Chapter 19Bacteria

and

Viruses

19-1I. Bacteria

A. Prokaryotic Cells unicellular with no nucleus or membrane bound organelles

i. Now two Prokaryotic Kingdoms1. Eubacteria and Archaebacteria

B. Used to be in one kingdom Monera

C. Eubacteria i. Cell walls contain peptidoglycan (carbohydrate)

iii. Live everywhere, fresh water, salt water, on/in humans

ii. May contain a second membrane

• E. coli, a Typical Eubacterium

Peptidoglycan

Cell Membrane

Ribosomes

PiliDNAFlagellum

Cell Wall

D. Archaebacteria

i. Cell walls lack peptidoglycan

ii. Live in extreme harsh environments usually with no O2

1. Halophiles = live in high concentrations of salt

2. Methanogens = live in marshes, lake sediments, digestive tract of animals

3. Thermoacidophiles = low pH, high temperature

E. Identification:

i. Shape

1. Bacilli = rod shaped

Bacilli

2. Cocci = sphere shaped

Cocci

3. Spirilla = spiral shapedSpirillaPage 473

ii. Cell walls

1. Gram Staining = used to tell the difference btw. the two types of Eubacteria

a. Gram Positive stains purple = cell wall contain thick peptidoglycan

b. Gram Negative stains pink = have thinner cell walls inside a lipid layer

iii. Movement

1. Whether they move & how they move

a. flagella, spiral forward, snake, or glide in slime

i. Heterotrophs

F. Metabolic Diversity

1. Photoheterotrophs – use sunlight for energy but need organic compounds for Carbon

2. Chemoheterotrophs – use organic compounds for energy and carbon

ii. Autotrophs

1. Photoautotrophs – use sunlight to make food

2. Chemoautotrophs – use inorganic compounds to make food ex live in hydrothermal vents deep in ocean

G. Releasing Energy

i. Obligate Aerobe = Require constant supply of O2

1. Ex. Mycobacterium tuberculosis

ii. Obligate Anaerobe = Doesn’t require O2 and may be killed by it

1. Ex. Clostridium botulinum can grow in soil and can grow in canned food that has not been properly sterilized

iii. Facultative Anaerobe = Doesn’t need O2 and is not killed by it

1. Ex. E. coli Lives w/o O2 in intestines and w/ O2 in sewage/contaminated H2O

H. Growth and Reproduction

i. Binary Fission

1. Replicates DNA and divides in halfBinary Fission

ii. Conjugation

1. Exchange genetic info. across a bridge

Conjugation

iii. Spore Formation

1. Conditions become unfavorable form endospores can remain dormant for years

Spore Formation

II. Importance of Bacteria

A. Maintaining the living world

i. Producers

ii. Decomposers break down nutrients in dead matter and the atmosphere

iii. Nitrogen Fixers convert Nitrogen gas into ammonia for plants to use

iv. Human Uses

1. Production of food/beverages, clean oil spills, remove waste products and poisons from water, live in intestines

19-3III. Diseases and Bacteria

A. Bacteria toxins can travel throughout the body

i. Streptococcus can release toxins into bloodstream and cause scarlet fever

B. Preventing Bacterial Disease

i. Vaccine = Preventative (Before exposure): weakened or killed pathogen injected into the body causing the body to produce immunity to the disease and destroy any new pathogen

ii. Antibiotics = Upon exposure; Block the growth and / or reproduction of bacteria

C. Controlling Bacteria

i. Sterilization = destroys bacteria by subjecting them to great heat

ii. Disinfectants = chemical solutions that kill pathogenic bacteria

iii. Food Storage = Refrigerate bacteria will take longer to multiply

Bacterial Diseases

Page 488 Pathogenic-means disease-causing; PATHOGENS

IV. Viruses19-2

A. Nonliving particles

B. Made of only 2 parts:

i. Capsid = outer protein coat

ii. Nucleic Acid – DNA or RNA in inner core

C. Reproduce by infecting hosts, very specific

D. Named after the disease they cause or organ they infect, Adenovirus found in adenoid tissue

i. Use numbers if virus affects the same host, T1 – T7; infect E.coli found in the intestines

E. Structure (page 479)

i. “Lunar Lander”-phages

ii. Helical

iii. Spherical with projections

iv. Polyhedral

What Is a Virus?Head

Tail sheath

DNA

T4 Bacteriophage Tobacco Mosaic Virus

Influenza Virus

RNA

Membrane envelope

Tail fiber

RNA

Capsid proteins

Capsid

Surface proteins

Page 479

F. Viral Infection

i. Lytic Infection- Immediate take-over

1. Enters cell, makes copies of itself, causes cell to lyse (burst)

ii. Lysogenic Infection- aka Latent viruses

1. Virus embeds DNA into cell’s DNA (prophage)2. Viral DNA replicates with host DNA3. Virus does not immediately take over

4. Can carry on for many years and then go into the Lytic Cycle

Viral InfectionBacteriophage injects DNA into bacterium

Bacteriophage DNA forms a circle

Lytic Infection Lysogenic Infection

Page 481

G. Retrovirus

i. Contain RNA as genetic info.

1. RNA is used to make DNA instead of RNA being copied from DNA (retro = backwards)

ii. Ex. HIV

2. DNA is inserted into the DNA of the host cell

V. Viruses in HumansA. produce disease by disrupting the body's normal equilibrium

B. attack and destroy certain cells in the body, causing symptoms of the disease

C. Others cause infected cells to change patterns of growth and development

D. cannot be treated with antibiotics

E. Symptoms may be treated with over-the-counter medicinesF. vaccines work only if used before an infection begins

Viral Diseases

Page 488

G. Viroids and Prions

i. Viroids cause disease in plants.

ii. Prions cause disease in animals.

1. single-stranded RNA molecules that have no surrounding capsids

1. contain only protein—no DNA or RNA

3. Ex. Mad cow disease

2. nerve cells become damaged

19–1

Which characteristic distinguishes eubacteria from archaebacteria? A. Eubacteria lack peptidoglycan in their cell

walls.B. Eubacteria contain peptidoglycan in their

cell walls.C. Eubacteria lack a nucleus.D. Eubacteria do not possess mitochondria.

19–1

Rod-shaped prokaryotes are called A. bacilli.B. cocci.C. spirilla.D. streptococci.

19–1

Bacteria that must live without oxygen are called A. obligate aerobes.B. facultative anaerobes.C. obligate anaerobes.D. facultative aerobes.

19–1

Prokaryotes that make their own food molecules from carbon dioxide and water but live where there is no light are called

A. photoautotrophs.B. photoheterotrophs.C. chemoautotrophs.D. chemoheterotrophs.

19–1

Bacteria that attack and digest the tissue of dead organisms are calledA. decomposers.B. nitrogen fixers.C. chemoautotrophs.D. archaebacteria.

19–2

Viruses that contain RNA as their genetic information are known as A. prions.B. oncoviruses.C. retroviruses.D. bacteriophage.

19–2

The first type of virus to be studied was the A. bacteriophage.B. tobacco mosaic virus.C. influenza virus.D. AIDS virus.

19–2Which of the following statements about viruses is true?A. Viruses appear similar to bacteria when studied

with a light microscope.B. Viruses display the essential characteristics of

living things.C. Viruses can reproduce independently if they

contain DNA.D. Viruses cannot reproduce unless they infect a

living cell.

19–2

A virus integrates its DNA into the DNA of the host cell but remains inactive for a while in A. a lytic infection.B. a lysogenic infection.C. neither a lytic nor a lysogenic

infection.D. retroviral infection.

19–2

Retroviruses are considered unique becauseA. they have RNA in their capsid and not DNA.B. they have DNA in their capsid and not RNA.C. after infection of a host cell, their RNA makes

DNA.D. after infection of a host cell, their DNA makes

RNA.

19–3

Biologists know that bacteria can cause human disease byA. entering cells and using the cell to make new

bacteria.B. producing toxic substances that interfere with

normal cell function.C. decomposing the remains of dead organisms.D. changing atmospheric nitrogen into nitrogen

compounds.

19–3

A process that destroys bacteria by subjecting them to great heat is known as A. refrigeration.B. sterilization.C. pickling.D. boiling.

19–3

Which of the following diseases is transmitted by a mosquito bite? A. influenzaB. measlesC. West Nile virusD. chickenpox

19–3

Which of the following diseases is thought to be caused by prions? A. diphtheriaB. mad cow diseaseC. tuberculosisD. smallpox

19–3

The best way to combat viral diseases isA. to use antibiotics.B. to treat individual symptoms.C. to use preventive vaccines.D. to let the disease “cure itself.”