Lecture Notes: Types of Cells and their Functions

Basic Characteristics of All Cells

• Smallest living units in organisms
• Common features:
  • Cell Membrane: Separates inside of the cell from environment
  • Cytoplasm: Jelly-like fluid
  • DNA: Genetic material

Categories of Cells

Eukaryotic Cells

• Have organelles, including a nucleus
• Found in advanced, complex organisms (plants and animals)

Prokaryotic Cells

• No nucleus or membrane-enclosed organelles
• Genetic material not contained in a nucleus
• Always unicellular organisms (e.g., bacteria)

Organelles and Their Functions

Nucleus

• Control Center: Contains DNA
• DNA:
  • Determines cell's functions
  • Exists as chromatin when spread out
  • Condenses into chromosomes during cell division
• Nucleolus: Produces ribosomes

Ribosomes

• Synthesize proteins
• Located in cytoplasm or attached to endoplasmic reticulum (ER)

Endoplasmic Reticulum (ER)

• Rough ER: Has ribosomes attached
• Smooth ER: No ribosomes attached
• Transports materials like proteins

Golgi Apparatus

• Receives and customizes proteins from ER
• Modifies proteins by folding or adding other materials (lipids, carbohydrates)

Vacuoles

• Sac-like structures for storage
• Central vacuole in plant cells stores water

Lysosomes

• "Garbage collectors" of cells
• Break down damaged or worn out cell parts with enzymes

Mitochondria

• "Powerhouse" of the cell
• Produce ATP for energy via cellular respiration
• Found in both plant and animal cells

Cytoskeleton

• Maintains cell shape with microfilaments and microtubules

Chloroplasts (Plant Cells)

• Site of photosynthesis
• Contain green pigment chlorophyll

Cell Wall (Plant Cells)

• Provides shape, support, and protection
• Not found in animal cells

Unique Cell Structures

Cilia

• Found in respiratory tract cells
• Hair-like projections that trap inhaled particles

Flagella

• Found in some bacteria and human sperm cells
• Tail-like structure that aids in movement

Summary

• Eukaryotic cells have a nucleus and membrane-enclosed organelles
• Prokaryotic cells are unicellular without a nucleus
• All cells have a cell membrane, cytoplasm, and genetic material
• Plant cells have chloroplasts, but both plant and animal cells contain mitochondria