Question

What is nucleus . Define nucleus

Answer 1

Answer:

nucleus is a cell organelle which carries the information for function of the cell. it is the major site where genetic material is located.

Explanation:

• Nucleus as a cell organelle was first described by Robert Brown as early as 1831.
• Later the material of the nucleus stained by the basic dyes was given the name chromatin by Flemming.
• The interphase nucleus (nucleus of a cell when it is not dividing) has highly extended and elaborate nucleoprotein fibres called chromatin, nuclear matrix and one or more spherical bodies called nucleoli (sing.: nucleolus)
• Normally, there is only one nucleus per cell, variations in the number of nuclei are also frequently observed.
• Some mature cells even lack nucleus, e.g., erythrocytes of many mammals and sieve tube cells of vascular plants.
• The nuclear matrix or the nucleoplasm contains nucleolus and chromatin.
• The nucleoli are spherical structures present in the nucleoplasm.
• The content of nucleolus is continuous with the rest of the nucleoplasm as it is not a membrane bound structure.
• It is a site for active ribosomal RNA synthesis.
• Larger and more numerous nucleoli are present in cells actively carrying out protein synthesis.
• Electron microscopy has revealed that the nuclear envelope, which consists of two parallel membranes with a space between (10 to 50 nm) called the perinuclear space, forms a barrier between the materials present inside the nucleus and that of the cytoplasm.
• The outer membrane usually remains continuous with the endoplasmic reticulum and also bears ribosomes on it.
• At a number of places the nuclear envelope is interrupted by minute pores, which are formed by the fusion of its two membranes.
• These nuclear pores are the passages through which movement of RNA and protein molecules takes place in both directions between the nucleus and the cytoplasm.

Answer 2

Answer:

Nucleus is a cell organelle.It is called as the King or Brain of the cell.

Explanation:

Nucleus is the king or brain of the cell because it controls and coordinates all functions of the cell.Nucleus is surrounded by a membrane called nuclear membrane.The nuclear membrane has pore on it to allow the transport of material.Nucleus has a round structure inside it called as nucleolus.Inside the nuclear membrane there is a chromatin network.The chromatin network organize into chromosomes while cell division.The chromosomes carry the genetic material called DNA.The functional segments of DNA are called as Genes.

Functions of Nucleus:

• Nucleus helps in Inheritance of character from parents to offspring.
• Nucleus controls and coordinates all function of the cell
• Nucleus plays a central role in reproduction in Unicellular organisms.

Discovery of Nucleus-

• Franz Baur first described about cell.
• Nuclear was first discovered and explained by Robert Brown in 1831.
• It is the first cell organelle to be discovered.

Hope my answer helped you!!!