Viruses - Ch. 21

Question 1

What are the seven characteristics of life?

Answer 1

have organization, made from one or more cells, go through metabolic activity, maintain homeostasis, reproduce, grow, and evolve

Question 2

Differences between bacteria and viruses

Answer 2

bacteria is prokaryotic and viruses are non-living
bacteria are free-living and viruses are intracellular parasite
bacteria are relatively large and viruses are 1/1000 of bacteria size
bacteria is stopped by antibiotics and viruses are stopped by anti-virals and vaccines

Question 3

What are the components of viruses

Answer 3

they have a nucleic acid, either RNA or DNA, they are double or single stranded, capsid (protein shell), and some have envelopes around them.

Question 4

How do viruses enter the host?

Answer 4

attach to host cell cell membrane receptors through capsid proteins or glycoproteins on viral envelopes. reproduce easily within host cell and mutate easily.

Question 5

lytic cycle

Answer 5

use host machinery to replicate, assemble, and release copies of the virus.

Question 6

virulent phages

Answer 6

cells die through lysis or apoptosis

Question 7

lysogenic cycle

Answer 7

DNA incorporated into host DNA and replicated along with it. Not all go through lysogenic cycle but all go through lytic

Question 8

Bacteriophage

Answer 8

viruses that attach bacterial cells
lytic cycle:
1. attachment
2. entry of phage DNA and degradation of host DNA
3. synthesis of viral genomes and proteins
4. assembly
5. release

Question 9

temperate phage

Answer 9

uses both methods of replication

Question 10

animal viruses

Answer 10

have a membrane envelope, host membrane forms around existing virus, difficult for host immune system to detect virus

Question 11

retrovirus

Answer 11

RNA viruses that uses reverse transcriptase
newly made viral DNA is inserted into chromosomes of the host
host transcribes provirus to make new virus parts

Question 12

example of a retrovirus

Answer 12

HIV, infects white blood cells (helper T)

Question 13

vaccine

Answer 13

weakened virus or part of pathogen that triggers immune system response to prevent infection

Question 14

anti-viral drugs

Answer 14

block viral reproduction after infection

Question 15

viroids

Answer 15

small, circular RNA molecules that infect plants
causes errors in regulatory systems that control plant growth
no protein, nucleic acid

Question 16

prions

Answer 16

misfolded, infectious proteins that cause misfolding of normal proteins
no nucleic acid, just protein

Question 17

prions course

Answer 17

prions act slowly, with an incubation period of atleast 10 years before symptoms even occur. virtually indestructible with no known cure