A gene is a basic unit of heredity and a sequence of nucleotides in DNA that encodes the synthesis of a gene product, either RNA or protein. For example, if both of your parents have green eyes, you might inherit the trait for green eyes from them.
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Parasites are those organisms which obtain their nutrition from other living organisms, whereas saprophytes obtain their nutrition from the dead decaying organic
When a drug binds to a receptor in the body , the receptor is activated or inactivated.
Molecules such as hormones, drugs or neurotransmitters that bind to a receptor are called ligands. The binding can be specific and reversible. A ligand may activate or inactivate the receptor; activation may increase or decrease a particular cell function. Each ligand may interact with multiple receptor subtypes.
