Cell Biology Study Notes

Cell Biology Study Notes

• Cell Theory

  • All living organisms are composed of cells.
  • The cell is the basic unit of life.
  • All cells arise from pre-existing cells.

• Types of Cells

  • Prokaryotic Cells
    • Lack a true nucleus and membrane-bound organelles.
    • Examples: Bacteria and Archaea.
  • Eukaryotic Cells
    • Have a true nucleus and membrane-bound organelles.
    • Examples: Plant cells, animal cells, fungi, and protists.

• Cell Structure

  • Plasma Membrane
    • Semi-permeable membrane that surrounds the cell.
    • Functions in transport, communication, and protection.
  • Nucleus
    • Contains genetic material (DNA).
    • Controls cell activities and gene expression.
  • Cytoplasm
    • Jelly-like substance where organelles are suspended.
    • Site of metabolic reactions.
  • Organelles
    • Mitochondria: Powerhouse of the cell, site of ATP production.
    • Ribosomes: Site of protein synthesis.
    • Endoplasmic Reticulum (ER):
      • Rough ER: Studded with ribosomes, synthesizes proteins.
      • Smooth ER: Synthesizes lipids and detoxifies.
    • Golgi Apparatus: Modifies, sorts, and packages proteins and lipids.
    • Lysosomes: Contain digestive enzymes for waste breakdown.
    • Chloroplasts: Site of photosynthesis in plant cells.
    • Vacuoles: Storage of materials; larger in plant cells.

• Cell Division

  • Mitosis: Process of cell division resulting in two identical daughter cells.
  • Meiosis: Special type of cell division that produces gametes (sperm and eggs) with half the chromosome number.

• Cell Communication

  • Cells communicate through chemical signals (hormones, neurotransmitters).
  • Signaling pathways involve receptors and second messengers.

• Cell Metabolism

  • Catabolism: Breakdown of molecules to release energy.
  • Anabolism: Synthesis of complex molecules from simpler ones, requiring energy.

• Cell Cycle

  • Phases: G1 (growth), S (DNA synthesis), G2 (preparation for mitosis), M (mitosis).
  • Regulation by cyclins and cyclin-dependent kinases (CDKs).

• Stem Cells

  • Undifferentiated cells with the potential to develop into various cell types.
  • Types: Embryonic stem cells and adult stem cells.

• Cellular Transport

  • Passive Transport: Movement of substances across the membrane without energy (e.g., diffusion, osmosis).
  • Active Transport: Movement against the concentration gradient, requiring energy (e.g., sodium-potassium pump).

These notes encapsulate fundamental aspects of cell biology, allowing for quick reference and review of key concepts.

Cell Theory and Cell Types

• All living organisms are comprised of cells, establishing the foundation of cell theory.
• The cell is recognized as the fundamental unit of life, essential for all biological functions.
• Cells originate from existing cells through processes of division.

Prokaryotic and Eukaryotic Cells

• Prokaryotic cells lack a true nucleus and membrane-bound organelles; examples include bacteria and archaea.
• Eukaryotic cells contain a true nucleus and membrane-bound organelles; examples include plant, animal, fungal, and protist cells.

Key Cellular Structures

• The plasma membrane is semi-permeable, facilitating transport, communication, and protection for the cell.
• The nucleus houses genetic material (DNA) and governs cell activities and gene expression.
• Cytoplasm is a jelly-like matrix where organelles reside, serving as the site for metabolic reactions.

Organelles and Their Functions

• Mitochondria: Known as the powerhouse of the cell, responsible for ATP production.
• Ribosomes: Essential for protein synthesis, either free-floating or attached to the rough endoplasmic reticulum.
• Endoplasmic Reticulum (ER):
  • Rough ER synthesizes proteins due to ribosome presence.
  • Smooth ER synthesizes lipids and detoxifies harmful substances.
• Golgi Apparatus: Modifies, sorts, and packages proteins and lipids for transport or secretion.
• Lysosomes: Contain digestive enzymes to break down cellular waste and debris.
• Chloroplasts: Organelles involved in photosynthesis, found in plant cells.
• Vacuoles: Storage organelles; notably larger in plant cells, holding various substances like nutrients and waste.

Cell Division Processes

• Mitosis results in two genetically identical daughter cells, crucial for growth and repair.
• Meiosis is a specialized division that produces gametes (sperm and eggs) with half the chromosome count.

Cell Communication Mechanisms

• Cells utilize chemical signals (hormones and neurotransmitters) to communicate.
• Signaling pathways include receptors and second messengers to relay messages and elicit responses.

Metabolic Processes

• Catabolism refers to the breakdown of molecules, providing energy for cellular activities.
• Anabolism involves the synthesis of complex molecules from simpler ones, requiring energy input.

Cell Cycle Phases

• The cell cycle comprises phases: G1 (growth), S (DNA synthesis), G2 (prep for mitosis), and M (mitosis).
• Regulation is driven by cyclins and cyclin-dependent kinases (CDKs) which ensure orderly progression through the cycle.

Stem Cells Characteristics

• Stem cells are undifferentiated, possessing the potential to develop into various cell types based on signals in their environment.
• Two main types: embryonic stem cells (which can become any cell type) and adult stem cells (more limited in potential).

Transportation Mechanisms

• Passive transport enables movement across the membrane without energy expenditure, includes processes like diffusion and osmosis.
• Active transport moves substances against their concentration gradient, requiring energy, exemplified by the sodium-potassium pump.