Cell Biology: Metabolism and Division

Cell Biology Study Notes

Cell Metabolism

• Definition: The sum of all chemical reactions within a cell to maintain life.
• Types:
  • Catabolism: Breakdown of molecules to obtain energy (e.g., glycolysis, Krebs cycle).
  • Anabolism: Synthesis of complex molecules from simpler ones (e.g., protein synthesis).
• ATP: Primary energy currency of the cell, produced mainly in mitochondria.
• Enzymes: Biological catalysts that speed up metabolic reactions by lowering activation energy.

Cell Division

• Types:
  • Mitosis: Cellular division resulting in two identical daughter cells; essential for growth and repair.
    • Phases: Prophase, Metaphase, Anaphase, Telophase, Cytokinesis.
  • Meiosis: Division that reduces chromosome number by half, producing gametes for sexual reproduction.
    • Involves two rounds of division: Meiosis I and Meiosis II.
• Regulation: Controlled by cell cycle checkpoints (G1, S, G2, M phases) to ensure proper division.

Cell Communication

• Purpose: Allows cells to send and receive signals, facilitating coordination and response to the environment.
• Types of Signaling:
  • Autocrine: Signals affect the same cell that produces them.
  • Paracrine: Signals affect nearby cells.
  • Endocrine: Hormones are released into the bloodstream to affect distant cells.
  • Juxtacrine: Direct signaling between adjacent cells through cell-to-cell contact.
• Receptors: Proteins on cell surfaces or within cells that bind to signaling molecules, initiating a response.

Cell Function

• Homeostasis: Maintenance of stable internal conditions (pH, temperature, concentration of ions).
• Specialization: Different types of cells (e.g., neurons, muscle cells, epithelial cells) performing distinct functions.
• Transport Mechanisms:
  • Passive Transport: Movement of substances across cell membranes without energy (e.g., diffusion, osmosis).
  • Active Transport: Requires energy to move substances against their concentration gradient (e.g., sodium-potassium pump).

Cell Structure

• Key Components:
  • Cell Membrane: Phospholipid bilayer that encapsulates the cell, controlling movement in and out.
  • Nucleus: Contains genetic material (DNA); regulates cell activity and gene expression.
  • Cytoplasm: Jelly-like substance where cellular components are suspended; site for metabolic processes.
  • Organelles:
    • Mitochondria: Powerhouse of the cell; site of ATP production.
    • Ribosomes: Sites of protein synthesis.
    • Endoplasmic Reticulum (ER):
      • Rough ER: Studded with ribosomes; involved in protein synthesis.
      • Smooth ER: Involved in lipid synthesis and detoxification.
    • Golgi Apparatus: Modifies, sorts, and packages proteins and lipids for secretion or delivery.
    • Lysosomes: Contain digestive enzymes; break down waste materials.
    • Cell Wall: Found in plant cells; provides structure and protection (not in animal cells).

Cell Metabolism

• The sum of all chemical reactions happening within a cell to sustain life
• Catabolism breaks down molecules to release energy while anabolism builds complex molecules.
• ATP is the cell's main energy source, primarily produced within the mitochondria.
• Enzymes act as biological catalysts accelerating metabolic reactions.

Cell Division

• Mitosis produces two identical daughter cells. Crucial for growth and repairing damaged tissues.
• Meiosis, on the other hand, halves the chromosome number, resulting in gametes, the reproductive cells.
• Meiosis involves two rounds of division called Meiosis I and Meiosis II
• Cell cycle checkpoints (G1, S, G2, M) ensure proper division.

Cell Communication

• Cell communication allows cells to coordinate activities by sending and receiving signals.
• Autocrine signals act on the same cell producing them.
• Paracrine signals affect nearby cells.
• Endocrine signals (hormones) circulate through the bloodstream to reach distant cells.
• Juxtacrine signals involve direct contact between neighboring cells.
• Receptors, proteins on the cell surface or inside the cell bind to signaling molecules to trigger responses.

Cell Function

• Homeostasis maintains stable internal conditions such as pH, temperature, and ion concentration.
• Specialization allows different cell types (like neurons, muscle cells, epithelial cells) to carry out specific tasks.
• Passive transport moves substances across the cell membrane without energy, for example, diffusion and osmosis.
• Active transport requires energy to move substances against their concentration gradient, for example, the sodium-potassium pump.

Cell Structure

• Cell membrane is a phospholipid bilayer that surrounds and controls what enters and exits the cell.
• Nucleus is the control center containing DNA, responsible for regulating cell activity and gene expression.
• Cytoplasm is a jelly-like substance containing cellular components, where metabolic processes take place.
• Organelles are specialized structures within the cell:
• Mitochondria are the powerhouses of the cell, where ATP is produced.
• Ribosomes are responsible for protein synthesis.
• Endoplasmic Reticulum (ER):
  • Rough ER is studded with ribosomes and involved in protein synthesis.
  • Smooth ER synthesizes lipids and detoxifies harmful substances.
• Golgi Apparatus modifies, sorts, and packages proteins and lipids for secretion or delivery within the cell.
• Lysosomes contain digestive enzymes breaking down waste materials.
• Cell wall is found in plant cells, providing structure and protection (not present in animal cells).

Explore the fundamentals of cell metabolism and division in this informative quiz. Delve into the processes of catabolism and anabolism, and learn about the phases of mitosis and meiosis. Test your knowledge on enzymes, ATP, and the regulation of the cell cycle.