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CBSE 9th Class Science- The Fundamental Unit of Life – Nucleus

CBSE 9th Class Science The Fundamental Unit of Life - Nucleus

CBSE 9th Class Science- The Fundamental Unit of Life – Nucleus

In this article, we will discuss the topic  ‘Nucleus’ from the chapter ‘The Fundamental Unit of Life’ out for 9th Class Science.

  • The cell is the basic structure of life, as the smallest unit of life capable of replicating independently and it has been called the “building blocks of life”.


  • The nucleus is a membrane-bound structure that contains the cell’s hereditary information and controls the cell’s growth and reproduction.


  • It is generally the most prominent organelle in the cell. It is surrounded by a structure called the nuclear envelope.


  • This membrane separates the contents of the nucleus from the cytoplasm. The cell’s chromosomes are also enclosed within it.


  • Chromosomes have DNA that administers the genetic information necessary for the production of other cell components and for reproduction of life.

CBSE 9th Class Science The Fundamental Unit of Life - Nucleus

  • The nucleus is a membrane-bound structure that composes the genetic material of a cell.


  • It is not just a storage compartment for DNA but also happens to be the home of some necessary cellular processes.


  • The duplication of DNA in the nucleus. This process has been named replication and creates an identical copy of the DNA. Creating two identical copies of the host or body is the first step in cell division, where each new cell will get its own set of instructions.


  • Transcription is the process of creating different types of RNA from DNA, takes place in the nucleus of a cell.
  • The nucleus is small, round and membrane-bound structure found in the cell.
  • The fluid inside the nucleus surrounded by the nuclear membrane is called nucleoplasm.
  • It controls the cell’s growth and reproduction because it contains cell’s hereditary information.
  • It is covered by a dual layer called nuclear membrane.
  • The nuclear membrane contains pores due to which materials can travel both inside the nucleus from its outer surrounding i.e. cytoplasm.

CBSE 9th Class Science The Fundamental Unit of Life - Nucleus

Fig. The nucleus of a Cell



Watch and understand the concept of the nucleus and its structure with interactive animated video, click CBSE 9th Class Science for demos.

CBSE 9th Class Science The Fundamental Unit of Life - Nucleus

Anatomy of Nucleus

  • The nucleus contains some thread like structures called chromatin. It exists during the resting stage of the cell.
  • The chromatin contains DNA (Deoxyribonucleic acid), RNA (Ribo-Nucleic acid) and proteins.
  • The nucleus contains some rod-shaped structures in a cell that contains the hereditary information. They are called chromosome.
  • They are formed when the chromatin condenses together when the cell is about to divide.
  • Chromosomes contain DNA and nuclear proteins.
  • They contain the hereditary information for the inheritance of features from the parents to the offspring as DNA.
  • The DNA molecules contain the information for construction and organization of cells. Genes are the functional segments of DNA.
  • The human body has 23 pairs of sex chromosomes. A boy has one X chromosome and one Y chromosome whereas a girl has two X chromosomes.
  • The nucleus of a cell divides itself to give rise to new offspring.
  • Genes present in the chromosomes decide the hereditary characters.

CBSE 9th Class Science The Fundamental Unit of Life - Nucleus


For live tuitions and animated videos to understand the concepts click Class 9th Science.

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