Question 1

What is a virus?

Accepted Answer

An infectious pathogen that can only replicate inside an organism's living cells

Question 2

Why are viruses dependent on their hosts?

Accepted Answer

They do not contain enzymes for metabolism nor ribosomes for protein synthesis, so they must rely on their host for these functions

(takes over its host cell's machinery and uses that to produce what it needs to survive)

Question 3

What is a capsid?

Accepted Answer

A protein shell that surrounds a virus, protecting the viral genome from the environment

Question 4

What is a viral envelope?

Accepted Answer

An outermost layer in many viruses that surrounds the capsid, both protecting the virus and also helping it to attach to cells it prefers to infect

(not all viruses have a viral envelope)

Question 5

What is a virus's host range?

Accepted Answer

The range of cells that the virus likes to infect

(HIV infects T cells; bacteriophages infect bacteria)

Question 6

What is a retrovirus?

Accepted Answer

Type of virus that inserts a copy of its RNA genome into the DNA of the host cell

(contains reverse transcriptase; HIV is a retrovirus)

Question 7

What is reverse transcriptase?

Accepted Answer

An enzyme that retroviruses use to "reverse transcribe" its RNA into DNA

The infected cell then uses this new DNA instead of its original DNA, causing it to create offspring for the virus

Question 8

What is lytic cycle?

Accepted Answer

One cycle of viral reproduction, where the infected cell produces many viral offspring and dies in the process of releasing them

(other cycle is the lysogenic cycle, which doesn't kill the cell immediately/directly)

Question 9

What is the lysogenic cycle?

Accepted Answer

One cycle of viral reproduction, where the infected cell incorporates its DNA into the infected cell's DNA, spreading itself each time the cell divides

(creates a provirus when its DNA is incorporated into the infected cell's; can sometimes enter the lytic cycle)

Question 10

What is a provirus?

Accepted Answer

A virus genome that is incorporated into the host cell's DNA

(created during the lysogenic cycle)

Question 11

What are viroids?

Accepted Answer

Small infectuous pathogens that infect plants

(incredibly small; only a few hundred nucleotides in length, with less than 10,000 atoms)

Question 12

What are prions?

Accepted Answer

Misfolded proteins that can convert normal proteins into other misfolded proteins

(mad cow disease is a prion)

Virus Genetics, AP Biology Flashcards