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17 Cards in this Set
- Front
- Back
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What is metabolism? |
Refers to the total of all chemical reactions occurring in the body. |
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What does metabolism include? |
Catabolism: break down complex molecules. - is exergonic: produces more energy than they consume.
Anabolism: combine simple molecules into complex ones. - in endergonic: consumes more energy than they produce. |
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What is ATP? |
Adenosine triphosphate: the "energy currency". ADP + Pi + energy = ATP |
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Metabolism circle |
* Simple molecules such as glucose, amino acids, glycerol and fatty acids .... leads to * Anabolic reactions which transfer energy from ATP to complex molecules. ..... leads to * Complex molecules such as glycogen, proteins, and triglycerides (releases heat) .... leads to * Catabolic reactions transfer energy from complex molecules to ATP .... leading back to simple molecules (releases heat) |
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Metabolism features and redox reactions |
- Central feature of metabolism and in energy transfer: transfer of phosphoryl group. ADP + P- + energy = ATP. - Reaction mechanism to transfer free energy in biological systems: transfer of electron on oxidation reduction reactions. - Oxygen is the strongest electron accessories in biological systems, due to it's very high electronegativity, hence making it the strongest oxidizing agent. |
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Describe the redox reactions |
Oxidation: atom LOSES an electron. (O2= common electron acceptor). Decrease in potential energy, Dehydrogenation (removal of hydrogens), liberated hydrogen transferred by coenzymes (NAD and FAD), glucose is oxidized in cellular respiration Reduction: atom GAINS an electron. Increase in potential energy, oxygen is reduced in cellular respiration. - redox reactions always occur in pairs: one atom loses the electron, the other gains it and energy is transferred from one to another. * Leo says GER (Lose electron oxidize, gain electron reduce) |
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Overview of energy and metabolism |
- Food (carbohydrates, lipids, proteins, nucleic acids)= only source of energy for the biological work of cells. - all molecules (nutrient molecules included) have stored energy (potential) in the bonds between their atoms. - the energy that runs most biological systems on earth comes from solar energy. - plants trap solar energy via the metabolic reactions of photosynthesis by producing molecules (glucose). |
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What are 3 things energy uses are for? |
1. Immediate use by cells to conduct their normal metabolic processes (muscle contraction, secretions, active transport) 2. Synthesis of structural or functional molecules to repair and replace cells (mitosis and cytokinesis) 3. Storage (glycogen or fat) for later use as energy (nutrient reserves) |
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Other ATP expenses |
- locomotion - contraction - intracellular transport - cytokinesis - endocytosis - exocytosis |
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Carbohydrate metabolism |
- glycogenesis: glucose to glycogen - glycolysis: glucose to pyruvic acid - lipogenesis: glucose to triglycerides (TG) - glycogenolysis: glycogen to glucose - gluconeogenesis: lactic acid, amino acids, TG to glucose - transamination: pyruvic acid + NH3 to amino acid - fate of glucose depends on need of body cells: ATP production or synthesis of amino acids, glycogen or TG. - GluT transporters bring glucose into cell via facilitated diffusion. - insulin causes insertion of more of these transporters, increasing rate of entry into cells. - glucose trapped in cells after being phosphorylated. |
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Glucogenic vs ketogenic in glucose metabolism |
Glucogenic: amino acids that can be used to make glucose. Ketogenic: amino acids that are converted to acetyl CoA. |
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Protein metabolism. Describe protein synthesis, protein catabolism, protein anabolism |
Protein metabolism: production of a protein molecule using an RNA model through a ribosome (translation), protein will then be modified through RER and golgi before secretion/use. Use of amino acids from digestion to build new protein. PROTEIN CATABOLISM: proteins are digested in the gut into amino acids (hydrolysis of peptide bonds) which are then absorbed into blood and extracellular fluid. Excess proteins can serve as fuel like carbohydrates and fats. Nitrogen is removed producing carbon skeletons (oxidized) and ammonia (detoxified and excreted in urine), is highly toxic, but soluble, can be excreted by aquatic organisms as ammonia but terrestrial organisms must detoxify it first. PROTEIN ANABOLISM: Transamination= adding an amino group (NH2) to pyruvic acid to produce any of the nonessential amino acids. Deamination: removing an amino group from an amino acid to form an acetyl molecule. |
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Lipid metabolism |
Lipolysis: break down TG in glycerol and 3 fatty acids (FA), glycerol enter glycolysis, FA are oxidized. Beta oxidation: break down FA into 2 carbon compound (acetyl CoA, cellular respiration). - oxidation of one 18-C stearic acid will net: 146 ATP. - glycerol nets: 22 ATP, so 1 triglyceride nets: 460 ATP. - by comparison: oxidation of 3 glucose (18 Cs) nets: 108 ATP. Lipogenesis: formation of lipids from non-lipids (glucose)
Lipoproteins: surrounding triglycerides with apoproteins to make them more transportable in water (carrier): - very low density lipoproteins (VLDLs) - low density lipoproteins (LDLs) - high density lipoproteins (HDLs) As found in the liver. |
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Metabolic overview: the absorptive state |
* Nutrient source: nutrients absorbed at digestive tract, to... * Distributed in bloodstream: lipids, amino acids, glucose, to... * Destinations: - ADIPOSE TISSUE: use: storage as triglycerides Stimulated by: insulin - SKELETAL MUSCLE: use: ATP production Stimulated by: insulin - ALL TISSUES: use: protein synthesis Stimulated by: insulin, GH, androgens/estrogens. - ALL TISSUES (EXCEPT SKELETAL MUSCLE: use: ATP production Stimulated by: insulin - LIVER AND SKELETAL MUSCLE: use: storage as glycogen Stimulated by: insulin
*all are stimulated by insulin. |
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Metabolic overview: the postabsorptive state |
Nutrient source: Liver: lipid and amino acid breakdown. Stimulated by: glucocorticoids (1. Gluconeogenesis and 2. Glycogenolysis. Stimulated by: 1. Glucocorticoids and 2. Glucagon, epinephrine). Adipose tissue: triglyceride breakdown. Stimulated by: epinephrine, glucocorticoids. Skeletal muscle: protein breakdown by cathepsins. Stimulated by: glucocorticoids. Glycogen breakdown and glycolysis. Stimulated by: glucagon, epinephrine.
Distributed in bloodstream: - ketone bodies - glucose - lipids - amino acids - lactic acid
Destinations: All tissues: Use: ATP production Stimulated by: glucocorticoids Neural tissue: Use: ATP production All tissues (except neural): Use: ATP production Stimulated by: glucocorticoids Liver: Use: gluconeogenesis and ketone body production. Stimulated by: glucocorticoids Use: gluconeogenesis Stimulated by: glucocorticoids |
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When a person overeats, draws on stores (fasting), in the fast. |
A. When a person overeats: eating in excess of energy needs, body stores a small amount of glycogen and much larger quantities of fat. B. When a person draws on stores (fasting): nutrients from a meal are no longer available to provide energy (2-3 hrs after meal), body draws on its glycogen and fat stores for energy. C. If the fast continues beyond glycogen depletion: (24hrs of starvation), body begins to break down its protein (muscle and lean tissue) to amino acids to synthesize glucose needed for brain and nervous system energy. Liver converts fats to ketone bodies, serving as alternative energy source for the brain, thus slowing breakdown of body protein. |
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Metabolism summary |
ENERGY METABOLISM: - aerobic respiration: glycolysis to pyruvate decarboxylation to citric acid cycle to oxidative phosphorylation (electron transport chain + ATP synthase). - anaerobic respiration: electron acceptors are other than oxygen. - fermentation: glycolysis to substrate level phosphorylation (ABE, ethanol, lactic acid)
SPECIFIC PARTS: - protein metabolism: protein synthesis, catabolism. - carbohydrate metabolism (carbohydrate catabolism and anabolism): human= glycolysis, gluconeogenesis, glycogenolysis, glycogenesis, pentose phosphate pathway. Nonhuman= photosynthesis, chemosythesis. - lipid metabolism (lipolysis, lipogenesis): fatty acid metabolism, other: steroids, etc. - amino acid: amino acid synthesis, urea cycle. - nucleotide metabolism: purine metabolism. - other: metal metabolism (iron), ethanol metabolism. |
