Notes Ch 19­Baceria and Viruses.notebook

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March 22, 2011

Apr 11­6:18 PM

Chapter 19: Bacteria and Viruses

Microscopic life covers nearly every square centimeter of Earth

There are microorganisms of different sizes and shapes in a single drop of pond water

Prokaryotes: the smallest and most common microorganisms; unicellular; don't have a true nucleus

Prokaryotes were once placed in the kingdom Monera, but today they are divided into Eubacteria and Archaebacteria kingdoms

Apr 11­6:18 PM

Eubacteria: Wide range of prokaryotic organisms

Live almost everywhere (fresh water, salt water, inside human body...)

Surrounded by cell wall containing peptidoglycan (carbohydrate)

Archaebacteria: ancient bacteria that live in extreme environments

Surrounded by cell wall that does not contain peptidoglycan. They also contain different membrane lipids than eubacteria and their DNA sequences are more like eukaryotes than those of eubacteria. (Scientists think they are ancestors of eukaryotes)

Apr 11­6:18 PM

Identifying Prokaryotes: (How do you tell them apart?)• Shape• Chemical nature of the cell wall• The way they move• The way they obtain energy

Shape:1. Bacilli: Rod Shaped

2. Cocci: Spherical Shaped

3. Spirilla: Spiral and corkscrew Shaped

Apr 11­6:18 PM

Cell Walls: Stains are used to determine if the cell walls contain Peptidoglycan

Movement: Some move using flagella or lash, snake or spiral forward or glide along a slimelike material they secrete, some don't move at all

http://www.youtube.com/watch?v=BWVHGviSiMs&NR=1

Apr 11­6:18 PM

Energy: They have many ways of getting and using energy. Most are heterotrophs. Others are autotrophs.

Heterotrophs: must consume organic molecules for energy and a supply of carbon (chemoheterotrophs). Most animals, including humans, are this type. Some are photoheterotrophs which use sunlight for energy but they also need to take in organic compounds for the carbon.

Autotrophs: Photoautotrophs use light energy to convert carbon dioxide and water into carbon compounds and oxygen. They live where light is abundant. Cyanobacteria are one type. Chemoautotrophs make organic carbon from carbon dioxide and don't require light. Instead, they use energy from chemical reactions. Some live near volcanic vents.

http://www.youtube.com/watch?v=4LoiInUoRMQ

Apr 11­6:18 PM

Releasing Energy:

Obligate aerobes: are obligated or required to have oxygenExample: Mycobacterium tuberculosis (causes tuberculosis)

Obligate anaerobes: must live in the absence of oxygenExample: Clostridium botulinum (causes botulism)

Facultative anaerobes: can survive with or without oxygenExample: E.Coli

Notes Ch 19­Baceria and Viruses.notebook

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March 22, 2011

Apr 11­6:18 PM

Growth and Reproduction:

Binary Fission: Asexual reproduction where the bacterium grows to double it's normal size, replicates its DNA and divides in half, producing identical cells

Mar 22­11:09 AM

Conjugation: Reproduction where cells exchange genetic information

Mar 22­11:09 AM

Spore Formation: When conditions are unfavorable, many bacteria form spores (endospore) that have a thick internal wall that encloses its DNA. The spores can remain dormant for a long time until conditions are favorable. This helps them survive harsh conditions

Example: Bacillus anthracis (causes anthrax)

Apr 11­6:18 PM

Why are Bacteria Important?

They are vital to the living world. Some are producers that capture energy by photysynthesis. Others are decomposers that break down the nutrients in dead matter and the atmosphere. Others have human uses.

Decomposers: break down dead organic matter.

Nitrogen Fixers: Plants need nitrogen fixing bacteria to change nitrogen gas into usable nitrates and nitrites in the soil

Human Uses: Bacteria are used to make food and beverages. Some can also digest oil and remove wastes from water. Some help mine minerals from the ground and synthesize drugs and chemicals and vitamins for humans.

Mar 22­11:12 AM

Bacterial Diseases (pathogens)

Lyme Disease­ carried by ticksTuberculosis

Bubonic Plague

Apr 11­6:18 PM

Viruses: "virus" is Latin for poision.

Viruses are nonliving particles made of nucleic acid, protein and in some cases, lipids

They can reproduce only by infecting living cells

They are so small, they can only be seen with powerful electron microscopes

The protein coat surrounding the virus is called the capsid

Bacteriophages are viruses that infect bacteriahttp://www.youtube.com/watch?v=9hzUjx_oD8E&feature=related

http://www.youtube.com/watch?v=A409yO­G1Mk&feature=related

Notes Ch 19­Baceria and Viruses.notebook

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March 22, 2011

Mar 22­11:18 AM

HIV Virus

Mar 22­11:19 AM

Viral Life Cylce

Mar 22­2:15 PM

Retrovirues­ RNA is the hereditary molecule instead of DNA.

Retroviruses use an enzyme called REVERSE TRANSCRIPTASE to convert the RNA to DNA.

Apr 11­6:18 PM

Viral Diseases in Humans: viruses produce disease by disrupting the body's normal equilibrium. They CANNOT be treated with antibiotics. The best way to protect yourself from a virus is prevention. Vaccines are one way to protect yourself.

FluAIDSChicken PoxHepatitis BWest Nile

Viruses can infect plants and animals

Viroids: single stranded RNA molecules that have no capsid

Prions: Particles that don't have DNA or RNA. They are protein infectious particles and cause disease by forming protein clumps (Example: Mad Cow Disease)

Apr 11­6:18 PM

Pathogens: disease causing agents

Vaccine: a preparation of weakened or killed pathogens to prevent an organism from contracting a disease

Antibiotics: compounds that block the growth and reproduction of bacteria

Ways to control bacterial growth: Sterilization by heat, disinfectants, and food processing