Micro Chapter 13

Front 1

Why do we classify viruses as obligatory intracellular parasites?

Back 1

viruses absolutely require living host cells to multiply.

Front 2

List the 4 properties that define a virus

Back 2

1. contains DNA or RNA (never both)

2. has a protein coat surrounding the nucleic acid

2. multiplies inside a living cell using the synthetic machinery of the cell

3. causes the synthesis of virions

Front 3

What is a virion?

Back 3

a fully developed virus particle that transfers the viral nucleic acid to another cell and initiates multiplication

Front 4

What are the 4 morphological classes of viruses?

Back 4

1. polyhedral

2. helical

3. enveloped

4. complex

Front 5

A virus with RNA-dependent RNA polymerase

Back 5

synthesizes double-stranded RNA from an RNA template

Front 6

An example of lysogeny in animals could be

Back 6

latent viral infections

Front 7

which of the following would be the first step in the biosynthesis of a virus with reverse transcriptase?

Back 7

a complementary strand of DNA must be synthesized from an RNA template

Front 8

What 4 things regulate the ability of a virus to infect an organism?

Back 8

1. The host species

2. the type of cells

3. the availability of an attachment site

4. cell factors necessary for viral replication

Front 9

True of False. A viral species is defined on the basis of the disease symptoms it causes.

Back 9

False

Front 10

A viral species is a group of viruses sharing the same genetic information and ecological_________( host range).

Back 10

niche

Front 11

The viruses that cause rabies and Ebola hemorrhagic fever are_________ viruses which have relatively long rodlike shapes.

Back 11

helical

Front 12

Phage DNA that has been inserted into the circular bacterial DNA during the lysogenic cycle is called a_________

Back 12

prophage

Front 13

True of False. Retroviruses, including the virus that causes AIDS consist of single-stranded RNA that is used to produce DNA.

Back 13

True

Front 14

Certain cell lines, called diploid cell lines, developed from human embryos can be maintained for about____generations and are widely used for culturing viruses that require a human host.

Back 14

100

Front 15

The period during viral multiplication when complete, infective virions aren't yet present is called the ________ period.

Back 15

eclipse

Front 16

In some viruses, the capsid is covered by an__________, which usually consists of some combination of lipids, proteins, and carbohydrates.

Back 16

envelope

Front 17

True of False. Typically, persistent viral infections are fatal.

Back 17

True

Front 18

In 1990, a way to infect mice with HIV was found when__________ mice were grafted to produce human T cells and human gamma globulin.

Back 18

immunodeficient

Front 19

Some plant diseases are caused by_______, which are short pieces of naked RNA only 300 to 400 nucleotides long, with no protein coat.

Back 19

viroids

Front 20

True of false. Influenza A viruses are found in many different animals, including birds, pigs, whales, horses, and seals. Sometimes influenza A viruses seen in one species can cross over and cause illness in another species.

Back 20

True

Front 21

Oncogenes were first identified in cancer-causing________ and were thought to be a part of their normal genome

Back 21

viruses

Front 22

True or False. Some viral capsids contain both DNA and RNA.

Back 22

False