VIRUSES CH 7 Flashcards
Identify better terms for viruses rather than alive or dead
Active / Inactive
T/F: Viruses are alive
False
Why cant viruses survive outside of a host cell?
They lack cell machinery
Identify the structures common to all viruses
- Capsid (protein coat)
- Nucleic Acid (DNA OR RNA)
- Spikes (Allow attachment to cell surface)
Identify the structures present in some viruses
- Accessory Proteins (specialized effects within the cell; “nice to have”)
- Envelope (extra outer layer made from OUR cell membrane acquired when they enter the cell to hide from our immune system) (or nuclear membrane as they leave the nucleus)
Identify the following structures; select which are present in all Viruses, AND describe their function
A - Accessory Proteins (specialized effects within the cell; “nice to have”)
B - Envelope (extra outer layer made from OUR cell membrane acquired when they enter the cell to hide from our immune system)
C - Spikes (Allow attachment to cell surface + allows them into the host)*
D - Capsid (Protein Coat)*
E - Nucleic Acid (DNA OR RNA; this is used to make more viruses)*
*Present in all viruses
Identify and describe the different viral shapes
Icosahedral - 3D Hexagon
Helical - Spiral Rods
Complex (bacteriophage) - Head, Tail, + Legs
Identify the viral shape
A - Icosahedral
B - Helical
C - Complex (Bacteriophage) (Only Infect Bacteria)
Enveloped vs Naked Viruses
Enveloped - Contain the host’s phospholipid bilayer;
allows it to go unrecognized by the immune system
Naked - Lack an envelope
Where are spike proteins attached?
On the outermost membrane of the virus
Naked: On the Capsid
Enveloped: On the Envelope
How do viruses leave the cell?
Naked Viruses have spikes on the capsid + must fill the host cell with viral particles to get out; When the cell is entirely filled the host cell breaks apart through lysis
Enveloped Viruses have spikes on the cell membrane + are wrapped as they leave the host cell; this is called budding
T/F: Viruses can be seen with a light microscope
False; they require electron microscopes
Viral Capsids are composed of what biochemical group? What are these individual subunits called
Protein; Capsomeres
What are the three unique forms of viral nucleic acid?
DNA
RNA
Reverse Transcriptase - RNA >DNA
Describe the viral life cycle
APUSAR
Adsorption - Spikes to stick to receptors on host cell
Penetration - Entry into the cell
Uncoating - Break capsid open + release nucleic acid
Synthesis - Form more viral capsids + nucleic acids
Assembly - Use capsids and nucleic acid to form more infectious particles +
Release - Leave to infect more cells
DNA vs RNA Virus
DNA Virus must go to the nucleus to trigger protein formation (DNA > mRNA > Protein)
RNA Virus stays in the cytoplasm (can make proteins within the cytoplasm)
What are the two things we want to know about a virus? Why?
DNA or RNA:
DNA virus goes to the nucleus to be turned into RNA and have an effect as proteins
RNA virus doesn’t need to go to the nucleus and can be translated in the cytoplasm
Naked or Envoloped:
Naked virus has spikes on the capsid and causes lysis to get out of the cell (must fully fill the cell with viral particles)
Enveloped virus sends spikes to the cell membrane and are wrapped around the virus on the envelope as they leave the cell
Define Provirus and Latent Phase
Inserts viral DNA into the host DNA; Can go into a latent phase where the trait is inactive but can be reactivated
Oncogenic Virus
Cancer causing virus
~13% of human cancer is caused by viruses
In Vitro vs In Vivo
They are both processes by which we grow viruses
In Vitro - Cells on a plate
In Vivo - Lab animals and bird eggs
T/F: Viral infections are more common than bacterial infections
True
T/F: Viral mutation rates are low and viruses are easy to track in a population
False; they mutate all the time and are impossible to track in a population
Doctors + Scientists most often rely on _______ to treat or prevent viral infections
Vaccines
Why is it difficult to create antiviral treatments?
Viruses use much of human machinery and therefore makes it difficult to target specific features without harming our own cells
