2026 ACTUAL EXAM
◉ When are Viruses considered to be "alive"? Answer: When they
are inside of a host cell.
When inside, their nucleic acid (ONLY RNA OR DNA) become active.
*Virus replicates
◉ Obligatory Intracellular Parasites Answer: Require livinghost cell
in order to multiply - Such as Viruses.
◉ Defining a Virus Answer: 1) Contains 1 Nucleic Acid (DNA or RNA)
2) Protein coat surrounds the DNA or RNA
3)Multiply within host using host machinery
---because they don't have the ways of making/obtaining their own
nutrients. like ATP or enzymes.
◉ Virus Characteristics Answer: *Some are enclosed by an envelope
which consists of lipids, proteins, carbohydrates
*some have spikes
,*only infect the cells of ONE host.
◉ Host Range Answer: The spectrum of host cells that a virus can
infect.
-invertebrates
-vertebrates
-plants
-protist
-fungi
-bacteria
The virus must be able to attach to a the particular host's cell.
**Host range is determined b specific attachment sites on the host
cell's surface
◉ Bacteriophages Answer: Bacteria that is infected by a virus
◉ How do Viruses attach to a host cell Answer: Through receptors
on the host cell's surface.
There must be an interaction.
,◉ Capsid Answer: Protein coat that surrounds the Nucleic Acid of a
virus. (not the whole virus itself. That's an envelope.)
****Made up of individualized Capsomeres****
*accounts for most of the mass of a viral cell.
◉ Capsomeres Answer: Protein subunits that make up a capsid
(think of tiny balls that come together to make a huge coating
around the Nucleic Acid)
*capsomeres can be made up of multiple types of proteins or one
single type of protein
◉ Envelope Answer: Surrounds the virus as a whole.
*Synonymus to a somatic cell's Plasma Membrane. But around a
virus.
***Composed of proteins, lipids and carbs.
*Could be covered in spikes
, NOT ALL VIRUSES HAVE ENVELOPES
◉ Spikes Answer: Cover the envelope of the cell
Composed of protein and carbohydrates.
-Used for attachment to the host cell
Spikes differ, and can be identified as different virus by the host
body. That's why you can get the flu more than once a year, there's a
change in spikes.
-Can be used for identification for some virsus under microscope.
◉ Helical Capsid Answer: Long rods that are flexible and rigid
These surround the Nucleic Acid.
*Capsids are hollow cylinders surrounding the nucleic acid.
*CAN OR CANNOT HAVE A ENVELOPE.