1. Viruses

2. Virus:
Segments of nucleic acid (DNA OR RNA) within a protein coat (noncellular);
NONLIVING;
much smaller then prokaryotes
Must reproduce within a host cell
Many viruses are host specific

3. Viral structure Capsid- protein coat of virus
Envelope- a membrane layer around the capsid in some viruses.

4. Bacteriophage
A virus that infects bacteria

5. Viral reproduction:
Viruses rely on cells to replicate them and use either the lytic cycle or lysogenic cycle to replicate.

6. Lytic cycle
1. virus attaches to a cell and injects its genetic material.
2. The cell makes new viral parts.
3. The cell breaks down and releases viruses.
Viruses like the flu and cold do this

7. Lysogenic cycle 1. Virus attaches to cell and injects DNA
2. Viral DNA integrates with host DNA
3. The host cell divides normally and when it does, so does the viral DNA
4. After some time, the virus enters the lytic cycle and the cell will be destroyed when new viral parts are assembled and made
Ex- HIV, herpes

9. Retrovirus: Has RNA as it’s genetic material; ex- HIV which cause AIDS
Prions: a disease causing piece of protein with no nucleic acid- ex- mad cow disease
Viroids: a disease causing strand of RNA with no capsid

10. Diseases caused by viruses

11. Modes of transmission Contact with bodily fluid Contact with warts
Contaminated Food
Contaminated Water
Mosquito bite

12. Protection from viral diseases
Prevention- hand washing, don’t drink after people, etc
Vaccines