Lecture 5: viruses pt. 1 Flashcards
What two major things are different about viruses, compared to other microbes?
- Are not cells
- are not living
Viruses are considered _____ _______ parasites.
Obligate Intracellular
How do viruses function outside host cells?
- Outside host cell?
Are inactive outside
- Only active in host cell
What are the components of viruses from outside to inside?
How common are these components?
- Envelope (on some)
- Capsid (on all
- Nucleic Acid (in all)
- 1 or 2 enzymes (sometimes)
Fully formed virus, able to establish infection in host:
Virion
- Viruses that have viral envelopes are called:
- Viruses without envelopes are called:
- Enveloped
- Naked
What are most viral envelopes made from?
The host cell’s membrane.
- What projections do viral envelopes contain on the outside?
- What is their purpose?
- Spikes
- Attachment and Entry
- What is the layer that sourronds the nucleic acids of Viruses?
- What is it made of?
- Capsid
- Capsomeres
What are the 3 types of capsid shapes?
- Helical (rod shaped)
- Icosahedral (geometric)
- Complex
What types of nucleic acids can viruses have?
DNA or RNA (but not both)
What variations can virus genomes come in (5 types)
- Double stranded
- Single stranded
- Segmented (RNA only)
- Positive sense (RNA only)
- Negative sense (RNA only)
What is the life cycle of viruses? (6 steps)
- Attachment
- Entry
- Uncoating
- Replication
- Assembly
- Release
How do viruses attach (enveloped and naked)?
- Enveloped viruses use spikes
- Naked viruses use campsomeres
What is the host range of a virus?
Give the types.
What species/cell type a virus can invade
- Narrow
- Specific cells only
- Moderate
- Specific specie
- Broad
- Can infect many species
Host cells that do not have certain receptor that viruses can infect, it is ____
Resistant
a. What are the types of way a enveloped virus can enter cells?
b. Naked viruses?
a. 1) Fuses with host membrane
2) Endoctosis
b. 1) endocytosis
What do:
1) Early
2) Middle
3) Late genes
do?
1) Take over host cell machinery
2) Replicate viral genome
3) Include capsid proteins
What part of the enveloped virus escapes when entering by endocytosis?
Nucleocapsid
What part of naked viruses escapes when entering by endocytosis?
Nucleic acid
Name the steps that dsDNA goes through when infecting a cell.
- Must enter nucleus
- Makes more dsDNA and mRNA
- mRNA travels to cytoplasm to make viral proteins
- Uses host DNA polymerase (to make more DNA)
What is the difference between how Single Stranded DNA enter/ replicate?
Does the same thing except
must become dsDNA first after entering the nucleus.