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Chapter 49.4, 7.6 Cellular Respiration: Gas Exchange, Other Metabolites & Control of Respiration ATP.

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Presentation on theme: "Chapter 49.4, 7.6 Cellular Respiration: Gas Exchange, Other Metabolites & Control of Respiration ATP."— Presentation transcript:

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2 Chapter 49.4, 7.6 Cellular Respiration: Gas Exchange, Other Metabolites & Control of Respiration ATP

3 Cellular Respiration

4 Gas Exchange  O 2 & CO 2 exchange  provides O 2 for aerobic cellular respiration  exchange between environment & cells  need high surface area  need moist membrane Respiration for respiration…

5 Optimizing Gas Exchange  Why high surface area?  maximizing rate of gas exchange  CO 2 & O 2 move across cell membrane by diffusion  rate of diffusion proportional to surface area  Why moist membranes?  moisture maintains cell membrane structure  gases diffuse only dissolved in water High surface area? High surface area! Where have we heard that before?

6 Gas Exchange in Many Forms… endotherm vs. ectotherm size water vs. land one-celled amphibians echinoderms insects fish mammals

7  Exchange surface, but also creates risk:  entry point for environment into body  Exchange surface, but also creates risk:  entry point for environment into body Lungs spongy texture, honeycombed with moist epithelium

8 Alveoli  Gas exchange across thin epithelium of millions of alveoli  total surface area in humans ~75 m 2

9 Diffusion of Gases  Concentration & pressure drives movement of gases into & out of blood at both lungs & body tissue bloodlungs CO 2 O2O2 O2O2 bloodbody CO 2 O2O2 O2O2 capillaries in lungscapillaries in muscle

10 Hemoglobin  Why use a carrier molecule?  O 2 not soluble enough in H 2 O for animal needs  blood alone could not provide enough O 2 to animal cells  hemocyanin in insects = copper (bluish)  hemoglobin in vertebrates = iron (reddish)  Reversibly binds O 2  loading O 2 at lungs or gills & unloading at cells cooperativity heme group

11 Cooperativity in Hemoglobin  Binding O 2  binding of O 2 to 1 st subunit causes shape change to other subunits  conformational change  increasing attraction to O 2  Releasing O 2  when 1 st subunit releases O 2, causes shape change to other subunits  conformational change  lowers attraction to O 2

12 O 2 Dissociation Curve for Hemoglobin Bohr Shift  drop in pH lowers affinity of Hb for O 2  active tissue (producing CO 2 ) lowers blood pH & induces Hb to release more O 2 P O 2 (mm Hg) 0 10 20 30 40 50 60 70 80 90 100 020406080100120140 More O 2 delivered to tissues pH 7.60 pH 7.20 pH 7.40 % oxyhemoglobin saturation Effect of pH (CO 2 concentration)

13 O 2 Dissociation Curve for Hemoglobin P O 2 (mm Hg) 0 10 20 30 40 50 60 70 80 90 100 020406080100120140 More O 2 delivered to tissues 20°C 43°C 37°C % oxyhemoglobin saturation Effect of Temperature  increase in temperature lowers affinity of Hb for O 2  active muscle produces heat

14 Fetal Hemoglobin (HbF) What is the adaptive advantage? 2 alpha & 2 gamma units  HbF has greater attraction to O 2 than Hb  low O 2 % by time blood reaches placenta  fetal Hb must be able to bind O 2 with greater attraction than maternal Hb

15 Beyond glucose: Other carbohydrates  Glycolysis accepts a wide range of carbohydrates fuels  polysaccharides    glucose  ex. starch, glycogen  other 6C sugars    glucose  ex. galactose, fructose hydrolysis modified

16  proteins      amino acids Beyond glucose: Proteins hydrolysis amino group = waste product excreted as ammonia, urea, or uric acid carbon skeleton = enters glycolysis or Krebs cycle at different stages N H H C—OH || O H | —C— | R waste glycolysis Krebs cycle

17 Beyond glucose: Fats  Fats      glycerol & fatty acids  glycerol (3C)   DHAP   glycolysis  fatty acids  hydrolysis 2C acetyl groups  acetyl coA  Krebs cycle enters glycolysis as DHAP glycerol enter Krebs cycle as acetyl CoA fatty acids

18 Carbohydrates vs. Fats fat carbohydrate  Fat generates 2x ATP vs. carbohydrate  more C in gram of fat  more O in gram of carbohydrate  so it’s already partly oxidized Check the energy per gram listings on the Nutritional Fact sheet on all foods

19  Coordination of digestion & synthesis  by regulating enzyme  Digestion  digestion of carbohydrates, fats & proteins  all catabolized through same pathways  enter at different points  cell extracts energy from every source Metabolism CO 2

20 Metabolism Krebs cycle intermediaries    amino acids pyruvate   glucose acetyl CoA   fatty acids  Coordination of digestion & synthesis  by regulating enzymes  Synthesis  enough energy? build stuff!  cell uses points in glycolysis & Krebs cycle as links to pathways for synthesis  run the pathways “backwards”  eat too much fuel, build fat Cells are versatile & thrifty

21 Carbohydrate Metabolism  The many stops on the “Carbo Line” gluconeogenesis

22 Lipid Metabolism  The many stops on the “Lipid Line”

23 Amino Acid Metabolism  The many stops on the “AA Line”

24 Nucleotide Metabolism  The many stops on the “GATC Line”

25 What – rather – where is this??? Can you tell me which way to The Mitre? I’m looking for a good pint of bitter! Name the city in 10 seconds to earn Sheldon’s respect!

26 Control of Respiration Feedback Control of Cellular Respiration

27 G is an allosteric inhibitor of enzyme 1 Feedback Inhibition  Regulation & coordination of production  production is self-limiting  final product is inhibitor of earlier step  allosteric inhibitor of earlier enzyme  no unnecessary accumulation of product A  B  C  D  E  F  GA  B  C  D  E  F  G enzyme 1  enzyme 2  enzyme 3  enzyme 4  enzyme 5  enzyme 6  X

28 Respond to cell’s needs Why is this regulation important? Balancing act: availability of raw materials vs. energy demands vs. synthesis  Key points of control  phosphofructokinase  allosteric regulation of enzyme  “can’t turn back” step before splitting glucose  ↑ [AMP] & [ADP] stimulate (activators)  ↑ [ATP] inhibits  ↑ [citrate] inhibits

29 A Metabolic Economy  Basic principles of supply & demand regulate metabolic economy  balance the supply of raw materials with the products produced  these molecules become feedback regulators  they control enzymes at strategic points in glycolysis & Krebs cycle  AMP, ADP, ATP regulation by final products & raw materials  levels of intermediates compounds in the pathways regulation of earlier steps in pathways  levels of other bio-molecules in body regulates rate of siphoning off to synthesis pathways

30 It’s a Balancing Act  Balancing synthesis with availability of both energy & raw materials is essential for survival!  do it well & you survive longer  you survive longer & you have more offspring  you have more offspring & you get to “take over the world” Acetyl CoA is central to both energy production & synthesis make ATP or store it as fat Acetyl CoA is central to both energy production & synthesis make ATP or store it as fat The world is mine! NERDS EVERYWHERE! BWAHAHAHA!

31 Any Questions?? That wasn’t such a bad chapter now, was it? It’s not like we will ever see it again. Weeeeelllllllll… Actually, don’t quote me on that.


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