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Cell Types

• Prokaryotic Cells

  • Lack a true nucleus and membrane-bound organelles.

• Eukaryotic Cells

  • Have a distinct nucleus and membrane-bound organelles.

Cell Membrane Composition

• Primarily composed of a phospholipid bilayer.

Membrane Channels

• Types

  • Proteins that facilitate the movement of ions and molecules across the membrane.

• Function

  • Regulate what enters and exits the cell, contributing to selective permeability.

Phospholipid Structure

• Regions of Phospholipid

  • Hydrophilic (water-attracting) heads and hydrophobic (water-repelling) tails.

• Functionality

  • The bilayer arrangement allows for a semi-permeable barrier, enabling selective movement of substances.

Lipid Bilayer Parts

• Hydrophilic Heads

  • Face outward toward the water, exposing the polar regions.

• Hydrophobic Tails

  • Face inward, away from water, providing a barrier to most water-soluble substances.

Selective Permeability

• The ability of the cell membrane to allow certain substances to pass while blocking others.

Major Cell Structures and Functions

1. Nucleus

   • Contains genetic material (DNA) and controls cell activities.

2. Mitochondria

   • Generate energy (ATP) through cellular respiration.

3. Lysosomes

   • Contain digestive enzymes to break down waste materials and cellular debris.

4. Centrioles

   • Involved in cell division and the formation of cilia and flagella.

5. Ribosomes

   • Synthesize proteins by translating messenger RNA.

6. Endoplasmic Reticulum (ER)

   • Rough ER: Synthesizes proteins; Smooth ER: Synthesizes lipids and detoxifies.

7. Golgi Apparatus

   • Modifies, sorts, and packages proteins and lipids for secretion or use within the cell.

8. Chloroplasts

   • Site of photosynthesis, converting light energy into chemical energy.

9. Vacuoles and Vesicles

   • Store substances, help in transport and maintaining turgor pressure in plant cells.