Respiration

• why do we have a need to respire

  cells use ATP as their main energy source

  respiration transfers energy stored in organic molecules to ATP by phosphorylation which is then used for many cellular processes
• what requires the energy from respiration

  • active processes -> conduction of nervous impulses
  • muscle contraction
  • anabolic processes -> protein synthesis
• mitochondria

  • inner mitochondrial membrane space
  • outer and inner membranes
  • fluid filled matrix
  • ribosomes
  • loop of DNA
• outer mitochondrial membranes

  contain proteins that create channel and carrier proteins

  allow molecules to move into the inter-membrane space such as pyruvate
• inner mitochondrial membrane

  folded into cristae to increase surface area

  impermeable to small ions

  contain electron transport chains

  contains atp synthase enzymes
• cristae

  provide a large surface area

  allow for a chemiosmotic gradient to be established
• matrix

  link and krebs cycle

  70s ribosomes

  fluid filled
• mitochondrial DNA

  codes for enzymes and proteins
• glycolysis location

  cytoplasm

  aerobic process
• stages of glycolysis

  1. glucose -> 2 hexose bisphosphate (2ATP -> 2ADP)
  2. 2 hexose bisphosphate -> 2 triose phosphate
  3. 2 triose phosphate -> 2 pyruvate (4 ATP + 2 NADH+)
• link reaction

  only continues to link if oxygen is present

  mitochondrial matrix

  pyruvate enters by active transport which uses energy in the form of ATP
• link reaction stages

  1. decarboxylation of pyruvate -> acetate + CO2 + NADH+
  2. acetate + coenzyme A -> acetyl CoA
  3. net: 2 NADH+ and 2 CO2 per glucose molecule
• krebs cycle

  occurs twice per glucose molecule

  mitochondrial matrix
• krebs cycle stages

  1. acetyl CoA + oxaloacetate -> citrate
  2. citrate enters the krebs cycle
  3. citrate -> oxaloacetate (which is regenerated)
• net krebs cycle per molecule of glucose

  2 ATP

  6 NADH+

  4 FADH+

  4 CO2
• how is atp formed in the krebs cycle

  substrate level phosphorylation

  Pi + ADP -> ATP

  catalysed by kinases and phosphorylases
• importance of co enzymes made in the krebs cycle

  collect hydrogen atoms to provide a source of electrons and hydrogen ions in the electron transport chain to produce as many ATP molecules as possible
• importance of decarb and dehydrogenation in the krebs cycle

  regenerate oxaloacetate so it can re-bind with a new molecule of acetyl CoA

  removal of hydrogen atoms accepted by NAD and FAD
• importance of substrate level phosphorylation

  quicker source of ATP

  free energy required is provided by the chemical energy released when a higher energy substrate is converted into a lower energy product
• importance of NAD as a coenzyme

  hydrogen acceptor and carrier

  reduced in all but glycolysis

  increased efficiency of dehydrogenase enzymes
• FAD importance

  hydrogen carrier

  reduced in krebs only
• CoA importance

  carries an acetyl group from the links to krebs
• oxidative phosphorylation

  cristae membrane
• chemiosmotic theory


  NADH and FADH release hydrogen atoms

  these dissociate into H+ and e-

  high energy electrons released energy as they move down the electron transport chain which allows hydrogen ions to be actively transported into the inter membrane space from the matrix creating an chemiosmotic gradient

  facilitative diffusion down ATP synthase channel protein generates a proton motive force which drives ADP + Pi -> ATP
• role of oxygen

  final electron acceptor

  2 H+ + 2 e- + O2 -> H2O
• issue with H+ build up in the IMS

  acidity increases

  ph decreases

  proteins such as ATP synthase denature
• chemiosmotic theory definition

  diffusion of hydrogen ions across a partially permeable membrane down their electrochemical gradients
• anaerobic in mammals

  cytoplasm of cells

  pyruvate -> lactate (NADH -> NAD)

  in the liver lactate -> pyruvate
• net anaerobic in mammals

  loss of 4 ATP (uses 6 ATP)
• yeast anaerobic

  pyruvate -> ethanal (CO2)

  ethanal -> ethanol (NADH -> NAD)

  irreversible

  NAD goes back to glycolysis
• why lower yield in anaerobic

  net gain of 2 ATP as only in glycolysis

  whereas ETC can produce 34 ATP
• triglyceride respiratory quotient

  39.4

  glycerol -> pyruvate (enter link)

  3 fatty acids -> 50 acetyl CoA ~ 500 ATP
• protein respiratory quotient

  17

  amino acid -> deamination into pyruvate (uses ATP)

  ~ loose muscle mass
• carbohydrate respiratory quotient 


  15.8
• why do lipids have the highest mean energy value

  more H atoms -> more ATP made
• RQ equation

  CO2 produced / oxygen consumed
• RQ values

  carb -> 0.1

  lipid -> 0.7

  protein -> 0.9
• net ATP of NADH

  3
• net ATP of FADH

  2