The nucleus was discovered in 1831 by Robert Brown. It is the largest organelle in eukaryotic cells, typically measuring 11-22 micrometers in diameter. The nucleus contains the cell's chromosomes, which are composed of DNA and protein. DNA contains the genetic information needed to build and organize cells.

2. In 1831 Robert Brown discovered the nucleus in the cell.
It is the largest organelle present in the eukaryotic cells.
In mammalian cells , the size of the nucleus typically varies
from 11 to 22 µm in diameter.
It is visible under a light microscope. It is acidic in nature. Any
basic stain can be used to see the nucleus.
It is surrounded by the double layered nuclear membrane with
pores to allow substances to enter and leave.
It is the controlling and co-coordinating centre of all the
activities of the cell.

3. Chromosomes are made up of nucleic acid and protein
, which is called nucleoprotein. There are 46 chromosomes in
each cell of the human body.
Nucleus contains chromosomes that are composed of DNA
(Deoxyribonucleic acid) molecules.DNA molecules contain the
information necessary for constructing and organizing cells.
In a cell which is not dividing, DNA is present as part of
chromatin material . Chromatin material is visible as
entangled mass of thread like structures. Whenever the cell
is about to divide, the chromatin material gets organized into
rod shaped chromosomes.
Functional segments of DNA are called genes. Genes contain
information for inheritance of features from parents to next
generation.

4. Prokaryotic cell Eukaryotic cell
Size generally small(1-10 microns) Size generally large(5-100microns)
Nuclear material not surrounded by Nuclear material surrounded by a
a nuclear membrane nuclear membrane
Chromosome single More than one chromosome
Nucleolus absent Nucleolus present
Membrane bound cell organelles Membrane bound cell organelles
absent present
Cell division by fission or budding Cell division by mitosis or meiosis
Example- Bacteria Example- Plants

5. Answer the following questions-
1.Nucleus is ______ in nature
2.In which year was cell discovered?
3.Fullform of DNA is ____________________
4. Chromosomes are made up of nucleic acid
And _______
5.Nucleolus is absent in___________ cell
Robert Brown
Chromosomes
protein
DNA