Powerpoint on Cells

6. Cell is the basic unit of life. All the life activities occur in
cells. The study of cells is called cell biology.
Discovery of cells
Cells were discovered by Robert Hooke in 1665.He observed
thin slices of cork through the microscope and said that, it
looked like honey comb like structures. These structures were
called small chambers which means cell.

7. Eukaryotic Cells
They have a definite nucleus, cell organelles which are
covered by a membrane. Large in size.
Prokaryotic Cells
These have no nucleus, no cell organelles and the nuclear
membrane is absent. Small in size.

10. Cell organelles are specific part for carrying out various
functions. Both prokaryotic and eukaryotic cells contain cell
organelles.
Nucleus : The information centre of the cell. Plays a major
role in regulating various activities of the cell like, synthesis
of protein.
Mitochondria : Is known as the powerhouse of the cell. Seen
abundantly in the liver, brain and muscle cells.
Endoplasmic Reticulum : Is the transport network for
molecules. Are of two types i.e. the rough ER and the smooth
ER.

11. • The rough ER has ribosomes on its surface.
• The smooth ER lacks ribosomes.
Ribosome : Is a complex of RNA and protein molecules.
Protein synthesis in the cell.
Golgi Complex : Processing and package of macromolecules
like proteins and lipids. Collects cell secretions.
Vacuoles : It is present only in plant cells. These vacuoles
they store water and separate excretory materials.
Centrosome : Is found only in animal cells. It plays a major
role in cell division.
Lysosomes : They contain digestive enzymes so, they digest
the worn out food particles and virus or bacteria.
Chloroplast : Is found in plants and algae. Produces
carbohydrates through photosynthesis.

12. Eukaryotic cells undergo two types of cell division namely
mitotic and meiotic cell division.
• Mitosis – Is the cell division where a mother cell divides
into two daughter cells.
STAGES IN MITOSIS

13. • Meiosis – The parent cells recombine to form a zygote.It
occurs only in sex cells. Cells divide twice to form four
daughter cells.
STAGES IN MEIOSIS

14. A Textbook of class IX by SCERT,Kerala (page no:60- 61)
A Textbook of class VIII BY SCERT,kerala (page no: 12-15)
Teacher’s handbook of class VIII