Class 9 Science - Fundamental Unit of Life (Cell)

Introduction

• Prashant Bhaiya’s interesting style of teaching science
• One short video for every chapter of Class 9
• Will cover every line of NCERT
• Main goal: Make science fun

First Chapter: Fundamental Unit of Life

• Cell: Fundamental unit of life
• Living things are made up of cells
• Definition and importance of cells

Structure and Types of Cells

• Unicellular Organisms: Single-celled organisms (Protozoa, Bacteria)
• Multicellular Organisms: Multi-celled organisms (Humans, Plants)
• Size and Shape of Cells: Varied types

Cell Theory

• Robert Hooke: Discovery of dead cells
• Antony van Leeuwenhoek: Discovery of living cells
• Robert Brown: Discovery of the nucleus
• Three significant points of Cell Theory:
  1. All living organisms are made up of cells
  2. Cells can be one or more in number
  3. New cells arise from pre-existing cells

Various Parts of a Cell

• Plasma Membrane: Bodyguard, selectively permeable membrane
• Cell Wall: Only in plants, made of cellulose
• Nucleus: Brain of the cell, DNA and genetic information
• Cytoplasm: Jelly-like substance
• Cell Organelles: For various functions

Major Cell Organelles

1. Ribosomes: Protein factory
2. Endoplasmic Reticulum:
   • Rough (Ribosomes present): Protein synthesis
   • Smooth: Lipid synthesis and detoxification
3. Golgi Apparatus: Storage, modification, and packaging
4. Lysosomes: Suicide bags, digestive enzymes
5. Vacuoles: Storage sac, large in plants, small in animals
6. Mitochondria: Powerhouse, ATP production
7. Plastids (only in plants):
   • Chloroplast: Chlorophyll, photosynthesis
   • Chromoplast: Colored pigments
   • Leucoplast: Storage of starch, oil, proteins

Cell Division

• Mitosis: Two daughter cells, same number of chromosomes
• Meiosis: Four daughter cells, half the number of chromosomes
• Mitosis: Growth and repair
• Meiosis: Production of gametes

Other Important Points

• Plasma Membrane: Lipids and proteins
• Endocytosis and Exocytosis: Movement of material in and out of the cell
• Three scientists of Cell Theory: Schleiden, Schwann, Virchow
• Diffusion and Osmosis: High to low concentration, semi-permeable membrane
• Hypertonic and Hypotonic Solutions: Shrink and swell
• Prokaryotic and Eukaryotic Cells: Size, nucleus, organelles

Suggestions and Conclusion

• Download notes and copy them fairly
• Use stories to remember
• Be fearless, become the powerhouse of your own life

Thank You

• Request the next chapter in the comments
• Prashant Bhaiya is always here to help