Starter When is the majority of ATP produced in respiration??? HOW? What conclusion can you make about the best respiratory substrate?

Starter: Oxidative phosphorylation Protons flow through channels associated with ATP synthase on inner mitochondrial membrane The more protons=more ATP produced! So more protons in respiratory substrate= more TP when the substrate is respired More H atoms per mole of substrate= more oxygen (final acceptor) needed to respire the substrate!

Respiratory Substrates: LO Define the term respiratory substrate; Explain the difference in relative energy values of carbohydrate, lipid and protein So define …… A respiratory substrate is an organic substance that can be used for respiration

Draw a glucose molecule! How many hydrogens!

Glucose (C6H12O6) C1 O C2 C3 C4 C5 C6H2OH H OH H C1 C2 C3 O H OH HO H Ring Chain Chain form

Carbohydrates Glucose is the most common substrate for most mammalian cells Animals store glucose as glycogen, and plants as starch Theoretical maximum energy yield for one mole of glucose is 2870 kJ It takes 30.6 kJ to produce 1 mol ATP Respiration of 1 mol glucose should produce nearly 94 mol ATP, but the actual yield is more like 30, as it has an efficiency of 32% Remaining energy used to generate heat Maintains suitable temperature for all the enzyme controlled reactions

Proteins Draw the amino acid glycine R=H How many hydrogens??

Proteins: Amino acids: 5 H OH H H

Protein Excess amino acids are deaminated (removal of amine group converted to urea) Rest is changed to glycogen or fat During fasting/starvation /prolonged exercise: Protein is then hydrolysed (split with water) to amino acids which can be respired Some can be converted to pyruvate, or acetate and then is carried to Krebs cycle Some can enter Krebs directly Number of hydrogen atoms per mole accepted by NAD then used in electron transport chain is slightly more than the number of hydrogen atoms per mole of glucose, so proteins release slightly more energy than equivalent masses of glucose

How amino acids enter the Krebs cycle:

Draw a triglyceride molecule Draw a glycerol molecule How many hydrogen's????

Lipids: triglycerides Lipids are formed by joining fatty acids to a glycerol backbone. Glycerol molecule is same in all fats, so it is the fatty acid that gives fats their different properties C O C17H35 HO H CARBOXYL GROUP (acid) H C OH C O C17H35 HO H C OH O H C OH HO C C17H35 H Condensation reaction: Acid group on fatty acid + OH Hydroxyl group of glycerol =Covalent bond= ester bond Glycerol (C3H8O3)

Hydrolysis of triglycerides: Palmitic acid: a fatty acid

Lipids Made of fatty acids and glycerol Glycerol can be converted to glucose, fatty acids can’t Contain many carbon atoms and hydrogen atoms SO SOURCE OF MANY PROTONS= Much ATP! What happens to the fatty acids??

ATP produced by chemiosmosis Fatty acids combined with CoA after ATP hydrolysed (split using water) to AMP (adenosine monophosphate) + 2 Pi Fatty acid CoA complex taken to matrix and broken down into 2- carbon acetyl groups that are attached to CoA Reduced NAD and FAD are formed Acetyl groups are released from CoA and enter Krebs producing 3 NADH, 1 FADH and 1 ATP (slp) NADH can then go to electron transport chain ATP produced by chemiosmosis

Fatty Acid Coenzyme A Fatty Acid Coenzyme A complex NAD + FAD Reduced NAD + FAD Many 2-carbon acetyl groups Coenzyme A 2-carbon acetyl groups go to the Krebs Cycle

Mean energy values per gram of respiratory substrate Mean energy value/kJ g-1 Carbohydrate Lipid Protein Guess??

Mean energy values per gram of respiratory substrate Mean energy value/kJ g-1 Carbohydrate 15.8 Lipid 39.4 Protein 17.0

Respiratory Quotients (RQ) It is sometimes useful to be able to deduce which substrate is being used in a person’s metabolism at a specific time. This can be done if the volume of oxygen taken in, and the volume of carbon dioxide given out are measured. The respiratory quotient (RQ) is the ratio of the volume of oxygen absorbed and carbon dioxide given off in respiration RQ = Volume of carbon dioxide given off Volume of oxygen used per unit of time

Calculate RQ Calculate the RQ for the aerobic respiration of Glucose. 1 Carbohydrates have RQ of 1 Calculate the RQ for the fatty acid oleic acid, when respired aerobically. C18H34O2+ 25.5O2  18 CO2 + 17 H2O 0.71 Usual RQ value for lipids

Calculating RQ for Anaerobic respiration C6H12O6  2C2H5OH + 2CO2 A high RQ value suggests that anaerobic respiration is taking place. No RQ can be calculated for the lactate pathway as no carbon dioxide is given off.

Respiratory Quotients (RQ) The respiratory quotients of different respiratory substrates are well documented from previous investigations. Carbohydrate 1.0 Protein 0.9 Fat 0.7 It is possible to deduce which substrate is being used by the metabolism at a specific time. NB if a mixture of substrates is being used then the figure will be different from those above.

Respiratory Quotients (RQ) The respiratory quotients of different respiratory substrates are well documented from previous investigations. Carbohydrate 1.0 Protein 0.9 Fat 0.7 It is possible to deduce which substrate is being used by the metabolism at a specific time. NB if a mixture of substrates is being used then the figure will be different from those above.

Finished theory!! JUST HSW to go!! Task: Ensure your notes are clear for the LO. Exam question in booklet: RQ: Some animals conserve energy (3)