Chapter 19: Viruses Flashcards

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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
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2
Q

Capsid

A
  • Protein shell
  • Encloses a viral genome
  • May be rod-shaped, polyhedral, or more complex in shape
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3
Q

Viral Envelope

A
  • Membrane derived from membranes of the host cell

- Cloaks the capsid and therefore encloses a viral genome

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4
Q

Bacteriophage (Phage)

A

Virus that infects bacteria

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5
Q

Host Range

A

Limited number of species whose cells can be infected by a particular virus

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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

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7
Q

Virulent Phage

A

Phage that replicates only by a lytic cycle

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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)
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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
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10
Q

Temperate Phage

A

Phage that is capable of reproducing by either the lytic or lysogenic cycle

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11
Q

Prophage

A

Phage genome that has been inserted into a specific site on the bacterial chromosome

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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
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13
Q

Reverse Transcriptase

A
  • Enzyme encoded by retroviruses

- Uses RNA as a template for DNA synthesis

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14
Q

Human Immunodeficiency Virus (HIV)

A
  • Infectious agent that causes AIDS

- A retrovirus

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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
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16
Q

Provirus

A

Viral genome permanently inserted into a host genome

17
Q

Conjugation

A
  • In prokaryotes, direct transfer of DNA between two cells that are temporarily joined
  • When the two cells are members of different species, results in horizontal gene transfer
18
Q

Transformation

A

Change in genotype and phenotype due to the assimilation of external DNA by a cell