Question

What is the difference between an allergen and and a pathogen?

Discuss the stages of cancer. Begin with why a cancer may begin and what a cancer cell is (why does it continue to multiply). Take it through the stages to when it become malignant and what that means.

What is HIV? Include if it is virus or bacteria and what disease often develops due to this infection.

An autoimmune disease is dangerous because the immune cells attack__________________

Answer 1

An allergen is any substance on contact, that is recognized by the immune system and causes an allergic reaction. Dust, pollen and pet dander are all common allergens. A pathogen or infectious agent is a biological agent that causes disease or illness to its host. Bacteria, viruses etc are common pathogens. The main difference is Allergens only affect people who have sensitivities to them, whereas anyone can get sick after contact with a pathogen.

Normal cells on exposure to mutagens such as radiation, oxidative free radicals, reactive chemicals etc leads to mutations of genetic material or DNA. This leads to the production of oncogenes and a decrease in the production of tumor suppressing molecules such as p53 in the cell. Some mutations in the genes passed to next generation also. As a result cells resist apoptosis and undergoes clonal growth. Finally uncontrolled growth of abnormal cells resulted and it is called a cancerous tissue.

Some cancer cells can move into the bloodstream or lymph nodes and can invade near by tissues and then its called a malignant cancer.

HIV (Human Immunodeficiency virus) is a virus belonging to retroviridae family and lentivirus genus. It can infect humans and cause a disease called acquired immunodeficiency syndrome (AIDS).  AIDS is a condition in which progressive failure of the immune system leads to life-threatening opportunistic infections and cancers.

An autoimmune disease is a condition in which an abnormal immune response generated against host normal cells. Antibodies are produced against specific host cells and these antibodies kills normal host cells. For example in graves disease antibodies are produced against thyroid cells.