Chapter 9, Problem 44A

Summary Introduction

To explain:

Why incidences of cancer increase with age

Introduction:

A cell grows until it reaches its size limit, then it either stops growing or divides. Most cells undergo division. Cell division helps a cell to reproduce and makes the organism grow and heal certain injuries. A cell cycle has a system of control checkpoints to monitor the cycle and stop it if something goes wrong. Sometimes cells fail to respond to normal cell cycle control mechanisms and this causes cancer.

Answer to Problem 44A

Cancer cells undergo uncontrolled, unrestrained growth and division because their genes have been changed. More than one change is required to change an abnormal cell into a cancer cell. Over time it is possible that there could be many changes in DNA. So there is more chance for a person to develop cancer as he or she ages.

Explanation of Solution

Cancer occurs when the normal cell cycle is disrupted and the cell does not respond to control mechanisms. Cancer is uncontrolled growth and division of cells. These unchecked cancer cells can even kill the organism by crowding out normal cells. The changes occur in regulation of cell growth and division of cancer cells due to mutations or changes in certain segments of DNA. Often the genes are altered due to some environmental factors, age and food habits. As the person ages, more and more changes occur in DNA. With the accumulation of these changes, an aged person might develop cancer. So there is an increased chance of cancer with age.