Question

i need an informative speech on Cancer with its

topic

general purpose

specific purpose

central idea statement

Answer 1

When normal cells have lost the usual control over their division, differentiation and apoptosis they become tumor cells. Tumor or neoplasm (any abnormal proliferation of cells) may be of two types: Benign tumor and Malignant tumor. The term Cancer mainly refers to malignant tumors which invade surrounding normal tissues (invasiveness) and spread throughout the body through circulatory or lymphatic systems (called metastasis).

The transition from a normal to a transformed state is a multistep process involving genetic as well as epigenetic changes and selection of cells with the progressively increasing capacity for proliferation, invasion and metastasis.

Cancer cells typically display several abnormal properties as compared to normal cells that provide a description of malignancy at the cellular level:

• Density dependent inhibition
• Contact inhibition
• Immortalization
• Invasiveness and metastasis
• Angiogenesis
• Loss of anchorage dependence
• Lower growth factor requirements
• Fail to undergo apoptosis.

All genes whose genetic and epigenetic changes contribute to the causation of cancer is described as cancer-critical genes. The genes may be involved in cell cycle progression (eg. Rb, myc), differentiation process (eg. Hh, Apc), DNA repair and cell death.

These genes can be grouped into two classes: proto-oncogenes and tumor suppressor genes.

Genes for which a gain of function mutation drives a cell towards cancer are called proto-oncogenes whereas genes for which a loss of function mutation creates the cancer are called tumor suppressor genes.

Today more than 40 different human proto-oncogenes are known. Several types of genetic and epigenetic changes convert these proto-oncogenes into oncogenes. Oncogenes arise as a result of changes that increase the expression level or activity of a proto-oncogene. Underlying mechanisms associated with proto-oncogenes activation include : point mutation, chromosomal translocation, insertional inactivation and gene amplification.

p53 is a well studied tumor suppressor gene that encodes a polypeptide which acts as a transription factor. Mutations in the p53 gene are associated with more than 50 percent of human cancers.

Agents that initiate or promote tumir formation are called carcinogens. Three classes of carcinogens agents are known: Radiations (like UV radiation and gamma ray), chemicals (benzopyrene and benzene) and biological (oncovirus) agents. The ability of chemical and physical carcinogens to induce cancer can be accounted for by the DNA damage that they cause and by the errors introduced into DNA during the cells' efforts to repair the damage.