Question

Write short notes on the following
(a) Cytoplasm
(b) Nucleus of a cell

Answer 1

Cell is the basic unit of life which consists of cytoplasm, cell membrane, cell wall (in case of the plant), cytoplasm, cell organelles and nucleus. The cytoplasm is the semi-fluid part of a cell and the nucleus is the control point of the cell.

Complete step by step answer:
(a) Cytoplasm: It is the semi-fluid part of the cell whose main constituent is water and it is the site for a maximum reaction. It is surrounded by a cell membrane. Various cell organelles like mitochondria, ribosomes, Golgi apparatus, endoplasmic reticulum etc. are suspended in it. The cytoplasm is always in the flowing state called cytoplasmic streaming or cyclosis. This phenomenon is absent in prokaryotic cells and present in a eukaryotic cell.
(b) Nucleus of a cell: It is the dense structure present in the cell, it also acts as the information centre of the cell. It is surrounded by a nuclear membrane. It contains chromosomes that contain genetic material, i.e. DNA which is transferred from one generation to another generation. Its number can vary from one to many per cell.
For multinucleate condition, there are two kinds of cell:
A) Syncytium cell: it is the multinucleate condition in which multiple nuclei are formed by the aggregation of cells and then followed by the dissolution of cell membrane between them.
B) Coenocytic cell: in this condition , multiple nuclei is formed due to the division of the nucleus without undergoing the cell division.

Note: The nucleus was the first cell organelle to be discovered by the scientists. It takes about 10 percent of the cell volume. A human nucleus consists of about 10 feet long DNA molecule tightly packed by certain proteins. On the other hand, the cell was first discovered by Robert Hooke in 1665. They are of two types; prokaryotic cells and eukaryotic cells. Prokaryotic cells are the primitive cells, whereas eukaryotic cells are the specialized modern cells.