2/13/2012 Fat and Protein Metabolism
advertisement
2/13/2012 Break down of large Molecules to simple molecules Break down simple molecules to Acetyl CoA Fat and Protein Metabolism Oxidation of Acyetl CoA to H20 and CO2 – produce Eand make ATP 5-31 Fats and Proteins as Energy Sources Break down of large Molecules to simple molecules Fats can be hydrolyzed to glycerol and fatty acids can be modified to run through Kreb’s! Proteins can be broken down to amino acids Which can be deaminated and run through Kreb’s! These pathways can be used to interconvert carbohydrates, fats, and proteins Break down simple molecules to Acetyl CoA These Oxidation of Acyetl CoA to H20 and CO2 – produce Eand make ATP 5-32 Review Pyruvic acid from glycolysis Glucose Glycolysis Carbon atom Phase 1 priming Krebs cycle P Phosphate 2 Electron transport chain and oxidative phosphorylation ATP ATP 2 ADP ATP CO2 CoA Acetyl CoA Cytosol NAD+ NADH+H+ Mitochondrion (fluid matrix) ATP Fructose-1,6-diphosphate P Phase 2 cleavage P Dihydroxyacetone phosphate Glyceraldehyde phosphate Glyceraldehyde phosphate P P P Phase 3 oxidation and formation of ATP and release of high energy electrons 1 NAD+ 2 ADP 1 NADH + H+ 2 ATP 1 Pyruvic acid 1 Pyruvic acid O2 O22 O 2 NADH + H+ Key: 2 NAD+ = Carbon atom To citric acid cycle and electron transport chain (aerobic pathway) 2 Lactic acid Pi = Inorganic phosphate CoA = Coenzyme A 5 Figure 24.7 1 2/13/2012 Lipids - Triglycerides Acetyl CoA Is Formed by a common substrate for energy and other pathways condensation of 1 glycerol and 3 fatty acids Many are reversible reactions 5-34 2-36 Energy Storage Fat Synthesis (Lipogenesis) Acetyl When more CoAs (2Cs) can be linked together to form fatty acids Fatty acids + glycerol = Fat (triglycerides) Occurs mainly in adipose and liver tissues Fat is major form of energy storage in body Yields 9 kilocalories/g Carbos and proteins yield only 4 kc/g Body Energy 80 - 85% energy in a body is stored as fat - Some as Glycogen (Muscles mainly & liver) - 15-20% protein (not used much) energy is taken in than consumed, ATP synthesis is inhibited Glucose converted into 1) glycogen 2) fat 5-33 5-35 Lipogenesis and Lipolysis Pathways Lipolysis Glucose Is Glucose 6-phosphate Glycerol Stored triglycerides Fatty acids Glycerol produces a few ATP Released into blood - Liver converts most to Glucose (gluconeogenesis) 2. Free fatty acids serve as major energy source for many tissues (Acetyl CoA!!!!) 1. Glycerol Beta oxidation Pyruvic acid Fatty acids Acetyl groups - New triglycerides Acetyl-Co A Ketone bodies β-hydroxybutyric acid Acetoacetic acid Acetone breakdown of fat into fatty acids and glycerol hydrolysis by lipase Via PGAL (phosphoglyceraldehyde) Citric acid cycle Key 1 Glycerol = 1 pyruvic acid = ATP? Lipogenesis Lipolysis 26-11 5-36 2 2/13/2012 Beta-Oxidation of a Fatty Acid Lipogenesis and Lipolysis Pathways Beta-oxidation Glucose clips 2 C acetic Acid CoA to enter Krebs Which can be run thru Kreb’s giving 10 ATPs each Plus -oxidation itself yields 4 ATPs Glucose 6-phosphate Glycerol Leaves PGAL (phosphoglyceraldehyde) Stored triglycerides Fatty acids Glycerol Beta oxidation Pyruvic acid Fatty acids Acetyl groups New triglycerides Acetyl-Co A Ketone bodies β-hydroxybutyric acid Acetoacetic acid Acetone Citric acid cycle 16 C fatty acid = 108 ATP!!!!!! Key 1 Glycerol = 1 pyruvic acid – ATP? Lipogenesis Lipolysis 26-13 5-37 Lipogenesis and Lipolysis Pathways Brown Fat Glucose Glucose 6-phosphate Is major site for thermogenesis Brown fat produces an uncoupling protein - causing H+ to leak out of inner mitochondrial membrane Less ATP is produced, causing electron transport system to be more active Heat produced instead of ATP!!!!!!!!!!!!!! Glycerol PGAL (phosphoglyceraldehyde) Stored triglycerides Fatty acids Glycerol Beta oxidation Pyruvic acid Fatty acids Acetyl groups New triglycerides Acetyl-Co A Citric acid cycle Ketone bodies β-hydroxybutyric acid Acetoacetic acid Acetone Key Lipogenesis Lipolysis 1 Glycerol = 1 pyruvic acid – ATP? 26-16 5-38 Lipogenesis and Lipolysis Pathways Ketone Bodies are continually broken down and resynthesized Ensures blood contains fatty acids for aerobic respiration If lipolysis exceeds fatty acid use - i.e., fasting (& diabetes) (i.e., lots of fat is broken down very quick) - blood conc. of fatty acids increases - acetyl CoA derived from fatty acids makes ketone bodies - 2 acetyl CoA combined to form a 4 C molecule - acetoacetic acid/B-hydrobutyric acid/acetoacetic acid (3 C) Can be used for E under normal condition High levels cause acidic blood (acidosis) Gives breath an acetone smell 5-39 Glucose Triglycerides Glucose 6-phosphate Glycerol Stored triglycerides PGAL Fatty acids Glycerol Beta oxidation Pyruvic acid Fatty acids Acetyl groups New triglycerides Acetyl-Co A Ketone bodies β-hydroxybutyric acid Acetoacetic acid Acetone Citric acid cycle Key Lipogenesis Lipolysis 26-18 3 2/13/2012 Acetyl CoA - Review Break down of large Molecules to simple molecules Break down simple molecules to Acetyl CoA Oxidation of Acyetl CoA to H20 and CO2 – produce Eand make ATP 5-34 Proteins - Peptides Amino Acid Metabolism Nitrogen (N) is ingested primarily as protein (i.e., amino groups on the amino acids) Excess is excreted mainly as urea Short chains of amino acids Amino acids are linked by peptide bonds Formed by dehydration synthesis reactions (condensation) 2-45 Nitrogen (N) Balance Nitrogen balance = N ingested minus N excreted N balance: more N ingested than excreted Negative N balance: less N ingested than excreted In healthy adults amount of N excreted = amount ingested Excess amino acids can be converted into carbos and fat Positive 5-41 5-47 4 2/13/2012 Essential and Non-essential Amino Acids 20 Making amino acids (so we can make proteins!) amino acids are used to build proteins New amino acids can be obtained by transamination group transferred from one A.A. to another molecule to form a different A.A. Catalyzed by transaminase Amine 5-42 5-43 Oxidative Deamination – in liver! Transamination If more A.A. are present than needed to make protein excess amino acids are eliminated -NH2 is removed from glutamic acid, forming keto acid (and ammonia Ammonia is converted to urea and excreted Keto acid goes to Krebs or to fat or glucose A keto acid A keto acid (Keto Acid) Keto acid can be converted to Pyruvic Acid, AcetylCoA, or ketone acid 5-44 Gluconeogenesis (A.A.) Glutamic acid can also be made in liver from ammonia generated by intestinal bacteria 5-45 Gluconeogenesis Occurs when amino acids or other non-carbos are converted to Keto acids, then pyruvate, then glucose i.e., making glucose from non-carbohydrates Pyruvic They acid and acids of Krebs Cycle are keto acids possess a Keto group C=O 5-46 5-47 5 2/13/2012 Pathways of Amino Acid Metabolism Break down of large Molecules to simple molecules Glucose Pyruvic acid Protein Amino acids Keto acids Acetyl-CoA Break down simple molecules to Acetyl CoA Citric acid cycle –NH2 -ketoglutaric acid NH3 Urea cycle CO2 Glutamic acid Urea Oxidation of Acyetl CoA to H20 and CO2 – produce Eand make ATP Urine 26-31 Uses of Different Energy Sources Different cells Brain uses have different preferred energy substrates glucose as its major source of energy 5-48 6
