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       Gene is the hereditary unit which is responsible for the inheritance of characters from one generation to other. Actually gene is a part of DNA and is made up of nucleotides. The term gene was first of all coined by scientist Johanssen in 1909.

Strucutre of Genes        Genes are responsible for our characteristics i.e. all our characters such as our complexion, appearance, height, colour of hair, colour of eyes, shape of nose etc. are determined by genes. Genes are located on the chromosomes which are present in the nucleus of every cell. Chemically genes contain DNA as primary component. The total number of genes in human beings is 3, 00,000 and the number of genes present on one set of chromosomes range in between 10,000 to 15,000. From the above discussion we can now define the gene as gene is a hereditary unit present on a chromosome which can be transmitted from one generation to another.

Types of Genes

Genes can be classified into two types:

1. Autosomal Genes

       The genes which are present on autosomes are known as autosomal genes.

2. Sex Linked Genes

       The genes which are present on sex chromosomes are called sex linked genes.

Test Your Understanding and Answer These Questions:

  1. Define genes.
  2. Explain various types of genes.

  3. Where are the genes located?

  4. What is importance of genes in living organisms?

  5. What is chemical nature of genes?

  6. How many genes have been estimated to be present in one human chromosome?