C1.2 + C1.3

• ATP


  The energy released by the breaking of the phosphate bonds is the high energy bonds of ATP which carries out cellular work
• Life processes within cells


  • Require ATP
  • Include synthesis of macromolecules by anabolism
  • Movement of whole cell by cilia or flagellum
  • Movement within cell of cell components like chromosome movement in mitosis or meiosis
• ATP synthesis


  Requires energy
• Energy that synthesizes ATP from ADP and phosphate


  Stored between the second and third phosphate groups
• Endergonic reaction


  Input of energy (like condensation)
• Exergonic reaction


  Output of energy (like hydrolysis)
• Cellular respiration


  1. Glucose oxidizes into CO2

  2. Oxygen reduces into H2O

  
• Glucose entry into cell

  Through the cell membrane, found in the cytoplasm

  
• Glycolysis


  1. Enzyme catalyze 6-carbon glucose into 2 molecules of 3-carbon glucose called Pyruvate

  2. 2 ATP molecules required to start

  3. Total of 4 ATP molecules formed, net gain of 2 ATPs

  
• Anaerobic glycolysis


  Common to most organisms, can occur without oxygen causing alcoholic or lactic acid fermentation

  
• Anaerobic fermentation in humans

  Lactic acid fermentation
• Aerobic respiration


  1. Pyruvates enter the mitochondrion

  2. Pyruvates turned into 2-carbon compound to enter Krebs cycle (in mitochondrial matrix)

  3. Link reaction occurs in mitochondrial matrix

  4. Krebs cycle has net gain of 2 ATPs

  5. Electron transport chain takes place in mitochondrial cristae, produces around 30-34 ATPs

  
• Summary of anaerobic cell respiration

  • Does not require oxygen but requires glucose
  • Occurs in the cytoplasm
  • Splits into pyruvate
  • If no oxygen, turns into lactic acid (in humans) in the cytoplasm
  • No mitochondria required
  • Net gain of two ATPs

  
• Summary of aerobic cell respiration

  • Requires oxygen and glucose
  • Begins in the cytoplasm
  • Two molecules of pyruvate split into 3 molecules of 2 carbon sugars (in the matrix)
  • If enough oxygen, pyruvate moves to matrix of mitochondria
  • 2-carbon compound enters the Krebs cycle in the matrix
  • 3034 ATPs produced in the cristae of the mitochondria (Electron transport chain)
  • Final products are CO2, H2O and ATP

  
• Factors affecting rate of cell respiration


  • Temperature (ideal 20-30 Celsius)
  • CO2 concentration (increase affects adversely)
  • Oxygen concentration (lower O2 decreases rate)
  • Glucose concentration (low levels decrease rate)
  • Type of cell (some require more energy than others)

  
• Oxidation


  Loss of electrons, gain of oxygen, loss of hydrogen, results in many C=O bonds, results in a compound with lower potential energy
• Reduction


  Gain of electrons, loss of oxygen, gain of hydrogen, results in many C-H bonds, results in a compound with higher potential energy

  
• NAD


  A coenzyme used by the enzymes of cell respiration

  
• NAD reduction and oxidation

  NAD + H = NADH (reduction)

  NADH = NAD + H (oxidation)
• Glycolysis step 1


  Two molecules of ATP are used to phosphorylate glucose into fructose 1,6 biphosphate

  
• Glycolysis step 2


  Fructose 1,6 biphosphate is split into two 3-carbon sugars triose phosphate

  
• Glycolysis step 3


  Each triose phosphate undergoes oxidation to form NADH, released energy is used to add inorganic phosphate to the remaining 3-carbon compound, enzymes remove the phosphate group to produce ATP
• Glycolysis produces 4 ATP molecules, two molecules of NADH and two pyruvate molecules

  
• Pyruvate fate


  If oxygen present, enters mitochondria for aerobic respiration

  If oxygen not present, stays in cytoplasm for anaerobic respiration (converted to lactate in animals/humans or ethanol in plants)

  
• Regeneration of NAD is important because without it, glycolysis would have to stop
• Anaerobic respiration in yeast

  2 molecules of pyruvate turn into 2 molecules of 2-carbon ethanol, CO2 is released as a waste product

  
• Bakers yeast is added to bread products because yeast takes glucose from environment and produces CO2 to help make the bread rise
• Link reaction


  Pyruvate enters mitochondrial matrix

  Pyruvate is decarboxylated to form 2-carbon acetyl group, CO2 is released as waste product

  Acetyl group combines with coenzyme A to form Acetyl-CoA

  Acetyl-CoA enters the Krebs cycle

  
• Acetyl groups are formed and produced from carbohydrates and lipids
• Krebs cycle


  Occurs in mitochondrial matrix

  Includes two decarboxylation reactions and four points of carbon compound oxidation for each acetyl group

  Produces 2 ATP, 6 NADH, 2 FADH2, 4 CO2

  
• Krebs cycle runs twice per glucose molecule

  
• Decarboxylation


  Chemical reaction that removes a carboxyl group and releases CO2, H+ ion is used to reduce compounds like NAD
• Electron transport chain


  NADH transfers high energy electrons to first carrier

  Electrons transferred from one carrier to another with small energy releases

  Protons pumped across inner mitochondrial membrane, creating proton gradient

  Protons flow back through ATP synthase, driving ATP production

  
• Electron transport chain occurs on inner mitochondrial membrane and cristae membranes, which contain electron carrier molecules

  
• Electron transport chain


  1. Electrons move down the chain

  2. Energy is released in small amounts and used to pump protons from matrix to intermembrane space

  3. Creates a proton gradient with high concentration in intermembrane space
• Chemiosmosis


  1. Protons move down concentration gradient through ATP synthase

  2. ATP synthase uses energy to phosphorylate ADP to form ATP
• Oxygen


  • Final electron acceptor
  • Combines with electrons and hydrogen ions from matrix to form water of metabolism
• Respiratory substrates


  • Lipids yield 20% more ATP than carbohydrates
  • Carbohydrates required for full glycolysis and anaerobic respiration
• Photosynthesis


  CO2 + water ---> (light) glucose + oxygen

  
• Photosynthetic pigments


  • Contained in chloroplasts
  • Chlorophyll a and b are most common
  • Carotenoids are carotenes and xanthophyll