Cell Structure and Transport

Microscopes in Biology

• Types of Microscopes

  • Light Microscopes
    • Used in labs
    • Cheaper, see living cells
    • Lower resolution
  • Electron Microscopes
    • Higher resolution, see smaller details
    • Expensive, only see dead specimens

• Measurement Units

  • Nanometer (nm) = 10^-9 m
  • Micrometer (µm) = 10^-6 m
  • Millimeter (mm) = 10^-3 m

• Calculation Triangle for Microscopy

  • Real size = Size of image / Magnification
  • Magnification = Size of image / Real size
  • Size of image = Magnification x Real size

Types of Cells

Eukaryotic Cells

• Animal Cells

  • Organelles:
    • Nucleus: Holds DNA, "brain" of the cell
    • Cell Membrane: Controls entry and exit of substances
    • Mitochondria: Site of respiration, provides energy
    • Ribosomes: Site of protein synthesis
    • Cytoplasm: Site of chemical reactions

• Plant Cells

  • Shared Organelles: Nucleus, Mitochondria, Cell Membrane
  • Unique Organelles:
    • Cell Wall: Provides rigidity
    • Vacuole: Stores sugars, maintains cell structure
    • Chloroplasts: Site of photosynthesis, contains chlorophyll

Prokaryotic Cells

• Examples: Bacteria, Algae
• Features:
  • Flagellum: Tail for movement
  • Nucleoid: Area for DNA storage (no central nucleus)
  • Some contain chloroplasts for photosynthesis

Specialized Cells

Animal Cells

• Red Blood Cells

  • No nucleus, more space for oxygen
  • Bi-concave shape for efficient oxygen transport

• White Blood Cells

  • Irregular shape, engulfs bacteria/viruses

• Muscle Cells

  • Contains protein fibers, mitochondria for energy

• Sperm Cells

  • Tail for movement, acrosome to penetrate egg
  • Mitochondria for energy

Plant Cells

• Xylem Cells

  • Transport water/minerals using dead cells (passive)

• Phloem Cells

  • Transport glucose, use energy (active), contain mitochondria

• Root Hair Cells

  • Large surface area for water/mineral absorption
  • Mitochondria for active transport

Transport in Cells

Diffusion

• Passive process, no energy required
• Movement from high to low concentration
• Affects rate: concentration gradient, temperature

Osmosis

• Passive, involves water molecules
• Moves through a partially permeable membrane
• Achieves balance between concentrations

Active Transport

• Requires energy, mitochondria involved
• Moves substances against concentration gradient
• Example: Uptake of ions/minerals in root hair cells

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