What Is A Cell Made Up Of? What Is The Structural Organisation Of A Cell?

Key Notes:

Definition of a Cell

• A cell is the basic structural, functional, and biological unit of all living organisms.
• It is often called the “building block of life.”

Components of a Cell

• Cell Membrane (Plasma Membrane):
  • A thin, flexible barrier that surrounds the cell.
  • Controls the entry and exit of substances.
  • Made up of a lipid bilayer with embedded proteins.
• Cytoplasm:
  • The jelly-like substance between the cell membrane and the nucleus.
  • Contains cell organelles and is the site for many biochemical activities.
• Nucleus:
  • The control center of the cell containing genetic material (DNA).
  • Enclosed by the nuclear membrane and contains nucleoplasm, nucleolus, and chromatin.

Cell Organelles and Their Functions

• Mitochondria:
  • Known as the “powerhouse of the cell.”
  • Produces energy in the form of ATP through cellular respiration.
• Endoplasmic Reticulum (ER):
  • Rough ER has ribosomes and helps in protein synthesis.
  • Smooth ER is involved in lipid synthesis and detoxification.
• Golgi Apparatus:
  • Modifies, sorts, and packages proteins and lipids for secretion or use within the cell.
• Lysosomes:
  • Contain digestive enzymes to break down waste and cellular debris.
• Ribosomes:
  • Sites of protein synthesis, found free-floating in the cytoplasm or attached to the ER.
• Chloroplasts (in plant cells):
  • Contain chlorophyll for photosynthesis.
• Vacuoles:
  • Storage sacs for water, nutrients, and waste.
  • Larger in plant cells for maintaining turgidity.
• Cytoskeleton:
  • Provides structural support and shape to the cell.

Structural Organization of Cells

• Prokaryotic Cells:
  • Lack a well-defined nucleus; genetic material is free-floating in the cytoplasm.
  • Examples: Bacteria and Archaea.
• Eukaryotic Cells:
  • Have a well-defined nucleus and membrane-bound organelles.
  • Examples: Plant and animal cells.

Differences Between Plant and Animal Cells

• Plant Cells:
  • Have a cell wall, chloroplasts, and a large central vacuole.
• Animal Cells:
  • Lack a cell wall and chloroplasts but have small vacuoles and centrioles.

Significance of Cellular Organization

• The structural organization ensures proper functioning and specialization of cells.
• Multi-cellular organisms exhibit division of labor, with different cells performing specific roles.

Microscopic Observation

• Cells can be observed using a microscope.
• Stains like methylene blue and iodine help in highlighting cell components.