Cell Structure and Organization

1.1 Structure of Living Organisms

• Cells: Basic unit of life.
• Two types of cells:
  • Animal Cells
  • Plant Cells

Cell Structure	Function	Found in
Cell Membrane	Controls movement of substances	Plant and Animal
Cytoplasm	Site of chemical reactions	Plant and Animal
Nucleus	Controls cell activities, contains DNA	Plant and Animal
Mitochondria	Site of aerobic respiration	Plant and Animal
Ribosomes	Synthesize proteins	Plant and Animal
Cell Wall	Provides structure (cellulose)	Plant
Chloroplasts	Site of photosynthesis (contains chlorophyll)	Plant
Vacuole	Stores water, nutrients, and waste	Plant

1.2 Cell Specialization

• Specialized Cells: Adapted for specific functions.
• Examples:
  • Red Blood Cell: No nucleus, biconcave shape, carries oxygen.
  • Root Hair Cell: Large surface area, absorbs water and minerals.
  • Nerve Cell: Long with branches, transmits electrical signals.
  • Ciliated Cell: Has cilia, sweeps mucus in airways.

1.3 Levels of Organization

• Cells → Tissues → Organs → Organ Systems → Organism.

1.4 Differences Between Plant and Animal Cells

Feature	Plant Cell	Animal Cell
Cell Wall	Present	Absent
Chloroplasts	Present	Absent
Vacuole	Large and central	Small or absent
Shape	Fixed, rectangular	Irregular

1.5 Magnification

• Formula: $\text{Magnification}=\frac{\text{Image size}}{\text{Actual size}}$