants can’t take it out of the atmosphere by themselves. Nitrogen fixation is the process of converting nitrogen gas into ammonia. Ammonia can then be converted to nitrates that plants use. Nitrogen-fixing bacteria and archaea provide 90% of the nitrogen used by other organisms! (i.e. Rhizobium lives on plant roots)

Human uses!

1. Food!2. Digest petroleum3. Remove human made waste products and poisons

from water4. Synthesize drugs/ chemicals

Bacteria and Disease

What you need to know…

Pathogen

A pathogen is a microorganism (virus or prokaryote) that causes disease

Fun fact: Louis Pasteur was the first to prove that bacteria do indeed cause disease (germ theory)

How do Bacteria cause disease???

2 ways:

1.Destroying living cells in the host

2.Releasing chemicals (called toxins) that upset homeostasis

How to control bacterial growth1. Physical removal –

washing hands helps dislodge bacteria and viruses

2. Disinfectants- chemicals

3. Food storage- refrigerator/ freezer

4. Food processing- boiling/ steaming/ frying

5. Sterilization by heat- above 100 degrees Celsius

Preventing/ Treating Bacterial Diseaes

Prevention: Vaccines!

A preparation of a weakened or killed pathogen or inactivated toxins

Stimulates immune system

Treatment: Antibiotics!

Block the growth and reproduction of bacteria by disrupting proteins or cell processes that are specific to bacterial cells without harming host cells

For Bacteria only!!!

i.e. Penicillin, Azithromycin, Tetracyline