Micro: Ch 10 Fundamentals Of Virology

Front 1

Because viruses are incapable of replicating outside of a host, they are called-----

Back 1

obligate intracellular parasites

Front 2

What is the size of the largest viruses?

Back 2

The largest viruses are 1/25 the sizeof the smallest bacterium.

Front 3

What are the bacterial viruses called?

Back 3

Bacterial viruses are called bacteriophages or phages.

Front 4

How does a bacteriophage penetrate the host cell wall.

Back 4

In addition to the attachment factors they use to adhere to the host cell, bacteriophages also often have a needlelike tube that they use to propel through the bacterial envelope and inject their nucleic acid inside the host cell.

Front 5

capsomere (define)

Back 5

A viral protein that forms the coat around the viral nucleic acid

Front 6

capsid (define)

Back 6

The protein shell made of capsomeres

Front 7

Nucleocapsid (d)

Back 7

capsid covering plus the nucleic acid

Front 8

envelope (d)

Back 8

an additional coverage made of membrane from the host cell and viral proteins

Front 9

virion (d)

Back 9

an intact viral particle with its appropriate coating layers

Front 10

icosahedron (d)

Back 10

twenty identical sides

Front 11

List two main components of nucleocapsids

Back 11

two main components of nucleocapsids are the capsid and the nucleic acid

Front 12

What are nonenveloped virus called?

Back 12

Noneveloped viruses are called naked viruses.

Front 13

The placement of viruses into families depends upon which characteristics?

Back 13

The placement of viruses into families depends upon structural features: what their general size and shape are, whether they are naked or enveloped, and if their nucleic acid is DNA or RNA.

Front 14

What part of the envelope comes from the host cell and what part from the virus?

Back 14

The membrane is from the host and the attachment proteins are from the virus.

Front 15

What type of molecule in an enveloped virus is necessary for attachment to the cell?

Back 15

A viral attachment protein protrudes outside of the viral envelope is necessary for attachment to the host cell.

Front 16

Adsorption of the virus to the cell depends upon what specific viral and cellular components?

Back 16

viral attachment protein and a cell receptor

Front 17

What are two types of penetration?

Back 17

Two types of penetration are endocytosis and membrane fusion.

Front 18

Where and how does the process of uncoating take place?

Back 18

Uncoating is the removal of the viral capsid protein by cellular enzymes in the cell cytoplasm.

Front 19

Where does viral translation occur?

Back 19

Viral translation occurs in the host cytoplasm.

Front 20

How does the assembly of intact virions occur?

Back 20

Proteins from the coating bind to each other and to the proper nucleic acid.

Front 21

Describe how the release of virions can occur by cell lysis or budding.

Back 21

A naked virus simply lyses the cell to release virions; an enveloped virus acquires a membrane from the host as it passes through the cell membrane.

Front 22

How many phages or virions can be produced in a single growth cycle?

Back 22

About one hundred phages per bacterium and about three hundred thousand animal virions per animal cell can be produced in a single growth cell cycle.

Front 23

What are the differences between lytic and lysogenic viruses?

Back 23

Lytic viruses always kill the host cell by breaking it open. Lysogenic viruses enter the cell where their DNA integrates into the host cell and becomes part of it; they then divide with the cell. If the host cell becomes sick, lysogenic viruses become lytic and escape the dying cell.

Front 24

What are cytopathic effects?

Back 24

Cytopathic effects result when a viral specimen is placed on human tissue cells in a culture medium. Cytopathic effect refers to visible changes, microscopic or otherwise, in cells resulting from viral infection.

Front 25

What is a plaque?

Back 25

Plaque is a specific type of CPE where cells are killed so that loss of cells gives rise to a hole in the cell layer.

Front 26

How is the inclusion body type of CPE observed?

Back 26

Inclusion bodies are normally seen in the microscope as dark areas of viral material.

Front 27

What are the resulting large cells called when many cells fuse together as a result of viral infection?

Back 27

When many cells fuse together as a result of viral infection, the large cells are called syncytia or giant cells.

Front 28

What changes occur during transformation?

Back 28

In transformation, viruses cause the cells to keep growing uncontrollable and pile up or form a tumor.

Front 29

What do viruses do to the host DNA-synthesizing machinery?

Back 29

Viruses subvert the host cell machinery into making viruses rather than cellular materials.

Front 30

What type of nucleic acid is in a virion?

Back 30

The nucleic acid in a virion is either RNA or DNA, but not both.

Front 31

Why is tumorigenesis only associated with DNA viruses or retroviruses?

Back 31

Tumorigenesis only occurs when a cell's genes are altered to cause uncontrollable cell division. Only DNA can integrate into the cell's chromosome because the chromosome is DNA.