Chapter 2: The Structure of Viruses and Cells

VIRUSES

• Virus- piece of hereditary material covered by protein that infects & reproduces ONLY inside a living cell– The living cell is called a host cell

VACCINES

Vaccine- made from damaged virus particles that can’t cause disease anymore

Edward Jenner (1796)- Developed the first vaccine for smallpox

Latent vs. Active Viruses

• Latent- appear to “hide” inside host cell for a certain period of time, until there is a stimulus– Herpes, mononucleosis, HIV, invading flu, cancer

• Active- exhibiting symptoms for the disease– AIDS, flu with symptoms

Viral DiseasesDisease Affected Body Part Vaccine

AIDS Immune system no

Chicken Pox Skin yes

Common Cold Respiratory System no

Influenza (flu) Respiratory System yes

HPV Cervix (female) yes

Herpes Skin no

Pneumonia Respiratory System yes

Smallpox Skin yes

HIV/AIDS

HIV = human immunodeficiency virusAIDS = acquired immune deficiency syndrome

HIV is the virus that causes the disease AIDS.

HIV is spread through:sexual contact, sharing needles with an infected person, blood & body fluids, infected mother to unborn child

How does temperature affect viruses?Graphing Activity page 37

X axis = Temperature (celsius)

Y axis = Viruses (millions)

36.9 1.0

37.2 1.0

37.5 0.5

37.8 0.25

38.3 0.10

38.9 0.05

Things to put in your line graph

1. Title: The Impact of Temperature on the Number of Viruses2. Label the x and y axis (x is temperature (C); y is number of

viruses (millions) ).3. Intervals for y, each line is 0.05, but just label 0.1, 0.2, etc.

(skip two boxes, one line break)4. Break on x axis5. Use whole numbers on x axis, start at 36 and skip 5 boxes

b/w each number.6. Put your name in upper right hand corner, include t-chart,

degrees C on points (dots), questions answered on back.

Answer the following questions on the back of your graph.

1. What happens to the number of viruses as the temperature increases?

2. Why do we get a fever when a virus is attacking our body?

3. What would happen if one had a virus in his/her body, but his/her immune system did not respond?

Cells• Cell: The smallest unit of life. The smallest

unit of an organism that can perform all life functions.

(grow, reproduce, attain energy and get rid of waste, adaptation)

Cell Theory

1. All organisms are made up of one or more cells.

2. Cells are the basic units of structure and function in all organisms.

3. All cells come from cells that already exist.

Discovering Cells• Robert Hooke first observed cells. (1665) He

viewed a piece of cork under a microscope and saw small boxes that looked like cells in a monastery.

You see this He drew this

Microscopes

• Simple (1 lens) – Anton van Leeuwenhoek

• Complex (2 lenses)– Zacharias Janssen

Compound Light Microscope