Cell and its Types

                                          Cell and its Types

Cell: Cell is the structural and functional unit of all living organisms. The organisms which are made up of a single cell is called as the Unicellular  while the organisms made up of multiple cell like human being , cow and buffalo are called as the multi-cellular cell. Cell was discovered by the Robert Hooke, an English scientist in 1665.

All cells contain three basic structures:

• Plasma membrane: It is made up of lipids and proteins and help in the transportation of nutrients form the external environment to inside the cell.
• Cytoplasm: It is a fluid like substance that contains Cytosol and cell organelles such as mitochondria, chloroplast etc.
• Nucleus : It is the main parts of the nucleus as it contains the genetic information as DNA present in it. Fluid inside the nucleus is Nucleoplasm.

*Protoplasm is the combined form of the Nucleoplasm and Cytoplasm.

*The Non-living things inside the cell are called as the Deutoplasm.

Cell Theory:

Cell theory is given by M Schleiden a German Botanist and T Schwann a British Zoologist. The main points of the cell theory are.

All living organisms are made up of the cells.

All cells arise from the pre-existing cell (Omnis cellula e cellula).

Virus does not follow the cell theory.

                                                      Detailed of Animal and Plant Cell

Types of cells:

There are primarily two types of cells, i.e.prokaryotic and eukaryotic cells.

                                                   Difference between the two cells

Chromosome:

chromosomes are the condensed form of the DNA. The cause of this condensation is special types of protein known as histones. When DNA is not condensed, it is called as chromatids. During cell division chromosomes show chromatids held together at a point called Centromere. End points of the chromosomes are known asTelomere. On the basis of position, centromere can be metacentric (present at the centre), sub metacentric (little away from the centre), acrocentric (situated close to the end), and telocentric (terminal centromere).

Types of Chromosomes:

Lampbrush Chromosomes: It was first discovered by the Balbiani , and it resemble the shape of the lamp brush.

Polytene Chromosomes: It was discovered by Balbiani  in salivary gland of  Chionomus larvae.

Genes:

Chromosomes also contains various genes. Gene acts as a unit  of inheritance in living organisms. It controls the transfer of genetic information from one generation to the next generation.