Cell Biology Lecture Notes

Overview of Cells

• Cell Basics: Smallest living units of an organism.
• Common Features of All Cells:
  • Cell membrane: Separates inside cell from environment.
  • Cytoplasm: Jelly-like fluid inside cell.
  • DNA: Genetic material of the cell.

Categories of Cells

• Eukaryotic Cells

  • Contain organelles (including nucleus).
  • Example organisms: Plants, animals.
  • More advanced and complex.

• Prokaryotic Cells

  • Lack a nucleus and membrane-enclosed organelles.
  • Genetic material not in nucleus.
  • Always unicellular (e.g., bacteria).

Organelles and Their Functions

• Definition: Specialized parts of a cell (means "little organ").
• Nucleus: Control center containing DNA.
  • DNA dictates cellular function.
  • Chromatin: Spread out form of DNA.
  • Chromosomes: Condensed DNA structures for cell division.
  • Nucleolus: Makes ribosomes.
• Ribosomes
  • Synthesize proteins.
  • Can be free-floating or attached to ER.
• Endoplasmic Reticulum (ER)
  • Rough ER: Has ribosomes attached.
  • Smooth ER: No ribosomes.
  • Transports synthesized proteins.
• Golgi Apparatus (Golgi Body)
  • Customizes proteins into usable shapes/forms.
  • Adds materials like lipids or carbohydrates to proteins.
• Vacuoles
  • Store various materials.
  • Central vacuole in plant cells stores water.
• Lysosomes
  • Garbage collectors of the cell.
  • Break down cellular debris with enzymes.
• Mitochondria
  • Powerhouse of the cell.
  • Produce ATP energy molecules via cellular respiration.
  • More mitochondria in cells requiring more energy.
• Cytoskeleton
  • Maintains cell shape.
  • Composed of microfilaments (proteins) and microtubules (hollow tubes).
• Chloroplasts (in photoautotrophic organisms)
  • Site of photosynthesis.
  • Contain chlorophyll (green pigment).
• Cell Wall (in plant cells)
  • Surrounds cell membrane.
  • Provides shape, support, and protection.

Unique Cell Structures

• Cilia (in respiratory tract cells)
  • Hair-like projections.
  • Move in waves to trap and expel particles.
• Flagella
  • Tail-like structures for movement/propulsion.
  • Found in bacteria and sperm cells.

Key Takeaways

• Eukaryotic cells: Nucleus and organelles; found in plants and animals.
• Prokaryotic cells: No nucleus; always unicellular.
• All cells: Have a cell membrane, cytoplasm, and genetic material.
• Plant cells: Have chloroplasts (for photosynthesis) and mitochondria.
• Animal cells: Do not have chloroplasts but have mitochondria.