UNIT 2

• Macromolecules


  Proteins, lipids, nucleic acids, carbohydrates
• Phospholipids


  • Have polar heads and nonpolar fatty acid tails
  • Membranes are bilayered with hydrophobic tails facing inward
• Ribosomes


  Made of rRNA and protein, found free-floating in cytoplasm and embedded on rough ER, primary role is protein production
• Components of the endomembrane system


  • Nuclear envelope
  • Lysosomes
  • Vesicles
  • Endoplasmic reticulum
  • Golgi apparatus
  • Plasma membrane
• Endoplasmic reticulum (ER)


  • Rough ER is involved in protein production and folding, smooth ER is involved in detoxification and lipid synthesis
• Golgi complex


  • Membrane-bound organelle that packages, processes, sorts and ships lipids and proteins
• Lysosome


  Organelle with hydrolytic enzymes involved in cell recycling and apoptosis
• Vacuole


  Sac-like organelle with a variety of roles depending on the cell type
• Mitochondria


  • Double membrane structure, inner membrane folded into cristae, performs cellular respiration and ATP production
• Chloroplast


  • Double membrane structure, inner thylakoid membranes and surrounding stroma, performs photosynthesis
• Mitochondria and chloroplasts are theorized to have formed from independent prokaryotes through endosymbiosis
• As cell size increases

  Volume increases faster than surface area
• Fluid mosaic model of plasma membrane


  Membrane has multiple components that are constantly in motion
• Passive transport


  Net movement of molecules from high to low concentration without using ATP
• Active transport


  Movement of molecules from low to high concentration, requires ATP
• Types of active transport


  • Membrane pumps
  • Endocytosis
  • Exocytosis
• Facilitated diffusion


  Passive movement of molecules through transport proteins
• Osmosis


  Passive diffusion of water across a semi-permeable membrane
• Hypertonic, hypotonic, isotonic


  Relative concentrations of solutes in solutions
• Vacuoles contribute to osmoregulation
• Cell types


  • Prokaryotes (bacteria, archaea)
  • Eukaryotes (protists, fungi, plants, animals)
• Prokaryotes are smaller, evolved earlier, lack a nucleus and membrane-bound organelles, have circular DNA
• Eukaryotes are larger, evolved later, have a nucleus and membrane-bound organelles, have linear DNA in chromosomes