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⬆️ TOP EDUCATION ⬆️
CLASS 9th SCIENCE
CH:5 THE FUNDAMENTAL UNIT OF LIFE
NOTES
1. Cell:
👉The cell is the basic structural and functional unit of all living organisms.
👉Cells vary in shape, size, and functions.
👉Cells can be classified into two types: prokaryotic cells and eukaryotic cells.
2. Prokaryotic Cells:
👉Prokaryotic cells are found in bacteria and blue-green algae.
👉They lack a well-defined nucleus and other membrane-bound organelles.
👉The genetic material in prokaryotic cells is present in the form of a single circular chromosome.
👉Examples: Bacteria like Escherichia coli (E. coli).
3. Eukaryotic Cells:
👉Eukaryotic cells are found in plants, animals, fungi, and protists.
👉They have a well-defined nucleus and other membrane-bound organelles.
👉The genetic material in eukaryotic cells is organized into linear chromosomes within the nucleus.
👉Examples: Plant cells, animal cells, fungal cells.
4. Cell Organelles:
👉Cell organelles are specialized structures within the cell that perform specific functions.
Some important organelles are:
a.Nucleus: It contains the genetic material and controls the cell's activities.
b. Cytoplasm: It is a jelly-like substance that fills the cell and contains organelles.
c.Cell Membrane: It forms the outer boundary of the cell and regulates the movement of substances in and out of the cell.
d. Mitochondria: They are the powerhouse of the cell and produce energy.
e. Endoplasmic Reticulum (ER): It is involved in the synthesis and transport of proteins.
f.Golgi Apparatus: It modifies, sorts, and packages proteins for transport.
g. Ribosomes: They are involved in protein synthesis.
h. Vacuoles: They store water, nutrients, and waste materials.
i.Lysosomes: They contain enzymes for intracellular digestion.
👉j. Chloroplasts (found in plant cells): They carry out photosynthesis.
5. Cell Theory:
The cell theory states that:
a. All living organisms are composed of cells.
b. The cell is the basic unit of life.
👉c. Cells arise from pre-existing cells.
6. Cell Division:
👉Cell division is the process by which cells reproduce.
👉It is of two types: mitosis and meiosis.
👉Mitosis is involved in growth, repair, and asexual reproduction.
👉Meiosis is involved in the formation of gametes (sex cells) for sexual reproduction.
☆Remember to refer to your textbook and class notes for more comprehensive information on
the topic. These notes serve as a brief overview.
