Structure and Function of a Cell

Common Parts of a Cell

1. Cell Membrane

   • Selectively permeable membrane.
   • Functions:
     • Allows essential substances (e.g., water, oxygen) to enter the cell.
     • Removes toxic substances and waste products (e.g., carbon dioxide) out of the cell.

2. Cytoplasm

   • Thick, jelly-like structure providing shape to the cell.
   • Functions:
     • Site of cellular reactions (e.g., protein formation, respiration).
     • Contains important organelles (e.g., mitochondria, ribosomes, endoplasmic reticulum, Golgi bodies, lysosomes).

3. Nucleus

   • Contains DNA, the blueprint for cellular functions.
   • Control center of the cell.
   • Functions:
     • Controls cell development, survival, growth, and reproduction.
     • Contains nucleolus which forms ribosomal RNA and ribosomes.

Organelles and Their Functions

Ribosomes

• Floating organelles in the cytoplasm.
• Function: Protein synthesis for cell growth and repair.

Endoplasmic Reticulum (ER)

• Two types: Rough ER and Smooth ER.
  • Rough ER
    • Contains ribosomes.
    • Assists in protein production.
    • Encloses proteins in vesicles.
  • Smooth ER
    • Does not have ribosomes.
    • Produces lipids and performs detoxification.

Vesicles

• Trunks within the cell transporting substances.

Golgi Body (Golgi Apparatus)

• Port of the cell.
• Functions:
  • Receives proteins from Rough ER.
  • Modifies proteins by shaping and adding components like lipids or carbohydrates.
  • Packages proteins in vesicles for transport to their destination.

Mitochondria

• Power station of the cell.
• Functions:
  • Provides energy in the form of ATP through cellular respiration.
  • Contains its own DNA.

Lysosomes

• Digestive part of the cell.
• Function:
  • Breaks down food into simpler substances (e.g., carbohydrates to glucose, proteins to amino acids).

Vacuoles

• Storehouse of the cell.
• Function:
  • Stores water, food, minerals, nutrients, and waste products.
  • Varies in size between plant and animal cells.

Conclusion

• Further exploration of differences between animal and plant cells will be covered in the next lecture.