Cell Biology Basics

Cell Organelles

• Plasma Membrane:
  • Also known as the cell membrane or cytoplasmic membrane
  • Semi-permeable membrane that separates the cell from its environment
  • Regulates the movement of substances in and out of the cell
  • Composed of a phospholipid bilayer with embedded proteins
• Nucleus:
  • Control center of the cell where DNA is stored
  • Surrounded by a double membrane called the nuclear envelope
  • Contains nucleolus, where ribosome synthesis occurs
• Other Organelles:
  • Mitochondria: generates energy for the cell through cellular respiration
  • Endoplasmic Reticulum (ER): involved in protein synthesis, transport, and storage
  • Ribosomes: site of protein synthesis
  • Lysosomes: contains digestive enzymes for breaking down and recycling cellular waste
  • Golgi Apparatus: involved in protein modification, sorting, and secretion

Structures of Microscope

• Light Microscope:
  • Uses visible light to produce an image
  • Limited resolution (0.2-0.3 μm)
• Electron Microscope:
  • Uses a beam of electrons to produce an image
  • Higher resolution (1-10 nm) than light microscope
• Scanning Electron Microscope:
  • Produces a three-dimensional image of the cell surface
  • Higher resolution than light microscope

Discoveries about Cells

• Antonie van Leeuwenhoek (1676): first observed microorganisms using a microscope
• Matthias Jakob Schleiden and Theodor Schwann (1839): formulated the cell theory, which states that:
  1. All living organisms are composed of cells
  2. Cells are the basic units of life
  3. All cells arise from pre-existing cells

Basic Functions of Cells

• Metabolism: cells carry out chemical reactions to maintain homeostasis and energy production
• Growth and Development: cells divide, grow, and differentiate to form tissues and organs
• Response to Stimuli: cells respond to changes in their environment through signal transduction pathways
• Reproduction: cells divide to produce new cells, ensuring the continuation of life