A2 Biology - Respiration

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  • Created by: dom
  • Created on: 05-01-15 12:00

2 DIFFERENT FORMS OF RESPIRATION

AEROBIC RESPIRATION - REQUIRES O2 AND PRODUCES CO2, WATER AND LOTS OF ATP.

ANAEROBIC RESPIRATION - TAKES PLACE IN ABSENCE OF O2, PRODUCES LACTATE IN ANIMALS OR ETHANOL AND CO2 IN PLANTS - BUT ONLY A SMALL AMOUNT OF ATP

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4 STAGES OF RESPIRATION

  1. GLYCOLYSIS - SPLITTING OF GLUCOSE IN TO TWO 3 CARBON PYRUVATES 
  2. LINK REACTION - COVERSION OF PYRUVATE TO ACETYL COENZYME A 
  3. KREBS CYCLE - INTRO OF ACETYL COENZYME A INTO A CYCLE OF REDOX REACTIONS
  4. ETC - THE USE OF THE ELECTRONS PRODUCED IN KREBS TO SYNTHESISE ATP WITH WATER 
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GLYCOLYSIS

INITIAL STAGE IN BOTH AEROBIC AND ANAEROBIC RESPIRATION 

OCCURS IN CYTOPLASM OF CELLS 

  • ACTIVATION OF GLUCOSE BY PHOSPHORYLATION - glucose is unreactive, 2 phosphates must be added - from the hydrolysis of ATP TO ADP to make it more reactive 
  • SPLITTING OF THE PHOSPHORYLATED GLUCOSE - glucose is split into two 3 carbon molecules known as TP
  • OXIDATION OF TP - hydrogen is removed from each TP molecule and transferred to NAD to make NADH.
  • PRODUCTION OF ATP - anzyme controlled reactions convert each TP into PYRUVATE - in this process 2 molecules of ATP ARE REGENERATED FROM ADP 
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ENERGY YIELD FROM GLYCOLYSIS

  • 2 MOLECULES OF ATP 
  • 2 MOLECULES OF NADH 
  • 2 MOLECULES OF PYRUVATE 
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LINK REACTION

TAKES PLACE IN MITOCHONDRIA 

  • PYRUVATES ARE ACTIVLEY TRANSPORTED FROM CYTOPLASM TO MATRIX OF MITOCHONDRIA 
  • HERE PYRUVATE IS OXIDISED BY REMOVING HYDROGEN 
  • HYDROGEN IS ACCEPTED BY NAD TO MAKE NADH 
  • AN ACETYL GROUP IS FORMED 
  • THE ACETYL GROUP COMBINES WITH COENZYME A TO PRODUCE ACETLY COENZYME A
  • CO2 IS PRODUCED FROM EACH PYRUVATE 

EQUATION 

PYRUVATE + NAD + COA = ACETYL COA + NADH + CO2

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KREBS CYCLE

INVOLVES A SERIES OF OXIDATIONA ND REDUCTION REACTIONS

TAKES PLACE IN MATRIX OF THE MITOCHONDRIA 

  1. 2 CARBON ACETYL COENZYME A COMBINES WITH A 4 CARBON COMPOUND (CITRIC ACID) TO MAKE A 6 CARBON COMPOUND 
  2. 6 CARBON MOLECULE LOSES CO2 AND HYDROGEN TO GIVE A 4 CARBON MOLECULE AND ATP IS PRODUCE AS A RESULT OF SUBSTRATE LEVEL PHOSPHORYLATION 
  3. COENZYMES NAD AND FAD COMBINE WITH HYDROGEN TO REDUCE THEM 
  4. THE 4 CARBON COMPUND IS REUSUED IN CYCLE 

ENERGY YIELD 

  • 2 ATP 
  • 6 NADH 
  • 2 FADH 
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IMPORTANCE OF KREBS CYCLE

  • BREAKS DOWN MACROMOLECULES INTO SMALLER ONES E.G. PYRUVATE TO CO2 
  • PRODUCES HYDROGEN ATOMS - CARRIED BY COENZYMES NAD OR FAD TO ETC - LEADS TO PRODUCTION OF ATP
  • REGENERATES 4 CARBON COMPOUNT - CITRIC ACID
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ELECTRON TRANSPORT CHAIN

MITOCHONDIRA SITE OF ETC 

ATTATCHED TO THE CRISTAE - INNER FOLDING MEMBRANE - ARE ENZYMES AND OTHER PROTEINS INVOLVED IN ETC

  1. NADH AND FADH BRING HYDROGEN ATOMS TO ETC - THEY SPLIT INTO PROTONS AND ELECTRONS 
  2. NADH AND FADH DONATE ELECTRONS OF THE HYDROGEN ATOMS TO FIRST MOLECULE OF ETC 
  3. THIS RELEASES THE PROTONS FROM THE HYROGEN - THEY ARE ACTIVELY TRANSPORTED ACROSS INNER MITOCHONDRIAL MEMEBRANE INTO INTERMEMBRANE SPACE 
  4. THE ELECTRONS MEANWHILE PASS ALONG ETC - SERIES OF REDOX REACIONS - ENERGY LOST IS USED TO FORM ATP FROM ADP
  5. THE PROTONS THEN DIFFUSE BACK INTO THE MITOCHONDRIAL MATRIX THROUGH PROTEIN CHANNELS CALLED ATP SYNTHASE - CONCENTRATON GRADIENT - CHEMIOSOMOSIS 
  6. THEY JOIN UP WITH THE ELECTRONS AND OXYGEN TO FORM WATER 
  7. OXYGEN IS THE FINAL ELECTRON ACCEPTOR 

Chemiosmosis is the movement of ions across a selectively permeable membrane, down their electrochemical gradient. More specifically, it relates to the generation of ATP by the movement of hydrogen ions across a membrane during cellular respiration or photosynthesis

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ANAEROBIC RESPIRATION

ONLY GLYCOLYISIS CAN OCCUR IN ABSENCE OF OXYGEN 

IN PLANTS - PYRUVATE IS CONVERTED TO ETHANOL AND YEAST 

IN ANIMALS - PYRUVATE IS CONVERTED TO LACTIC ACID 


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ANAEROBIC RESPIRATION - PLANTS

PYRUVATE + REDUCED NAD = ETHANOL + CO2 + NAD 

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ANAEROBIC RESPIRATION - ANIMALS

PYRUVATE + REDCUED NAD = LACTATE + NAD 

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