Pathogens+DB

1. What is a pathogen? A pathogen is a bacteria or virus that can cause infectious diseases.

2. What are the body's three lines of defense against pathogens? Three lines of defense include; skin and mucus membranes around body cavities, white blood cells that prevent infection, and specific defenses in the body for the particular disease.



3. Write a one paragraph summary of bacteria. Bacteria are pathogens that are single-celled and don't have a nucleus. Their DNA is instead stored in a chromosome located in the center of the cell. Bacteria can have a rod shape in which case it is called a bacillus, a spherical shape (a coccus), or a curved shape (a spirillum). Bacteria are metabollically independant cells and have the ability to reporduce very quickly via binary fission.



4. Write a one paragraph summary of viruses. Viruses are pathogens that are nearly four time smaller than bacterium. They are not made up of cells at all, but have a protein shell and a nucleic acid center. Viruses are neither alive nor nonliving and function by taking over a host cell an injecting their own DNA causing the cell to change and produce more viruses.

5. What is an emerging virus? An emerging virus is an apparently "new" virus that the body's defense system doesn't recognize. It may be transferred to humans by animals or may spread due to people traveling frequently.

IMMUNE SYSTEM 6. What is an antibody? What do they do? Antibodies are cells that signal for white blood cells to come and protect against disease.

7. What is B Cell? A B cell is a part of the specific defense of the body. B cells turn into plasma cells and memory cells when activated.

8. What is a Cytotoxic T Cell? A cytotoxic T cell kills virus-infected cells and cancer cells.

9. What is a Helper T Cell? A helper T-cell regulates immunity.

10. What is an antigen? How does the body respond to an antigen? An antigen is a cell that the body recognizes as foreign. It is a "non self" cell. The body responds to an antigen with defense antibodies.