abnormal gene

Mutation is defined as a chemical change in the DNA structure of a gene. A difference of a single base in the DNA molecule or a single error in the reading of the code can cause a change in the amino acid sequence which leads to mutation. The chemical substances that induce mutations are ..

The first and only atomic bombs were used in war was in 1945 when Hiroshima and Nagasaki were devastated. Widespread destruction and damage were produced immediately by the blast. Some of the damage caused by the emitted radiation became evident within days, but some did not become evident until y..

These disorders are caused by genes present on the sex chromosomes. The abnormal disorders express more commonly in males than females. Some common examples are colour blindness, haemophilia and congenital night blindness. fig. 20.5 Colour Blindn..

>Any change in the expression of a gene follows an interaction between nucleus, cytoplasm and environment. Cancer is a differentiation related disease. In cancer, the cells continue to divide due to lack of the property of contact inhibition. Cancer is caused by activation of genes..

Growth and division of normal cells are regulated by control mechanisms. One such control mechanism is contact inhibition. As a result of multiplication, the cells become crowded and come in contact with one another. This surface contact checks movement and division of cells. Therefore, the ge..

Cancer is characterised by uncontrolled growth and division of certain body tissues, so forming a tumour. It is one of the major killers today. Normally cell division is a regulated process. Mature cells are replaced by new cells produced by cell division and differentiation. Due to altered ..