VIRUSES GIVE THE WORKSHEET A TRY!! - PowerPoint Presentation

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VIRUSES

GIVE THE WORKSHEET A TRY!!

ANSWERS CAN BE FOUND IN CHAPTER 19 SECTION 2 on VIRUSES (you need to look at the WHOLE SECTION).

HELPFUL START PAGE= 474

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Bacteria & Viruses

What’s the difference??

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A little review…

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A little review…

Prokaryotes are DIVERSE

shape

,

the

chemical

nature of

their cell walls,the

way they move,

and

the way they obtain energy.

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A little review…

ARCHEABACTERIA

Live in

EXTREME

conditions.

Do

NOT have PEPTIDOGLYCAN in their cell wallsTheir DNA is so similar to Eukaryotes – possible ancestorsExample: Methanogens

EUBACTERIANEWER

bacteria

It’s

all around YOU

In our intestines

Water systems

Land

Has PEPTIDOGLYCAN

in its cell wall

E. coli

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Eubacteria come in all shapes…

Bacilli (Rods)

Cocci

(Spherical)

Spirilla

(spiral)

E. coli Streptococcus Spirillum volutan

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Eubacteria also differ in their…

Cell Walls

Have

really thick

peptidoglycan

covered ORThinner walls surrounded by a lipid layerMovement

Non moversMove slowly in their own secretionHave

flagella

that propel them

along quickly

!

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Eubacteria also differ in the way they eat…

Chemoheterotrophs

- consumers

Photoheterotrophs

-

photosynthetic & consumers

Chemoautotrophs- use carbon compounds to make food w/out sunlight.Photoautotrophs- do photosynthesis like green plants; no chloroplasts but have

chlorophyll a

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Eubacteria have different forms of release of energy

Obligate aerobes-

have to

have oxygen

; do

cell respirationObligate anaerobes- do

fermentation; “allergic” to oxygenFaculatative anaerobes- can do either one.Can live just about anywhere.

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IMPORTANCE OF BACTERIA

Producers

that capture energy by photosynthesis.

D

ecomposers—breaking

down

nutrientsEx. Nitrogen fixationHuman uses-Remove poisons, break down petroleum, used to make yogurt, mine minerals, syntesize drugsE.coli in our lower intestines, make vitamins we can’t get, further break down our food

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Viruses: “Poison” – RNA or DNA surrounded by

protein coat

INFECTS BACTERIA

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How viruses infect

Lytic

Infection-

Virus “tricks” its way into cell- CAPSID

Cell replicates viral DNA

Cell assembles new viral proteins

Cell bursts or lyses from too many viruses. Lysogenic infection-Viral DNA is inserted into the DNA of the host cell, then just sits there until something triggers the

lytic cycle.When host cell replicates, the viral DNA is replicate with it.

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Retroviruses

Nucleic acid is RNA instead of DNA

Some retroviruses cause cancer in animals (including humans).

HIV is a retrovirus (causes AIDS).

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HIV

Human Immunodeficiency Virus

Why is it so dangerous?

No cure, only treatment

Attacks/Disables key cells in immune system (helper T cells)

Host no longer able to fight off infection

May remain latent for long periods.Infected person may appear healthy but is contagious.Lysogenic Phase (latent stage)- Viral DNA inserted into host cell’s DNA and copied prior to cell division.

Lytic Phase (active stage) – Viral Proteins rapidly reproducing and infecting many cells

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Viruses vs

Cells

VIRUSES

Are not made up of cells

Can’t live without host

Don’t respond to environment

Don’t obtain or use energy

CELLS

Reproduce

Grow

Can live without host cells

Respond to their environments

Obtain energy (autotrophs or heterotrophs

Release energy (aerobic or anaerobically).

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Viruses and cells both

Reproduce

Have a genetic code (DNA or RNA)

Evolve

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Common Viral Diseases

Rhinoviruses

cause the

common cold

HPV

(Human

papillomavirus) can cause cervical cancer in women

Herpes simplex viruses cause mouth and/or genital sores, lesions, and ulcers.Influenza

viruses cause the

flu

HIV

(Human Immunodeficiency Virus)

causes

AIDS

and weakens the immune system

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Chicken pox

shingles

Rabies

Hand, foot and mouth disease

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Controlling Viruses

PREVENT

– with vaccines

TREAT

– with rest and hydration for most viral infections

Antiviral drugs available for some viral infections (limited success)

Antibiotics DO NOT work on viruses.

http://www.pbs.org/wgbh/nova/teachers/body/genetic-engineer-avian-flu.html

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Controlling Viruses

Vaccines stimulate the immune system to create antibodies that recognize a certain virus.

Vaccines will NOT cure you if you are already sick.

These antibodies patrol your body and if they recognize that virus…they call in reinforcements and your immune system goes to battle!

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How do we fight Illness?

Immune system- cells that inactivate or destroy pathogens

Nonspecific

Skin, mucus, sweat, tears

Inflammatory response

Fever

SpecificHummoral ImmunityAcquired Immunity

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Nonspecific Immunity

Skin

Mucus, saliva, tears

contain

lysozymes

Break down cell walls of bacteria

Inflammatory Response –happens if tissue damageWhite blood cells: granulocytes that engulf (EAT) pathogens

Infected tissue becomes painful and swollenFeverChemicals released by immune system raise body temperature, so that pathogens can’t survive.Heart rate increases, producing more white blood cells

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Specific Immunity

Antigens

trigger the response

Viruses, bacteria, and other pathogens that trigger immune response

“Self” and “Non-self”

Lymphocytes (T Cells and B Cells)

Tag, destroy and remember foreign bodies including pathogens

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Acquired Immunity

The production of immunity against diseases

Vaccination

Injection of a weakened form of a pathogen to stimulate immune system

Antibiotics

Compounds that kill bacteria without harming host cells (prevent bacterial reproduction)

No effect on viruses