Chapter 21 Prokaryotes Key

SW CHAPTER 21—PROKARYOTES AND VIRUSES

KEY

SHORT ANSWER 1. WWW research: http://www.cdc.gov/ncidod/EID/vol9no12/03-0288.htm According to scribes, when Alexander entered Babylon, a number of (1)____________________ fell dead at his feet. Soon after, Alexander developed severe pain, chills, weakness, delirium, and paralysis from which he died. Modern infectious disease experts have looked at those writings and concluded that Alexander died of (2)____________________ encephalitis, which is caused by a(n) (3)____________________ that was common in the Middle East. This virus was first reported in New York City in the year (4)____________________ and has rapidly spread. The virus is transmitted by (5)____________________ and not by contact with infected people. Many species of (6)____________________, (7)____________________, and reptiles can become infected with this virus. ANS: 1. 2. 3. 4. 5. 6. 7.

ravens West Nile flavivirus 1999 mosquitoes birds (mammals) mammals (birds)

PTS: 1 OBJ: Fill-in-the-Blanks TOP: 21.2 PROKARYOTIC GROWTH AND REPRODUCTION 2. Choose from the lettered terms; write the letter in the blank next to the best description. a. b. c. d.

chemoautotrophic bacteria chemoheterotrophic bacteria photoautotrophic bacteria photoheterotrophic bacteria

1.

______

2.

______

3.

______

4.

______

Use CO2 from the environment as the usual source of carbon atoms and use electrons, hydrogen, and energy released from chemical reactions to assemble chains of carbon (food storage) Use CO2 and H2O from the environment as sources of carbon, hydrogen, and oxygen atoms and use sunlight to power the assembly of food storage molecules Cannot use CO2 from the environment to construct own carbon chains; instead obtain nutrients from the products, wastes, or remains of other organisms; can break down glucose to pyruvate and follow it with fermentation of some sort Cannot use CO2 from the environment to construct own cellular molecules but can absorb sunlight and transfer some of that energy to the bonds of ATP; must obtain food molecules (carbon chains) produced by other organisms to construct their own molecules

ANS:

1

1. 2. 3. 4.

A C B D

PTS: 1 OBJ: Matching TOP: 21.2 PROKARYOTIC GROWTH AND REPRODUCTION 3. Bacteria are microscopic, (1)____________________ cells having one bacterial chromosome and, often, a number of smaller (2)____________________. The cells of nearly all bacterial species have a(n) (3)____________________ around the plasma membrane, and a(n) (4)____________________ or slime layer surrounding that. Typically, the width or length of these cells falls between 1 and 10 (5) (choose one) millimeters nanometers centimeters micrometers. Most bacteria reproduce by (6)____________________. Spherical bacteria are (7)____________________, rod-shaped bacteria are (8)____________________, and helical bacteria are (9)____________________. Gram(10)____________________ bacteria retain the purple stain when washed with alcohol. ANS: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

prokaryotic plasmids cell wall capsule (glycocalyx) micrometers prokaryotic fission cocci bacilli spirilla positive

PTS: 1 OBJ: Fill-in-the-Blanks TOP: 21.2 PROKARYOTIC GROWTH AND REPRODUCTION 4. (1)____________________ are an ancient species of photoautotroph that release (2)____________________ during photosynthesis. Some species produce (3)____________________, which are specialized cells for (4)____________________ fixation. (5)____________________, when in a symbiotic relationship with legumes, also fix (4). (6)____________________ form a group of energy parasites that are unable to produce their own (7)____________________, so they must steal it from their hosts. Fermentation by (8)____________________ species converts milk into yogurt. Clostridia and Bacilli produce (9)____________________, which are resistant to heat, radiation, and desiccation. Several species are dangerous pathogens, including Bacillus anthracis, which causes (10)____________________, and (11)____________________, which causes botulism. Myxobacteria show (12)____________________ behavior when they aggregate into a motile predatory colony. (13)____________________ are different from the Bacteria. Although prokaryotic, they make (14)____________________ proteins like eukaryotes and, also like eukaryotes, initiate protein synthesis with (15)____________________ instead of the formylmethionine used by Bacteria. Many (16)____________________, which live in highly salty environments, use the unique photopigment (17)____________________ in their photosynthesis. Some chemoautotrophic (18)____________________ live near deep ocean vents and are the base of vent food webs. (19)____________________ are symbiotic in the guts of cows and termites. ANS:

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1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19.

Cyanobacteria oxygen heterocysts nitrogen Rhizobium Chlamydia ATP Lactobacilli endospores anthrax Clostridium botulinum collective Archaeans histone methionine extreme halophiles bacteriorhodopsin extreme thermophiles Methanogens

PTS: 1

OBJ: Fill-in-the-Blanks

TOP: 21.5 ARCHAEANS

5. Match each of the numbered items with a lowercase letter designating its principal bacterial group and an uppercase letter denoting its best descriptor. a. b. c.

Archaea chemoheterotrophic Bacteria photoautotrophic Bacteria

A. Live in anaerobic sediments of swamps and in animal gut; chemosynthetic; used in sewage treatment facilities B. Endospore-forming rods that live in the soil and in the animal gut; some major pathogens C. Gram-positive nonsporulating rods that ferment plant and animal material; some are important in dairy industry D. In acidic soil, hot springs, hydrothermal vents on seafloor; may use sulfur as a source of electrons for ATP formation E. Live in extremely salty water; have a unique form of photosynthesis F. Gram-negative aerobic rods and cocci that live in soil or aquatic habitats or are parasites of animals and/or plants; some fix nitrogen G. Mostly in lakes and ponds; cyanobacteria; produce O2 using water as an electron donor H. Helically coiled, motile parasites of animals; some are major pathogens 1. 2. 3. 4. 5. 6. 7. 8.

______, ______, ______, ______, ______, ______, ______, ______,

______ ______ ______ ______ ______ ______ ______ ______

Anabaena Clostridium Extreme halophiles Lactobacillus Methanogens Rhizobium, Agrobacterium Spirochaetes, Borrelia Extreme thermophiles

ANS:

3

1. 2. 3. 4. 5. 6. 7. 8.

c, G b, B a, E b, C a, A b, F b, H a, D

PTS: 1

OBJ: Matching

TOP: 21.5 ARCHAEANS

6. a. State the principal characteristics of viruses. A virus is a noncellular infectious agent with two characteristics: 1. It consists of a nucleic acid core (either DNA or RNA) surrounded by a protein coat. 2. It can replicate only after its nucleic acid has entered and subverted the host cell’s biosynthetic apparatus to produce new viral particles. 3. The vertebrate immune system can detect and fight viruses, but the problem for the defense mechanisms is the constantly mutating viral proteins.

b. Describe the structure of viruses. • Genetic material is DNA or RNA • Coat is protein

Helical and polyhedral

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complex

c. Distinguish among the ways viruses replicate themselves. V.

Viral Multiplication Cycles A. What Happens During Viral Infections? 1. The steps of viral replication are as follows: a. Virus recognizes and becomes attached to host cell. b. DNA, or RNA, alone (or whole virus) enters cytoplasm.

c. Viral genes direct host cell into replicating viral nucleic acids, synthesizing viral enzymes and capsid proteins. d. Synthesized components are assembled into new virus particles. e. Newly formed virus particles are released from the infected cell. 2. Replication can proceed by way of two pathways: a. In the lytic pathway, the virus quickly accomplishes the five steps listed above and causes the cell to rupture (lysis), spilling its contents and the viruses. b. In lysogenic pathways, the viral genes remain inactive inside the host cell (and its

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descendants); often the genes become integrated into the host DNA only to resume their destructive viral activity later. 3. In the multiplication cycle of RNA viruses, the RNA serves as the template for synthesizing DNA using reverse transcriptase.

ANS: a. b. c.

Consist of protein coat around nucleic acid core; require living cells to act as hosts for their replication. The core can be DNA or RNA; the coat is protein and in some viruses is surrounded by a lipid envelope. Viruses may use the lytic pathway, in which the virus quickly subdues the host cells and replicates itself and descendants are released as the cell undergoes lysis; or they may use a lysogenic pathway, in which viral genes are integrated into the host's chromosomes and remain inactive inside the host cell during a period of latency, which may be a long time, before activation and lysis.

PTS: 1 OBJ: Short Answer TOP: 21.8 EVOLUTION AND INFECTIOUS DISEASES List five specific viruses that cause human illness. Norwalk and Norwalk-like viruses, Polio, hepatitis A (HA), HIV, measles, chicken pox, rabies etc

ANS: There can be multiple answers (see Table 21.2 in text). Possible answers include Herpes simplex (a herpesvirus), rhinovirus (a picornavirus), HIV (a retrovirus), West Nile virus (a flavivirus), cytomegalovirus. PTS: 1 OBJ: Short Answer TOP: 21.8 EVOLUTION AND INFECTIOUS DISEASES 8. A(n) (1)____________________ is a noncellular infectious agent consisting of a central (2)____________________ core surrounded by a protective (3)____________________. (4)____________________ contain the blueprints for making more of themselves but cannot carry on metabolic activities. Chicken pox and shingles are two infections caused by a DNA virus from the (5)____________________ category. (6)____________________ are RNA viruses that infect animal cells, cause diseases including AIDS, and follow (7)____________________ pathways of replication. During a period of (8)____________________, viral genes remain inactive inside the host cell and any of its descendants. Pathogenic protein particles are called (9)____________________. ANS: 1. 2.

virus nucleic acid

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3. 4. 5. 6. 7. 8. 9.

protein coat Viruses Herpesvirus (or Varicella) Retroviruses (HIV) lysogenic latency prions

PTS: 1 OBJ: Fill-in-the-Blanks TOP: 21.8 EVOLUTION AND INFECTIOUS DISEASES 9. Identify the viruses that cause the following illnesses by writing the name of the virus in the first blank preceding the diseases. In the second blank, categorize it as a DNA virus or an RNA virus. 1. 2. 3.

__________, __________, __________,

______ ______ ______

Common colds AIDS, leukemia Cold sores, chicken pox

ANS: 1. 2. 3.

Rhinoviruses, RNA Retroviruses, RNA Herpesviruses, DNA

PTS: 1 OBJ: Identification TOP: 21.8 EVOLUTION AND INFECTIOUS DISEASES 10. Match each numbered item with the correct lettered description. a. b. c. d.

i.

Disease breaks out irregularly, affects few organisms. Disease abruptly spreads through large portions of a population. Disease occurs continuously, but is localized to a relatively small portion of the population. Protein particle normally present in the nervous system; when misfolded may be infectious and be linked to degenerative diseases. A virus that infects a bacterium. Damage and destruction to host cells occurs quickly. Noncellular infectious agent that must take over a living cell in order to reproduce itself. Viral nucleic acid is integrated into the nucleic acid system of the host cell and replicated during this time. Any disease-causing organism or agent.

1. 2. 3. 4. 5. 6. 7. 8. 9.

______ ______ ______ ______ ______ ______ ______ ______ ______

e. f. g. h.

bacteriophage endemic epidemic lysogenic pathway lytic pathway pathogen prion sporadic virus

ANS:

7

1. 2. 3. 4. 5. 6. 7. 8. 9.

E C B H F I D A G

PTS: 1 OBJ: Matching TOP: 21.8 EVOLUTION AND INFECTIOUS DISEASES 11. ___ a. b. c. d.

Which of the following diseases is not caused by a virus? hepatitis B polio influenza syphilis

ANS: D PTS: 1 12. ___ a. b. c. d.

OBJ: Self-Quiz

Bacteriophages are ______. viruses that parasitize bacteria bacteria that parasitize viruses bacteria that phagocytize viruses composed of a protein core surrounded by a nucleic acid coat

ANS: A PTS: 1

OBJ: Self-Quiz

13. Match all applicable letters with the appropriate terms. a. b. c. d. e. f. g. h. i.

causes chicken pox, cold sores one, HIV, causes AIDS causes the common cold photosynthetic cyanobacterium parasitic bacteria, cannot produce ATP rod-shaped, used in yogurt production Archaean methanogen Archaean thermophile anaerobic, forms endospores

1. 2. 3. 4. 5. 6.

______ ______ ______ ______ ______ ______

Anabaena Chlamydia Clostridium Herpes simplex Lactobacillus Methanococcus

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7. 8. 9.

______ ______ ______

Retrovirus Rhinovirus Sulfolobus

ANS: 1. 2. 3. 4. 5. 6. 7. 8. 9.

D E I A F G B C H

PTS: 1

OBJ: Self-Quiz

14. Distinguish chemoautotrophs from photoautotrophs. Photoautotrophs a. Cyanobacteria are photosynthetic. b. Anabaena, by means of heterocysts, can fix nitrogen. c. Green and purple bacteria use hydrogen sulfide and hydrogen gas as a source of electrons for photosynthesis. 2. Chemoautotrophs a. Among the most important are the nitrifying bacteria that participate in nitrogen cycling. b. Their enzymes strip electrons from ammonia for use in generating ATP.

ANS: Answer not provided. PTS: 1

OBJ: Chapter Objectives/Review Questions

15. Describe the principal body forms of Bacteria (inside and outside).

coccus

bacillus

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spillum

Flagela, pili, capsule, cell wall, plasma membrane, cytoplasm (including ribosomes), DNA loop chromosome,

ANS: Answer not provided. PTS: 1

OBJ: Chapter Objectives/Review Questions

19. Distinguish between the lytic and lysogenic patterns of viral replication. See 6 c above.

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