Chapter 19: Viruses Flashcards
1
Q
Virus
A
- Infectious particle incapable of replicating outside of a cell
- Consists of an RNA or DNA genome surrounded by a protein coat (capside) and (for some) a membranous envelope
2
Q
Capsid
A
- Protein shell
- Encloses a viral genome
- May be rod-shaped, polyhedral, or more complex in shape
3
Q
Viral Envelope
A
- Membrane derived from membranes of the host cell
- Cloaks the capsid and therefore encloses a viral genome
4
Q
Bacteriophage (Phage)
A
Virus that infects bacteria
5
Q
Host Range
A
Limited number of species whose cells can be infected by a particular virus
6
Q
Lytic Cycle
A
- Type of phage replicative cycle
- Results in a release of new phages by lysis (and death) of the host cell
7
Q
Virulent Phage
A
Phage that replicates only by a lytic cycle
8
Q
Restriction Enzyme
A
- Endonuclease (type of enzyme)
- Recognizes and cuts DNA molecules foreign to a bacterium (such as phage genomes)
- Cuts at specific nucleotide sequences (restriction sites)
9
Q
Lysogenic Cycle
A
- Type of phage replicative cycle
- Viral genome becomes incorporated into the bacterial host chromosome as a prophage, replicated along with the chromosome, and doesn’t kill the host
10
Q
Temperate Phage
A
Phage that is capable of reproducing by either the lytic or lysogenic cycle
11
Q
Prophage
A
Phage genome that has been inserted into a specific site on the bacterial chromosome
12
Q
Retrovirus
A
- RNA virus
- Replicates by transcribing its RNA into DNA and then inserting the DNA into a cellular chromosome
- Important class of cancer-causing viruses
- High mutation rate
13
Q
Reverse Transcriptase
A
- Enzyme encoded by retroviruses
- Uses RNA as a template for DNA synthesis
14
Q
Human Immunodeficiency Virus (HIV)
A
- Infectious agent that causes AIDS
- A retrovirus
15
Q
AIDS (Acquired Immune Deficiency Syndrome)
A
- Symptoms and signs present during the late stages of HIV infection
- Defined by a specified reduction in the number of T cells and the appearance of characteristic secondary infections
