1. Chapter 19
Bacteria
and
Viruses

2. 19-1
I. Bacteria
A. Prokaryotic Cells  unicellular with no nucleus or membrane bound organelles
B. Used to be in one kingdom  Monera
i. Now two Prokaryotic Kingdoms
1. Eubacteria and Archaebacteria
C. Eubacteria
i. Cell walls contain peptidoglycan (carbohydrate)
ii. May contain a second membrane
iii. Live everywhere, fresh water, salt water, on/in humans

3. E. coli, a Typical Eubacterium
Ribosomes
Cell Wall
Cell Membrane
Peptidoglycan
A bacterium such as E. coli has the basic structure typical of most prokaryotes: cell wall, cell membrane, and cytoplasm. Some prokaryotes have flagella that they use for movement. The pili are involved in cell-to-cell contact. The cell walls of eubacteria contain peptidoglycan.
Flagellum
DNA
Pili

4. 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

5. Page 473 E. Identification: Bacilli i. Shape 1. Bacilli = rod shaped
Cocci
2. Cocci = sphere shaped
3. Spirilla = spiral shaped
Spirilla
Page 473

6. 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

7. F. Metabolic Diversity
i. Heterotrophs
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

8. G. Releasing Energy
i. Obligate Aerobe =
Require constant supply of O2
1. Ex. Mycobacterium tuberculosis
Doesn’t require O2 and may be killed by it
ii. Obligate Anaerobe =
1. Ex. Clostridium botulinum  can grow in soil and can grow in canned food that has not been properly sterilized
Doesn’t need O2 and is not killed by it
iii. Facultative Anaerobe =
1. Ex. E. coli 
Lives w/o O2 in intestines and w/ O2 in sewage/contaminated H2O

9. H. Growth and Reproduction
i. Binary Fission
Binary Fission
1. Replicates DNA and divides in half
ii. Conjugation
1. Exchange genetic info. across a bridge
iii. Spore Formation
1. Conditions become unfavorable  form endospores  can remain dormant for years
Conjugation
Spore Formation

10. 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

11. 19-3 III. 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
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
i. Vaccine =

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

13. Page 488 Bacterial Diseases
Pathogenic-means disease-causing; PATHOGENS
Page 488
Bacterial Diseases
Bacteria cause disease in the body. Some of the diseases caused by pathogenic bacteria are listed in the table.

14. 19-2 IV. Viruses 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

15. E. Structure (page 479)
i. “Lunar Lander”-phages
ii. Helical
iii. Spherical with projections
iv. Polyhedral

16. What Is a Virus? Page 479 T4 Bacteriophage Tobacco Mosaic Virus
Influenza Virus
RNA
DNA
Head
RNA
Capsid
Tail sheath
Tail fiber
Membrane envelope
Surface proteins
Capsid proteins
Viruses come in a wide variety of sizes and shapes. A typical virus is composed of a core of either DNA or RNA, which is surrounded by a protein coat, or capsid.
Photo Credits: l. ©M.Wurtz/Biozentrum, University of Basel/Science Photo Library/Photo Researchers, Inc. m. ©Dr. O. Bradfute/Peter Arnold, Inc. r. ©National Institute for Biological Standards and
Control, England/Photo Researchers, Inc.
Page 479

17. F. Viral Infection
i. Lytic Infection- Immediate take-over
1. Enters cell, makes copies of itself, causes cell to lyse (burst)

18. ii. Lysogenic Infection- aka Latent viruses
1. Virus embeds DNA into cell’s DNA (prophage)
2. Viral DNA replicates with host DNA
3. Virus does not immediately take over
4. Can carry on for many years and then go into the Lytic Cycle

19. Viral Infection Page 481 Bacteriophage injects DNA into bacterium
Bacteriophage DNA forms a circle
Lytic Infection
Lysogenic Infection
Bacteriophage may infect cells in two ways: lytic infection and lysogenic infection.
Page 481

20. G. Retrovirus
i. Contain RNA as genetic info.
1. RNA is used to make DNA instead of RNA being copied from DNA (retro = backwards)
2. DNA is inserted into the DNA of the host cell
ii. Ex. HIV

21. V. Viruses in Humans
A. 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 medicines
F. vaccines work only if used before an infection begins

22. Page 488
Viral Diseases
Viruses cause disease in the body. Some of the diseases caused by viruses are listed in the table.

23. G. Viroids and Prions
i. Viroids cause disease in plants.
1. single-stranded RNA molecules that have no surrounding capsids
ii. Prions cause disease in animals.
1. contain only protein—no DNA or RNA
2. nerve cells become damaged
3. Ex. Mad cow disease

24. 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.

25. 19–1 Rod-shaped prokaryotes are called A. bacilli. B. cocci.
C. spirilla.
D. streptococci.

26. 19–1 Bacteria that must live without oxygen are called
A. obligate aerobes.
B. facultative anaerobes.
C. obligate anaerobes.
D. facultative aerobes.

27. 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.

28. 19–1
Bacteria that attack and digest the tissue of dead organisms are called
A. decomposers.
B. nitrogen fixers.
C. chemoautotrophs.
D. archaebacteria.

29. 19–2
Viruses that contain RNA as their genetic information are known as
A. prions.
B. oncoviruses.
C. retroviruses.
D. bacteriophage.

30. 19–2 The first type of virus to be studied was the A. bacteriophage.
B. tobacco mosaic virus.
C. influenza virus.
D. AIDS virus.

31. 19–2 Which 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.

32. 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.

33. 19–2 Retroviruses are considered unique because
A. 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.

34. 19–3 Biologists know that bacteria can cause human disease by
A. 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.

35. 19–3
A process that destroys bacteria by subjecting them to great heat is known as
A. refrigeration.
B. sterilization.
C. pickling.
D. boiling.

36. 19–3
Which of the following diseases is transmitted by a mosquito bite?
A. influenza
B. measles
C. West Nile virus
D. chickenpox

37. 19–3
Which of the following diseases is thought to be caused by prions?
A. diphtheria
B. mad cow disease
C. tuberculosis
D. smallpox

38. 19–3 The best way to combat viral diseases is A. to use antibiotics.
B. to treat individual symptoms.
C. to use preventive vaccines.
D. to let the disease “cure itself.”