bio test virus

Question 1

7. Are viruses living? What are the characteristics of life for viruses?

Answer 1

No.

Living:
- use nucleic acids
- store genetic info
- adapt to changing conditions

Non-living:
- not made of cells
- cannot reproduce by themselves
- do not produce energy or waste

Question 2

7. What are the structures and functions of viruses?

Answer 2

1. Nucleic Acid - DNA/RNA
2. Capsid - Protective coat
3. Envelope - Membrane that originates from the host

Question 3

7. What are the three hypothesis on the origin of viruses?

Answer 3

1. Originated as small infectious cells that lost their cytoplasm and ability to reproduce outside of a host.
2. Originated as “escaped” fragments of DNA or RNA molecules that once formed part of living cells.
3. Viruses are ancient- existed even before cells.

Question 4

7. How are viruses classified?

Answer 4

Genetic material, envelope, size, shape

Question 5

7. How is a virus injected?

Answer 5

Bacteriophages: Viruses that specialize in infecting bacteria.

Has:
Capsid, DNA genome, tail to inject DNA into host bacterial cell.

Question 6

7. Name and describe all of the steps in the reproduction of a virus? (both stages)

Answer 6

Lysogenic:
1. Attachment and entry
2. provirus stage
3. mitosis
4. either repeat or enter the Lytic phase

Lytic:
1. Attachment and entry
2. Provirus stage
3. DNA replication (using host proteins)
4. Fabrication
5. Assembly
6. Lysis
7. Repeat

Question 7

7. Are viruses caused by bacteria? What drugs work against them, and what do these drugs do?

Answer 7

No.

Anti-viral drugs:
- Block receptors
- Boost immune system
- Lower viral load in the body (amount of active viruses)

Question 8

7. How can viruses be spread?

Answer 8

Bites, fluids, direct contact, airborne

Question 9

7. What are vaccines? What viruses have they erased? What are some challenges?

Answer 9

Vaccines are mixtures including a weakened form of the virus. They create a chemical memory which the cell remembers when it encounters a virus, triggering an immune response. Erased polio, smallpox, HPV. Some viruses don’t have vaccines and viruses change constantly.

Question 10

7. What are some other non-living genetic particles?

Answer 10

1. Viroid’s: small infectious particles mad of RNA.
   - infect mostly plants
   - smaller than viruses
2. Prions: small infectious proteins that causes damage to nerve cells
   - can cause other misfolded proteins to turn into prions.