chapter 19 bio 150 mastering biology

Why is combination drug therapy for HIV/AIDS less likely to lead to resistance than single drug therapy?

The likelihood of one virus spontaneously mutating to be resistant to several different drugs at the same time is extremely small.

In electron micrographs of HSV infection, it can be seen that the intact virus initially reacts with cell-surface proteoglycans, then with specific receptors. This is later followed by viral capsids docking with nuclear pores. Afterward, the capsids go from being full to being "empty." what statements best fits these observations?

The viral envelope mediates entry into the cell, the capsid mediates entry into the nuclear membrane, and the genome is all that enters the nucleus

How does HIV bind to a host cell?

The viral envelope proteins interact with CD4 and a co-receptor on the cell membrane.

The nucleic acid of a virus particle is enclosed in a protein coat. What is it called?

capsid

Which of the following is NOT a characteristic of living things?

creating energy

what event stimulates the production of viral particles in a host cell?

Activation of the host cell by cytokines, growth factors, or antigens.

what statement best reflects what we know about how the flu virus moves between species?

An animal such as a pig is infected with more than one virus, genetic recombination occurs, the new virus mutates, the virus is passed to a new species such as a bird, and the virus mutates again and can now be transmitted to humans.

How does HIV cause disease?

HIV kills cells that defend the body against disease.

What enzyme inserts viral DNA into the host's chromosomal DNA?

Integrase

What do we call a virus that attacks a bacterium?

Phage

what statements supports the argument that viruses are nonliving?

They do not carry out metabolic processes.

what statement correctly describes vaccines and how they help prevent viral infection?

Vaccines are inactive versions of a virus that stimulate an immune reaction in a person

what description correctly identifies the main structural differences between viruses with envelopes and viruses without envelopes?

Viruses with envelopes have a phospholipid membrane outside their capsid, whereas viruses without envelopes do not have a phospholipid membrane.

what can be found in bacteria, but not viruses?

a cell membrane

Homeostasis is a living organism's

ability to maintain constant internal conditions even when environmental conditions change.

Which of the three types of viruses shown would you expect to include glycoproteins?

reminder: go to your book and study this

True or false? The human immunodeficiency virus (HIV) uses reverse transcriptase to make double-stranded RNA copies of its DNA genome

false A retrovirus such as HIV has an RNA genome and uses reverse transcriptase to make double-stranded DNA copies of the genome, which can then be integrated into the host cell's genome.

What are prions?

misfolded versions of normal protein that can cause disease

Which of the three types of viruses shown in the figure would you expect to include a capsid(s)?

reminder: go to your book and study this

What replicative cycle describes a virus that can integrate its genome into the host cell's genome?

the lysogenic cycle

Viruses are not alive because

they are not made of cells and require a host cell for reproduction.

In the lysogenic cycle _____.

viral DNA is replicated along with host DNA