Prokaryotic and Eukaryotic Cells

• The cell membrane is the outer boundary of a cell, made up of a lipid bilayer with hydrophilic heads facing outward and hydrophobic tails facing inward

  
• The cell membrane acts as a barrier between the cell and its environment, allowing the passage of some molecules like oxygen and carbon dioxide through diffusion
• Prokaryotic cells are the simplest type of cells found in bacteria, lacking a nucleus and membrane-bound organelles
• Prokaryotic cells have a cell wall made of peptidoglycan, a cell membrane, cytoplasm, ribosomes, plasmids, flagellum, and pili
• Flagellum is made of the protein flagellin, has a helical shape with a sharp bend, and is used for locomotion
• Fimbriae and pili are structures used for attachment to surfaces, with pili being longer than fimbriae and used for conjugation between prokaryotic cells
• The glycocalyx in bacteria serves as a reservoir for nutrients and protection from environmental changes, existing as a capsule or slime layer
• The cell wall of bacteria, except mycoplasmas, contains peptidoglycan, with gram-positive bacteria having more peptidoglycan and gram-negative bacteria having more lipids
• Gram staining differentiates bacteria based on cell wall composition, with crystal violet staining both types purple, iodine forming complexes, alcohol dehydrating Gram-positive bacteria, and safranin coloring Gram-negative cells red or pink
• Cytoplasm in prokaryotic cells contains water, proteins, carbohydrates, lipids, inorganic ions, ribosomes, nucleoid, plasmids, and endospores
• Prokaryotic cells reproduce asexually through binary fission or budding, with some forming endospores when nutrients are depleted