Cell Biology Study Notes

Cell Biology Study Notes

1. Cell Theory

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

2. Types of Cells

• Prokaryotic Cells:
  • Lack a nucleus and membrane-bound organelles.
  • Examples: Bacteria and Archaea.
• Eukaryotic Cells:
  • Contain a nucleus and membrane-bound organelles.
  • Examples: Animal cells, plant cells, fungi, and protists.

3. Cell Structure

• Cell Membrane:

  • Semi-permeable barrier that regulates movement in and out of the cell.
  • Composed of a phospholipid bilayer with embedded proteins.

• Nucleus:

  • Contains genetic material (DNA).
  • Surrounded by a nuclear envelope with pores for substance exchange.

• Organelles:

  • Mitochondria: Energy production through cellular respiration.
  • Ribosomes: Protein synthesis; can be free in cytoplasm or attached to the endoplasmic reticulum.
  • Endoplasmic Reticulum (ER):
    • Rough ER: Studded with ribosomes; synthesizes proteins.
    • Smooth ER: Synthesizes lipids and detoxifies drugs.
  • Golgi Apparatus: Modifies, sorts, and packages proteins and lipids for secretion or delivery.
  • Lysosomes: Contain enzymes for digestion of cellular waste and macromolecules.
  • Chloroplasts (in plant cells): Site of photosynthesis.

4. Cell Membrane Dynamics

• Fluid Mosaic Model: Describes the cell membrane as a mosaic of diverse protein molecules floating in or on the fluid lipid bilayer.
• Transport Mechanisms:
  • Passive Transport: Movement of molecules without energy input (e.g., diffusion, osmosis).
  • Active Transport: Movement of molecules against the concentration gradient using energy (e.g., sodium-potassium pump).

5. Cell Division

• Mitosis: Process of cell division resulting in two identical daughter cells; essential for growth and repair.

  • Phases: Prophase, Metaphase, Anaphase, Telophase.

• Meiosis: Specialized cell division producing gametes (sperm and eggs) with half the chromosome number; essential for sexual reproduction.

  • Involves two rounds of division: Meiosis I and Meiosis II.

6. Cell Communication

• Signal Transduction: Process by which a cell responds to external signals through receptors and intracellular pathways.
• Types of Signaling:
  • Autocrine: Cell signals itself.
  • Paracrine: Signals to nearby cells.
  • Endocrine: Hormones released into the bloodstream affecting distant cells.

7. Cellular Metabolism

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

8. Specialization and Differentiation

• Cells can differentiate into specialized types to perform specific functions; influenced by genetic and environmental factors.

9. Stem Cells

• Types:
  • Embryonic Stem Cells: Pluripotent, can differentiate into any cell type.
  • Adult Stem Cells: Multipotent, limited to specific cell types.
• Potential applications in regenerative medicine and research.

10. Cellular Adaptations

• Cells can adapt to changes in their environment through various mechanisms, including hypertrophy (increase in size), hyperplasia (increase in number), and atrophy (decrease in size).

These notes provide a concise overview of key concepts in cell biology, serving as a quick reference for study and review.

Cell Biology Study Notes

Cell Theory

• Composed of cells, the fundamental building blocks of life.
• Establishes that cells are the basic unit of life.
• States that all cells originate from pre-existing cells.

Types of Cells

• Prokaryotic Cells:
  • No nucleus or membrane-bound organelles.
  • Examples include Bacteria and Archaea.
• Eukaryotic Cells:
  • Contain a nucleus and defined organelles.
  • Include animal cells, plant cells, fungi, and protists.

Cell Structure

• Cell Membrane:
  • Acts as a semi-permeable barrier, controlling entry and exit of substances.
  • Composed of a phospholipid bilayer with integrated proteins.
• Nucleus:
  • Houses genetic information (DNA).
  • Encased by a nuclear envelope with pores facilitating material exchange.
• Organelles:
  • Mitochondria: Generate energy via cellular respiration.
  • Ribosomes: Responsible for protein synthesis; found free or on the endoplasmic reticulum (ER).
  • Endoplasmic Reticulum (ER):
    • Rough ER: Ribosome-studded, involved in protein synthesis.
    • Smooth ER: Functions in lipid synthesis and drug detoxification.
  • Golgi Apparatus: Modifies, sorts, and packages proteins and lipids for transport.
  • Lysosomes: Digest cellular waste and macromolecules through enzymatic action.
  • Chloroplasts: Present in plant cells, serve as the site for photosynthesis.

Cell Membrane Dynamics

• Fluid Mosaic Model:
  • Describes the cell membrane as a dynamic structure with proteins dispersed in a fluid lipid layer.
• Transport Mechanisms:
  • Passive Transport: Movement of molecules without energy (e.g., diffusion and osmosis).
  • Active Transport: Requires energy to move molecules against their concentration gradient (e.g., sodium-potassium pump).

Cell Division

• Mitosis:
  • Results in two identical daughter cells; crucial for organism growth and tissue repair.
  • Involves phases: Prophase, Metaphase, Anaphase, Telophase.
• Meiosis:
  • Produces gametes (sperm and eggs) with half the chromosome count; critical for sexual reproduction.
  • Comprises two halves of division: Meiosis I and Meiosis II.

Cell Communication

• Signal Transduction:
  • Mechanism for cellular response to external signals via receptors and signaling pathways.
• Types of Signaling:
  • Autocrine: Cell signals itself, regulating its own functions.
  • Paracrine: Cell signals nearby cells, facilitating local communication.
  • Endocrine: Hormonal signals released into the bloodstream, affecting distant target cells.

Cellular Metabolism

• Catabolism:
  • Involves the breakdown of complex molecules to release energy.
• Anabolism:
  • Encompasses the synthesis of complex molecules from simpler ones, requiring energy input.

Specialization and Differentiation

• Cells can specialize into distinct types to carry out specific roles, influenced by genetics and environmental factors.

Stem Cells

• Types:
  • Embryonic Stem Cells: Pluripotent, capable of differentiating into any cell type.
  • Adult Stem Cells: Multipotent, restricted to specific cell types.
• Possess potential for applications in regenerative medicine and scientific research.

Cellular Adaptations

• Cells adapt to environmental changes through mechanisms such as:
  • Hypertrophy: Increase in cell size.
  • Hyperplasia: Increase in cell number.
  • Atrophy: Decrease in cell size.