Chapter 5,6,7 Bio

• Cell membranes


  • Composed of lipids and proteins

  
• Phospholipids


  Amphipathic molecules with hydrophilic and hydrophobic regions
• Phospholipid bilayer formation


  Amphipathic property of phospholipids

  
• Cholesterol


  • Major component of cell membranes, associated with phospholipid bilayers
• Selective permeability


  Results from the combination of lipids and proteins that make up cell membranes

  
• Passive transport


  Diffusion, the random movement of molecules from higher to lower concentration
• Passive transport


  Can occur through the plasma membrane (simple diffusion) or be aided by protein channels (facilitated diffusion)
• Active transport


  Moves molecules from lower to higher concentration, requires energy
• Active transport


  Uses energy stored in ATP
• Prokaryotic and eukaryotic cells

  • Differ in the degree of internal compartmentalization (nucleus and other internal membrane-enclosed compartments)
• Eukaryotic cell organelles


  • Nucleus
  • Endoplasmic reticulum
  • Golgi apparatus
  • Lysosome

  
• Endoplasmic reticulum


  Manufactures proteins and lipids for use by the cell or for export
• Rough endoplasmic reticulum


  Involved in protein synthesis

  
• Smooth endoplasmic reticulum


  Involved in lipid synthesis

  
• Golgi apparatus


  Communicates with the ER via transport vesicles, receives proteins and lipids from the ER and directs them to their final destinations
• Lysosomes


  Specialized vesicles that degrade damaged or unneeded macromolecules
• Mitochondria


  Harness energy from chemical compounds for use by both animal and plant cells
• Chloroplasts


  Present only in plant cells, harness the energy of sunlight to build sugar
• Energy


  Can take the form of chemical energy or other forms, e.g. heat
• ATP


  Contains chemical energy in its bonds
• Exergonic reaction


  Releases energy, results in products with lower potential energy
• Endergonic reaction


  Requires energy input, results in products with higher potential energy
• Hydrolysis of ATP


  Can drive non-spontaneous reactions in a cell (coupled reaction)
• Oxidation


  Losing electrons
• Reduction

  Gaining electrons
• Breakdown of glucose in the presence of oxygen to produce carbon dioxide is an example of an oxidation-reduction reaction

  
• The overall balanced chemical equation for cellular respiration, noting the starting and ending products, energy-storing molecules that are produced, and what molecules are oxidized and reduced
• Organic molecules


  Have more potential energy if they have more C-H bonds
• Stages of cellular respiration

  • Glycolysis
  • Pyruvate oxidation
  • Citric acid cycle
  • Oxidative phosphorylation
• Glycolysis


  Occurs in the cytoplasm, breaks down glucose into pyruvate, produces ATP and electron carriers

  
• Pyruvate oxidation


  Occurs in the mitochondrial matrix, converts pyruvate into acetyl CoA, generates more electron carriers

  
• Citric acid cycle


  Also known as the Krebs cycle, occurs in the mitochondrial matrix, further breaks down acetyl CoA, produces ATP, electron carriers, and CO2

  
• Oxidative phosphorylation / electron transport chain


  Occurs in the inner mitochondrial membrane, electron carriers donate electrons to the electron transport chain, generating a proton gradient used to produce ATP via ATP synthase

  
• Oxygen serves as the final electron acceptor in the electron transport chain during aerobic respiration, its presence is crucial for the efficient production of ATP via oxidative phosphorylation
• Anaerobic respiration


  Occurs in the absence of oxygen, generates less ATP than aerobic respiration
• Cell membrane composition


  Structure and makeup of cell membranes (lipids and proteins)

  
• Phospholipids


  Main lipid component forming a lipid bilayer, composed of a hydrophilic phosphate head and two hydrophobic fatty acid tails, spontaneously arrange into a lipid bilayer due to their amphipathic nature

  
• Micelle


  Structure formed by hydrophobic compounds like cholesterol when encountering an aqueous environment, with the hydrophobic molecules aggregating in the center shielded by the hydrophilic heads of surrounding phospholipids
• Cholesterol


  A lipid molecule found in cell membranes, particularly in animal cells, plays an important role in maintaining membrane fluidity and stability, interspersed among phospholipids in the lipid bilayer

  
• Membrane permeability


  Small nonpolar or uncharged polar molecules can pass through, larger polar molecules and ions require transport proteins