Viruses: Chp 19

Question 1

capsid

Answer 1

a protein shell that surrounds the genetic material

Question 2

viral envelopes

Answer 2

surrounds the capsid and aids the viruses in infecting their host

Question 3

bacteriophages (phages)

Answer 3

viruses that infect bacterial cells

Question 4

host range

Answer 4

meaning that viruses can only infect a very limited variety of hosts

Question 5

lytic cycle

Answer 5

ends int he death of the host cell by rupturing it (lysis). in this cycle, a bacteriophage injects its DNA into a host cell and takes over the host cell’s machinery to synthesize new copies of the viral DNA as well as protein coats. these self-assemble, and the bacterial cell is lysed, releasing multiple copies of the virus

Question 6

lysogenic cycle

Answer 6

the bacteriophage’s DNA becomes incorporated into the host cell’s DNA and is replicated along with the host cell’s genome. the viral DNA is known as a prophage. under certain conditions, the prophage will enter the lytic cycle.

Question 7

retroviruses

Answer 7

RNA viruses that use the enzyme reverse transcriptase to transcribe DNA from an RNA template. the new DNA permanently integrates into a chromosome in the nucleus of an animal cell. the host transcribes the viral DNA into RNA that may be used to synthesize viral proteins or may be released from the host cell to infect more cells

Question 8

viroids

Answer 8

cicular RNA molecules several hundred nucleotides in length that infect plants

Question 9

prions

Answer 9

misfolded, infections proteins that cause the misfolding of normal proteins that contact in varous animal species