Cell Biology

Cell Biology or Cytology is a branch of Biology that deals with the study of cell.

Cell:

A cell is the smallest mass of cytoplasm bound by a cell membrane. It is the building block of all organisms. A cell is capable of sustaining all the life processes within it. A cell is composed of

• Cell wall and Plasma membrane
• Cytoplasm
• Nucleus

Cell wall and Cell Membrane:

Cell walls and cell membranes are semi permeable boundary walls of the cell. Cell walls are present in plant cells only. Animal cells are bound by cell membranes only.

Cytoplasm:

Cytoplasm is composed of a jelly like substance called cytoplasmic matrix and fills the space between cell membrane and nucleus. Many tiny structures of different shapes, sizes and functions are embedded in cytoplasmic matrix, which are called cell organelles. Some important cell organelles are

• Endoplasmic reticulum:

  It is a network of membrane bound sacs and tubules.

• Golgi Apparatus:

  It is composed of stacked sac like structures called cisterns. Ribosomes- These are minute spherical structures found attached to endoplasmic reticulum.

• Lysosomes:

  These are mall sac like structures..They are also called "suicide bags".

• Mitochondria:

  These are double layered membrane bound structures which act as powerhouse of the cell.

• Plastids:

  plastids are found only in plant cells. There are two types of plastids :Chromoplasts (coloured plastids) and Leucoplasts (Colourless plastids):

• Vacuoles:

  Vacuoles are bag like structures of various sizes. They are larger in plant cells than those in animal cells.

Nucleus:

Nucleus is a spherical body, which is composed of a) nuclear membrane, b) nucleoplasm and chromosomes and c) nucleolus. Chromosomes are responsible for transfer of genetic materials from one generation to another.

Cell Division:

A cell can reproduce more cells by the process of cell division.