Bacteria

Chapter 23 Bacteria 1

Bacteria

Blue book-Chapter 23 (460-477)

Your book- Chapter 20(572-596)


Questions? Review

• Differences bet. Prok and euk cells

a. no nucleus, or membrane bound organelles, no cell well, smaller

• What are two metabolic pathways by which cells obtain energy

a. aerobic respiration, fermentation


Objectives 23.1

• Explain the phylogenetic relationship between the domains Archaea, Bacteria, Eukarya

• Identify three habitats of Archaea• Describe the common methods used to id

bacteria• Identify five phyla of bacteria• Explain importance of nitrogen fixing

bacteria for many of earths ecosystems


Prokaryotes

Prokaryotes are the most numerous organisms on Earth. They are found almost everywhere, from the skin of a fingertip to the waters of a thermal geyser to the freezing landscape of the Antarctic. The earliest fossils of prokaryotes, which are about 2.5 billion years old, indicate that prokaryotes lived long before other forms of life evolved.


Classification review

Prokaryotes-

1. Domain Bacteria

Kingdom Eubacteria

2. Domain Archaea

Kingdom Archaebacteria

Eukaryotes

1. Domain Eukarya

a. K. Protista

b. K. Fungi

C. K. Plantae

d. K. Animalia


Two major Domains

1. Archaea- ancient (extreme environments)

2. Bacteria-

Prokaryotes- no nucleus, single-celled, live in all environments

Chapter 23 Bacteria7

Domain ArchaeaDifferent from bacteria-• cell walls (NO peptidoglycan)• Membrane lipids• Genetics and metabolism• Found in extreme harsh environments3 major groups:1. Methanogens- convert Hgas and CO2 to methane gas2. Halophiles- loves salt- live in high concentrations3. Thermoacidophiles-acidic environment, high salt,

high temps


Domain Bacteria

• Most known prokaryotes are bacteria3 basic shapes:

1. bacilli- rod-shaped2. spirilla- spiral shaped3. cocci- sphere-shaped

2 major goups1. strepto- chains2. staphlo- clusters



Gram stain• Used to put bacteria into categories based

on cell walls

• Gram-negative- have less peptidoglycan, absorb red dye, look pink/red in micro

• Gram-positive- have more peptidoglycan in cells wall and look purple



Important bacterial groups

1. Proteobacteria- nitrogen-fixing bac, convert nitrogen into usable ammonia

2. Gram-positive-

3. Cyanobacteria- use photosynthesis

4. Spirochetes- gram-neg, STDs

5. Chlamydia- gram-neg, no peptidoglycan


Objectives 23.2

• Describe the internal and external structure of prokaryotic cells

• Identify the need for endospores

• Compare four ways in which prok get energy and carbon

• Identify the different types of environments

• List three types of genetic recombination that prok use


Biology of Prokaryotes

• A look at prok cells under a light microscope show that they are very small. Such a view, however, leaves unexplained the complexity of the cells’ internal workings. Here, we will study the structure of prok cells and the many ways that they gather nutrients and energy and reproduce.


Structure and Function1. Cell wall- shape, protection, peptidoglycan2. Cell membrane/cytoplasm- selective barrier3. DNA- single closed loop of double stranded DNA ,

Plasmids are small and self-replicating double stranded

4. Capsules- outer covering of polysaccharides, protection, made of glycocalyx (fuzzy coat of sticky sugars)

5. Pili- are short hairlike projections, help to connect to other surfaces, pass DNA

6. Endospores- gram +, thick coat for protection till conditions are good

7. Flagellum- whip like motion, movementCD 16B.




Nutrition and metabolism

Heterotrophs

1. photoheterotrophs- use light energy and get carbon from other organisms

2. Chemohetertrophs- obtain energy and carbon from other organisms

Autotrophs-

1. photoautrophs- use light energy, CO2

2. chemoautrophs- use inorganic molecules, and CO2



Prokaryotic Habitats

• Live in certain habitats based on their biochemical abilities

1. Obligate anaerobes- no O2 present

2. Faculatative anaerobes- can live w/wo

3. Obligate aerobes- must have O2



Reproduction and Recombination

• Most reproduce by Binary fission

• Prok can exchange pieces of DNA that can be added to the cell’s DNA w/o reproduction recombination

To get DNA in 3 ways:

1. Transformation- take DNA from outside

2. Conjugation- 2 prok bind and pass DNA

3. Transduction- virus changes DNA

Chapter 23 Bacteria 23Binary Fission Transformation

Chapter 23 Bacteria 24conjugation

Transduction with a virus


Objectives 23.3

• Describe the ways in which bacteria can cause disease in humans

• Explain how a bacterial population can develop resistance to antibiotics

• Identify reason for recent increased in the numbers of certain bacterial infections

• Identify ways of preventing a food born illness at home

• List four industrial uses of bacteria


Bacteria and humans

Bacteria are probably best know for the disease that they cause in humans. However, most bacteria that live on human skin are harmless, and other bacteria are used biotechnologically, as in the production of yogurt. Still, other bacteria that live in soil change atmospheric nitrogen into ammonia and nitrites, which plants use for growth


Bacteria and Health

• Pathology- study of diseases (pathogen)

Bacteria can cause diseases by:

1. Exotoxins- toxic substances that bacteria secret into environment

2. Endotoxins- not released until the cell dies, causes fevers, body aches, diarrhea, (made of lipids and carbs)


Antibiotics and resistance

• Antibiotics affect bacteria by interfering with certain cellular activities

• Resistances- evolution of populations of bacteria that antibiotics can no longer kill

• Zoonosis- pass diseased from animals to humans- (http://aboundlessethic.com/?cat=46)

Foodborne-

• Industrial uses today

http://aboundlessethic.com/?cat=46

Chapter 23 Bacteria 29http://www.cdc.gov/

http://www.cdc.gov/


Review Questions1. List 4 diseases caused by bacteria (see

last slide)

2. Explain Antibiotic Resistance-

3. How is bacteria used in industry (discovery video)-

4. What is the difference between bacterial cell walls and plant cell walls?

5. Diff bet photoautroph and chemoautotroph?


6. Bacteria reproduce-

7. Name 3 groups of archaea-

8. Name some characteristics of spirochetes

9. How are bacteria classified (web quest/notes)


Review Answers1. List 4 diseases caused by bacteria (see last

slide)

2. Explain Antibiotic Resistance- evolution of populations of pathogenic bacteria that antibiotics are unable to kill

3. How is bacteria used in industry (discovery video)- bacteria are used to make and process food and chemicals. Help break down sewage and recycle carbon and nitrogen, used in mining, used to clean up oil spills, make pesticides


4. What is the difference between bacterial cell walls and plant cell walls? BC are made of peptidoglycan and pc have cellulose

5. Diff bet photoautroph and chemoautotroph? makes carbon cpds by light energy, makes carbon by breaking down inorganic sub

6. Bacteria reproduce- binary fission7. Name 3 groups of archaea-

methanogens, halophiles, theromophiles


8. Name some characteristics of spirochetes

- Gram -, sprial-shaped, aerobic and anaerobic

9. How are bacteria classified (web quest/notes)

Shape, gram stain, biochemical prop, evolutionary relationships


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Bacteria