Plasma membrane comprises mainly proteins embedded in a phospholipid bilayer. Protein molecules occur at places both inside and outer side of the lipid bilayer.

The main arena of various types of activities of a cell is cytoplasm. It forms the living protoplasm of a cell excluding the nucleus. It consists of proteins, fats,carbohydrates, nucleic acids, vitamins, waste metabolites and all organelles.

Mitochondria has its own DNA. It is a structure within cytoplasm of eukaryotic cells that carries out aerobic respiration. It is the site of Kreb’s cycle and ETS. Therefore, it is also called as cell’s energy production site.

Middle lamella is mainly composed of calcium pectate.Calcium pectate is like a glue binding adjacent cells together. So if inadequate calcium is transported during cell formation, tissues become less stable and prone to disintegration.

Stroma in the chloroplasts of higher plant contains light independent reactions enzymes. Within the stroma are stacks of thylakoids, the sub-organelles which are the site of photosynthesis.

The cytoskeleton is made up of three kinds of protein filaments actin filaments (also called microfilaments),intermediate filaments and microtubules whose major constituents are actin and tubulin respectively.

Plasmodesmata are narrow channels that act as inter cellular cytoplasmic bridges to facilitate communication and transport of materials between plant cells. Plasmodesmata are formed during cell division,when traces of the endoplasmic reticulum become caught in the new wall that divides the parent cell.