The Wonderful World of Microbes

Bacteria & Viruses

Chapter 19

By the end of this lesson, you wil be able to: Distinguish between the two Prokaryote Domains Describe the diversity among prokaryotes Explain the influence bacteria have on our world Describe viral composition and diversity Explain the two viral life cycles Answer if viruses should be considered living or

not

Two Prokaryotic Domains:

1) Bacteria - members of Eubacteria Kingdomo Live everywhere - saltwater, freshwater, land, inside other

organismso Surrounded by a cell wall with peptidoglycan

2) Archaea - members of the Archaebacteria Kingdomo DNA more similar to eukaryotes (eukaryotic ancestors) o No peptidoglycan in their cell wallso Live in harsh environments -

o Oxygen free - methanogenso Hot - thermophileso Salty - halophiles

Basic Bacterial Structure:

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But there are many different types…

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Prokaryotic Diversity:

Shape Spiral-shaped Rod-shaped Spherical-shaped

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Prokaryotic Diversity:

Cell Walls 2 types of cell walls

Gram positive - Thick wall of peptidoglycan holds the stain

Gram negative - Inner, thin peptidoglycan does not hold the stain

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Prokaryotic Diversity:

Movement Types

1) No movement

2) Flagella methods

3) Spiral forward

4) Slime secretions

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Prokaryotic Diversity:

Energy Obtainment1) Autotrophs

1) Photoautotroph

2) Chemoautotroph2) Heterotrophs

1) Chemoheterotrophs

2) Photoheterotrophs

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Prokaryotic Diversity:

Energy Release1) Obligate aerobe

1) Require Oxygen2) Obligate anaerobe

1) Poisoned by Oxygen3) Facultative anaerobe

1) Survive either with or without Oxygen

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E. coli

Prokaryotic Diversity

Growth and Reproduction Methods1) Binary Fission2) Conjugation3) Spore formationQuickTime™ and a

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Conjugation & Spore formation:

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Their role in our world:

Producers - base of food web

Decomposers - recycle nutrients

Nitrogen fixers - change gaseous Nitrogen (N2) into a form that plants can use and take up

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Human Uses for bacteria Sewage and petroleum

(oil) breakdown Produce fertilizers Make drugs Produce vitamins in our

intestines Make foods and

beverages

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What do you see? What do you think this is???

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Does this view help? How do you think it works?

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Homework:

19-1 worksheet Read & vocab on 19-2

The Other Microbes....VIRUSES

But are they are really????

What does it mean to be a microbe?

Viral Basics:

Disease-causing particles Contain nucleic acids (DNA or RNA) surrounded

by a protein coat (capsid) “Trick”s host cell in allowing it to bind to it,

invade, and replicate Uses the host cell’s system to replicate and then

destroys it

Tobacco Mosaic Virus

Well known Plant virus Uses the tobacco plant as

its host Studied in 1935, by

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Viral Structure

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Lysogenic Infection

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Lytic Infections

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Retrovirus

Contain RNA instead of DNA

Remain dormant for a length of time

Their RNA is copied into DNA in the host cell

Responsible for AIDS and some types of cancer

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AIDS Virus

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So should they be considered living????Characteristic Yes or No???

Reproduce?

Contain nucleic acid?

Grow and develop?

Use energy?

Respond to environment?

Change over time???

Diseases & Humans

Pathogens - disease causing; bacteria and viruses HOW DO THEY DO THIS???

1) Viruses: Attack and destroy body cells2) Bacteria:

1) Damages cells and tissues by breaking them down for food

2) Release toxins into the body

What do we do???

Viruses - AIDS, cold, hepatitus, West Nile, flu… Vaccines Anitviral drugs

Bacteria - Tuberculosis, Strep throat, tooth decay… Vaccines Antibiotics Disinfectants, sterilization or food processing

Viruses for thought….

Do you think they evolved before or after cells? Why?

How do they affect life? Viroids - Disease causing RNA molecules Prions - Disease causing proteins