Chapter 19 Bacteria and Viruses 19-1 BACTERIA 19-2 VIRUSES 19-3 DISEASES CAUSED BY BACTERIA AND...

Chapter 19 Bacteria and Viruses

19-1 BACTERIA19-2 VIRUSES19-3 DISEASES CAUSED BY BACTERIA AND VIRUSES

19-1 Bacteria

Bacteria are prokaryotes- unicellular organisms that lack a nucleus.

Classification was the Kingdom Monera

Now, in two separate Kingdoms: Eubacteria Archaebacteria

Bacteria

What’s the Difference? Eubacteria- new bacteria

Example: Escherichia coli (E. coli)

Found water, land, on and in us.

Archaebacteria- ancient bacteriaExamples: MethanogensFound in harsh environments:thick mud, digestive tracts of

animals, hot springs

Identifying Prokaryotes

Shape Cocci – spherical Bacilli – rod

shaped Spirilla - spiral

How do they obtain energy?

Most are heterotrophs and many are autotrophs

Types of heterotrophs: “other” Chemoheterotrophs (chemical) Photoheterotrophs (light)

Types of autotrophs: “self” Photoautotrophs (surface of lakes,

oceans) Chemoautotrophs (deep ocean)

Growth and Reproduction Can divide every 20 minutes! Two ways to reproduce:

Binary fission – dividing in half Conjugation – form bridge and exchange

DNA

When conditions become unfavorable: Spore formation – help it survive in

extreme conditions, such as heat, dryness, lack of nutrients.

Binary fission

conjugation

Spore formation

Importance of bacteria

Decomposers – Help ecosystem

recycle nutrients by breaking down dead tissue

Help in sewage treatment

Human Uses

Used in industry – clean up oil spills Remove wastes and poisons from water Make drugs Used in food

19-2 Viruses

Viruses are composed of a core of DNA or RNA surrounded by a protein coat (capsid)

Virus means poison

Virus Structures

T4 BacteriophageTobacco Mosaic

Virus Influenza Virus

RNACapsid

Surfaceproteins Membrane

envelope

RNA

Capsidproteins

Head

Tail sheath

DNA

Tail fiber

How does a Virus work?

Proteins of virus bind to receptors on the surface of a cell.

Cell gets “tricked” into letting the viral DNA in.

Cell then transcribes and translates viral genes.

Bacteriaphage- infects bacteria

Viral Replication

Two different processes can occur:

Lytic Cycle: viral DNA enters host, copies are made, and cell lyses (bursts).

Lysogenic Cycle: viral DNA enters host, viral genes are replicated indefinitely. Prophage- viral DNA incorporated in cell’s

DNA

The Lytic Cycle...

The Lysogenic Cycle...

Both Cycles...

Retroviruses

Retrovirus- contains RNA as its genetic information

Genetic info is copied backwards from RNA to DNA.

“Retro” means “backwards”

Ex. AIDS is caused by a retrovirus (HIV)

Comparison…

19-3 Diseases caused by Bacteria and Viruses

Disease causing agents are pathogens

Bacteria produce disease in one of two ways:Break down cells for foodRelease toxins (poisons)

Examples for food or toxin release

TB – tuberculosis – destroys lung tissue

Strep throat - releases toxins into blood stream

SMALL POX

COLD VIRUS

EBOLA

FLU

Tooth decay

Lyme disease

Tetanus

Tuberculosis

Salmonella food poisoning

Pneumonia

Cholera

Streptococcus mutans

Borrelia burgdorferi

Clostridium tetani

Mycobacterium tuberculosis

Salmonella enteritidis

Streptococcus pneumoniae

Vibrio cholerae

Regular dental hygiene

Protection from tick bites

Current tetanus vaccination

Vaccination

Proper food-handling practices

Maintaining good health

Clean water supplies

Disease Pathogen Prevention

Section 19-3

Common Diseases Caused by Bacteria

Diseases caused by Bacteria

Controlling Bacteria

Sterilization – using high temperatures

Disinfectants – chemical solutions

Food storage and processing – storing in fridge or cooking food

Preventing Bacterial Disease

Vaccine – weakened or killed pathogenExamples – meningitis, whooping

cough

Antibiotics – block the growth and reproduction of bacteriaExamples- Penicillin or tetracycline

Oncogenic viruses

Retrovirus

Adenoviruses

Herpesviruses

Poxviruses

DNA

RNA

DNA

DNA

DNA

Cancer

Cancer, AIDS

Respiratory infections

Chickenpox

Smallpox

Type of Virus Nucleic Acid Disease

Section 19-3

Common Diseases Caused by Viruses

Diseases caused by Viruses

Viral disease in humans

Cannot be treated with antibiotics

VaccinesExamples – polio, measles, mumps,

chicken pox, hepatitis b