virus and priods

Question 1

a virus that cause specific types of cancer, including
human cancers such as lymphomas, carcinomas, and some types of leukemia

Answer 1

oncoviruses

Question 2

The viruses that infect bacteria are known as

Answer 2

bacteriophages

Question 3

three categories of
bacteriophages, based on their shape

Answer 3

• Icosahedron bacteriophages
• Filamentous bacteriophages
• Complex bacteriophages

Question 4

an almost spherical shape bacteriophages

Answer 4

• Icosahedron bacteriophage

Question 5

bacteriophages that have a long tube formed by
capsid proteins assembled into a helical structure

Answer 5

Filamentous

Question 6

always cause what is known as the lytic cycle, which ends with the destruction (lysis)

Answer 6

Virulent bacteriophages

Question 7

bacteriophages that infect Escherichia coli are called

Answer 7

coliphages

Question 8

steps in the lytic cycle

Answer 8

attachment
penetration
assembly
biosynthesis
release

Question 9

(adsorption) of the phage to the surface of the bacterial cell what step of the lytic cycle is this

Answer 9

attachment

Question 10

In this step, the phage injects its DNA into the bacterial cell, acting much like a hypodermic needle
From this point on, the phage DNA “dictates” what occurs within the bacterial cell. T

Answer 10

penetration

Question 11

during this step that the phage genes are expressed

the host cell’s enzymes are used to make viral DNA
and viral proteins

Answer 11

biosynthesis

Question 12

the viral pieces are assembled to produce complete viral particles (virions). It is during this step that viral DNA is packaged up into capsids.

Answer 12

assembly

Question 13

this is when the host cell bursts open and all of the new virions escape from the cell

Answer 13

release

Question 14

these bacteriophages do not immediately initiate the lytic cycle, but rather, their DNA remains integrated into the bacterial cell chromosome,
generation after generation

Answer 14

temperate phages (also known as lysogenic phages

Question 15

Latent viral infections are usually limited by the defense systems of the human body—phagocytes and antiviral
proteins called

Answer 15

interferons

Question 16

have been developed to interfere with virus-specific enzymes and virus
production by either disrupting critical phases in viral cycles

Answer 16

antiviral agents

Question 17

Drugs used to treat
viral infections are
called

Answer 17

antiviral agents.

Question 18

Human Immunodeficiency Virus is a member of a genus of viruses called

Answer 18

lentiviruses

Question 19

An extremely large double-stranded DNA virus, recovered from amebas it “mimics” bacteria

Answer 19

Mimivirus

Question 20

are infectious RNA molecules that
cause a variety of plant
diseases

Answer 20

Viroids

Question 21

are small infectious proteins that apparently cause fatal neurological diseases in animals, such as scrapie

Answer 21

Prions

Question 22

Of all pathogens, ____ are
believed to be the most resistant to disinfectants.

Answer 22

prions

Question 23

1. Which one of the following steps occurs during the
   multiplication of animal viruses, but not during the
   multiplication of bacteriophages?
   a. assembly
   b. biosynthesis
   c. penetration
   d. uncoating

Answer 23

d

Question 24

2. Which one of the following diseases or groups of
   diseases is not caused by prions?
   a. certain plant diseases
   b. chronic wasting disease of deer and elk
   c. Creutzfeldt-Jacob disease of humans
   d. “mad cow disease”

Answer 24

a

Question 25

3. Most procaryotic cells reproduce by:
   a. binary fission.
   b. budding.
   c. gamete production.
   d. spore formation.

Answer 25

a

Question 26

4. The group of bacteria that lack rigid cell walls and
   take on irregular shapes is:
   a. chlamydias.
   b. mycobacteria.
   c. mycoplasmas.
   d. rickettsias.

Answer 26

c

Question 27

6. Which one of the following statements about rickettsias is false?
   a. Diseases caused by rickettsias are arthropod-borne.
   b. Rickets is caused by a Rickettsia species.
   c. Rickettsia species cause typhus and typhuslike
   diseases.
   d. Rickettsias have leaky membranes

Answer 27

b

Question 28

7. Which one of the following statements about
   Chlamydia and Chlamydophila spp. is false?
   a. They are obligate intracellular pathogens.
   b. They are considered to be “energy parasites.”
   c. The diseases they cause are all arthropod-borne.
   d. They are considered to be Gram-negative bacteria

Answer 28

c

Question 29

10. An organism that does not require oxygen, grows
    better in the absence of oxygen, but can survive in
    atmospheres containing some molecular oxygen is
    known as a(n):
    a. aerotolerant anaerobe.
    b. capnophile.
    c. facultative anaerobe.
    d. microaerophile.

Answer 29

a