Download Chapter 2A: Viruses and Bacteria

Chapter 2A: Viruses and Bacteria
2-1: VIRUSES
I. What is a virus?
Virus: small, nonliving particle that invades and then reproduces inside a living cell
Viruses—Living or Nonliving?
Remember—all living things have most of the following characteristics. Do viruses
have these characteristics?
1. Made up of cells no
2. Contain similar chemicals no
3. Grow and develop no
4. Use energy no
5. Respond to surroundings no
6. Reproduce ONLY when inside a living cell
Host: living thing that provides a source of energy for a virus or organism
Parasite: organism that lives in or on a host and causes harm
--Almost all viruses act like parasites because they must be inside a living cell to
reproduce AND because they destroy the cells in which they multiply.
II. Naming viruses
--Viruses are NOT named by binomial nomenclature because they are not living.
Instead they are named by: disease caused (ex: polio), infected organism (ex: tomato
mosaic virus), place found (ex: Ebola), or the discovering scientist (ex: Epstein-Barr
virus)
III. The Shapes and Sizes of Viruses
--Viruses vary in shape: round, rod-shaped, bricklike, robotlike, etc.
--An example of a robotlike virus is the bacteriophage: virus that infects bacteria
(“bacteria eater”)
--Viruses vary in size, but all are smaller than cells, can ONLY be seen with powerful
microscopes, and are measured in nanometers (nm).
IV: Structure of Viruses
Two basic parts:
1. Outer protective coat
-made up of unique proteins
-proteins allow it to attach only to certain cells
2. Inner core made up of genetic material
-contains the instructions for making new viruses
V: How Viruses Multiply
Active Virus:
-after entering cell, IMMEDIATELY goes into action
-virus’s genetic material takes over cell’s function
1. Virus attaches to cell
2. Injects genetic material
3. Cell produces virus’s proteins and genetic material
4. Parts assemble to make new viruses
5. Keeps copying
6. Cell bursts when too full and releases new viruses
Hidden Virus:
-doesn’t take action immediately
1. Virus attaches to cell
2. Injects genetic material
3. Virus’s genetic material becomes part of cell’s genetic material
4. Virus becomes active and takes over cell’s function
5. Cell produces virus’s proteins and genetic material
6. Parts assemble to make new viruses
7. Keeps copying
8. Cell bursts when too full and releases new viruses
EXAMPLE: cold sore
Remember: Some viruses are good. They are being used in gene
therapy.
Chapter 2: VIRUSES
I. What is a virus?
Virus:
___________________________________________________________________________
_______________________________________________________________________
Viruses—Living or Nonliving?
Remember—all living things have most of the following characteristics. Do viruses
have these characteristics?
1. Made up of cells ________
2. Grow and develop ________
3. Use energy ________
4. Respond to surroundings ________
5. Reproduce _________________________________________
___________: living thing that provides a source of energy for a virus or organism
__________________: organism that lives in or on a host and causes harm
--Almost all viruses act like parasites because they must be inside a living cell to
reproduce AND because they _____________________________________________
_________________________________________________.
--Viruses vary in size, but all are _______________________________________.
II: How Viruses Multiply
Active Virus:
EXAMPLE:
-after entering cell, IMMEDIATELY goes into action
-virus’s genetic material takes over cell’s function
1. Virus attaches to cell
2.
3. Cell produces virus’s proteins and genetic material
4.
5. Cell bursts when too full and releases new viruses
Hidden (Latent) Virus: EXAMPLE:
-doesn’t take action immediately
1.
2. Injects genetic material
3.
4.
5. Cell produces virus’s proteins and genetic material
6. Parts assemble to make new viruses
7. Keeps copying
8.
III. Virus Effects on Organisms
--Most viruses attach to __________kind of host cell.
--Viruses are transferred by
--A virus that enters bacteria is called a _______________________________________.
IV. Fighting Viruses
--A vaccine is ______________________________________________________________
__________________________________________________________________________.
--The first vaccine was made in 1796 by ______________________. It was created to
fight ____________________________.
--Ways to treat a virus include:
V. Research with Viruses
--Viruses can be good. They are being used in _________________________________.
--Some day, they may cure people with _________________________________ or
_____________________________.