Cell Biology Lecture Notes

Overview

• Cells are the smallest living units of an organism.
• All cells share three components:
  • Cell membrane: Separates the inside of the cell from its environment.
  • Cytoplasm: Jelly-like fluid inside the cell.
  • DNA: The cell's genetic material.

Types of Cells

• Eukaryotic Cells:

  • Contain organelles, including a nucleus.
  • More advanced and complex.
  • Found in plants and animals.

• Prokaryotic Cells:

  • Do not have a nucleus or membrane-enclosed organelles.
  • Contain genetic material not within a nucleus.
  • Unicellular organisms, such as bacteria.

Organelles

• Organelles: "Little organs" with specialized functions.

Nucleus

• Control Center
  • Contains DNA, dictating cell function and operation.
  • Chromatin: Tangled, spread-out form of DNA.
  • Chromosomes: Condensed DNA structures for cell division.
  • Nucleolus: Site of ribosome production.

Ribosomes

• Synthesize proteins.
• Located in cytoplasm or attached to the Endoplasmic Reticulum (ER).

Endoplasmic Reticulum (ER)

• Rough ER: Ribosomes attached.
• Smooth ER: No ribosomes attached.
• Transports materials such as proteins.

Golgi Apparatus

• Customizes proteins into usable forms.
• Adds lipids or carbohydrates to proteins.

Vacuoles

• Sac-like structures for storage, e.g., central vacuole in plants stores water.

Lysosomes

• Act as garbage collectors for worn-out cell parts.
• Contain enzymes for breakdown of debris.

Mitochondria

• "Powerhouse" of the cell.
• Produces ATP through cellular respiration.

Cytoskeleton

• Maintains cell shape.
• Includes microfilaments and microtubules.

Chloroplasts (in Plant Cells)

• Site of photosynthesis.
• Contains green pigment chlorophyll.

Cell Wall (in Plant Cells)

• Provides shape, support, and protection.
• Absent in animal cells.

Special Structures in Some Cells

• Cilia: Microscopic hair-like projections in respiratory tract cells.

  • Help trap and expel inhaled particles.

• Flagella: Tail-like structures aiding in movement.

  • Present in some bacteria and human sperm cells.

Summary

• Eukaryotic cells: Plant and animal cells with nucleus and organelles.
• Prokaryotic cells: Unicellular, lack nucleus and organelles.
• Common features: Cell membrane, cytoplasm, genetic material.
• Plant cells have chloroplasts; both plant and animal cells have mitochondria.