AP Biology Chapter 19.1-19.2
Which statements about viruses are true?
- Enveloped viruses bud from the host cell. - The capsid enters the host cell if the virus is enveloped. - HIV contains reverse transcriptase. - A retrovirus contains RNA.
Which of these binds to receptor molecules on the host cell membrane?
A
Which of the following events stimulates the production of viral particles in a host cell?
Activation of the host cell by cytokines, growth factors, or antigens.
Why are viruses called obligate intracellular parasites?
All of the above. - They must use a host cell's nucleotides for transcription and replication. - They must use a host cell's ribosomes to synthesize proteins. - They must use a host cell's amino acids to synthesize proteins. - They must use a host cell's metabolic enzymes and pathways to obtain energy.
Which of these is reverse transcriptase?
C
Which of these is the viral genome?
E
True or false? The human immunodeficiency virus (HIV) uses reverse transcriptase to make double-stranded RNA copies of its DNA genome.
False
How does HIV cause disease?
HIV kills cells that defend the body against disease.
Which enzyme inserts viral DNA into the host's chromosomal DNA?
Integrase
What is the function of reverse transcriptase?
It catalyzes the formation of DNA from an RNA template.
What happens first when a phage infects a bacterial cell and is going to enter a lysogenic cycle?
Linear DNA circularizes.
Which replicative cycle describes a virus that can integrate its genome into the host cell's genome?
Lysogenic
How does HIV bind to a host cell?
The viral envelope proteins interact with CD4 and a co-receptor on the cell membrane.
Which of the following supports the argument that viruses are nonliving?
They are not cellular.
How do enveloped viruses differ from nonenveloped viruses?
They have a membrane-like outer covering.
Why are retroviruses considered a special class of viruses?
They transcribe RNA to DNA using reverse transcriptase.
The nucleic acid of a virus particle is enclosed in a protein coat. What is it called?
capsid
The pointer is indicating the virus's _____.
genome
What is the source of a viral envelope?
host cell membrane
Cycle A is the _____ cycle and cycle B is the _____ cycle.
lytic ... lysogenic
Classify each phrase as applying to the lytic cycle, the lysogenic cycle, or both types of reproductive cycles of phages. Drag the descriptions into the appropriate bins.
lytic cycle: - the cell is lysed (broken open) - new phages are assembled from viral DNA and proteins - the host is destroyed lysogenic cycle: - the cell reproduces normally - the viral DNA integrates into the chromosome of the host cell both cycles: - viral genes are replicated
What do we call a virus that attacks a bacterium?
phage
Double-stranded viral DNA is incorporated into a host cell as a _____
provirus
What enzyme allows a retrovirus to make DNA from an RNA template?
reverse transcriptase
HIV uses which of the following processes to synthesize a DNA strand using its RNA genome as a template?
reverse transcription
The lytic cycle of bacteriophage infection ends with the _____.
rupture of the bacterium
The genetic material of HIV consists of _____.
single-stranded RNA
As a result of the lytic cycle, _____.
the host cell's DNA is destroyed
Viral DNA makes mRNA by the process of _____.
transcription
What is the most effective way to stop viral infections?
vaccines
In the lysogenic cycle _____.
viral DNA is replicated along with host DNA
The pointer is indicating the _____.
viral protein coat
Sort the items according to whether they may be found only in free virus particles, only in uninfected host cells, or in both viruses and host cells. Drag each item to the appropriate bin.
viruses only: - capsid - capsomere(core protein) - envelope with glycoproteins host cell only: - ribosome both: - DNA - RNA - protein
