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ch 25 metabolism
metabolism
| Question | Answer |
|---|---|
| refers to all chemical reactions of the body and is of two types | Metabolism |
| two types of metabolic reactions | Catabolism and Anabolism |
| term for reactions that BREAK DOWN complex organic compounds into simpler ones | Catabolism |
| term for reactions that COMBINE simple molecules into more complex ones | Anabolism |
| ___ reactions are exergonic - they PRODUCE more than they consume | Catabolic |
| ___ reactions are endergonic - they CONSUME more energy than they produce | Anabolic |
| examples of catabolism | Glycolysis, Kreb's Cycle, Electron Transport Chain |
| examples of anabolism | Protein Synthesis (peptide bond formation), Building Fatty Acids into phospholipid bilayer (cell membrane), Glycogen Synthesis from glucose |
| coupling of catabolism and anabolism occurs via ___ and is the most frequently used | ATP - "energy currency" molecule of the cell |
| ___ reactions PRODUCE ATP (ADP + P + energy) | Catabolic |
| ___ reactions SPEND ATP | Anabolic |
| two important components of energy transfer | oxidation-reduction reactions, and ATP generation |
| the removal of electrons from an atom; the result is a Decrease in the potential energy of the atom or molecule | Oxidation |
| oxidation-reduction reactions usually involves loss of ___ atoms in biological systems, therefore called DEHYDROGENATION reactions | Hydrogen |
| in animal cells, electrons and hydrogen are usually transferred to ___ & ___ (the 2 coenzymes commonly used by animal cells to carry hydrogen atoms) | NAD & FAD |
| the 2 coenzymes, NAD & FAD, ultimately transfer hydrogen to ___ ___ ___ in mitochondria | electron transport chain |
| is usually an exergonic reaction (energy-releasing) | oxidation |
| energy released during ___ reactions is captured within a cell when ATP is formed | oxidation |
| (ADP + P = ATP) Addition of phosphate group to a molecule is termed ___, and increases its potential energy | phosphorylation |
| ATP generation, in animals, occurs by: | substrate-level phosphorylation and oxidative phosphorylation |
| generates ATP by direct transfer of a high-energy phosphate group (from a substrate) directly to ADP | substrate-level phosphorylation |
| substrate-level phosphorylation occurs in the ___ of cell | cytosol |
| REMOVES electrons and passes them through the electron transport chain (electron acceptors) to molecules of O2 | oxidative phosphorylation |
| oxidative phosphorylation occurs in the ___ ___ membrane of cells | inner mitochondrial |
| during digestion of carbs, polysaccharides & disaccharides are hydrolyzed into the monosaccharides ___, ___, & ___ | glucose (about 80%), fructose, & galactose |
| ___ converts most fructose and galactose into glucose | hepatocytes (liver cells) |
| fate of glucose | 1. ATP production 2. Amino acid synthesis 3. Glycogen synthesis 4. Triglyceride synthesis (lipogenesis) |
| the body's preferred source for synthesis of ATP | glucose |
| storage form of glucose in liver & muscle cells | glycogen |
| when glycogen storage areas are filled up, liver and muscle cells converts glucose to ___ & ___ that can be used for lipogenesis (tri synthesis) | glycerol & fatty acids |
| triglycerides are deposited into ___ ___, which has unlimited storgage capacity | adipose tissue |
| how does glucose enter cells? | by SECONDARY ACTIVE TRANSPORT, by facilitated diffusion at GluT4 transporters in most BODY CELLS, and by facilitated diffusion at GluT transporters in LIVER CELLS & NEURONS |
| Glucose absorption in GIT & kidney tubules accomplished via this | secondary active transport (Na+/glucose symporters) |
| a high level of insulin increases the insertion of ___ into plasma membranes of most body cells, thereby increasing rate of facilitated diffusion of glucose into cells | GluT4 |
| ___ transporters DO NOT INCREASE in number in response to insulin in hepatocytes and neurons | GluT |
| the complete oxidation of glucose to CO2 and H20 to produce ATP | cellular respiration |
| cellular respiration involves four sets of reactions | 1. glycolysis 2. formation of acetyl CoA 3. Kreb's cycle 4. electron transport chain |
| is the breakdown of glucose into 2 molecules of pyruvic acid; results in net gain of 2 molecules of ATP | Glycolysis |
| glycolysis requires a series of ___ reactions; doesn't require O2 (anaerobic cellular respiration) | 10 |
| glycolysis occurs in the ___ when phosphofructokinase activity is high | cytosol |
| key regulator of the rate of glycolysis | phosphofructokinase |
| glycolysis levels are high when levels of __ are high; when it's low, most glucose is converted to ___ | ADP; glycogen |
| fate of pyruvic acid depends on availability of ___ | O2 |
| when oxygen is in short supply, pyruvic acid is reduced to __ acid | lactic |
| when oxygen is high, ___ is produced; this reaction occurs inside the ___ ___ | acetyl coA; mitochondrial matrix |
| under ___ conditions, pyruvic acid enters the mitochondria, converted into ___, and enters the ___ | aerobic; acetyl coA; Kreb's cycle |
| fate of acetyl coA | enters Kreb's cycle in matrix (middle)of mitochondria |
| consists of a series of 8 oxidation-reduction reactions & decarboxylation reaction that release CO2 | Kreb's cycle |
| in the Kreb's cycle, the oxidation-reduction reactions transfer chemical energy, in the form of electrons, to 2 coenzymes - | NAD+ and FAD |
| 3 main results of the Krebs cycle | 1. ATP production 2. formation/release of CO2 3. production of reduced coenzymes for energy storage |
| for each molecule of pyruvic acid that is converted to acetyl coA and then enters the Krebs cycle produces __ molecules of CO2, __ molecules of NADH and H+, __ molecule of FADH2, and __ molecule of ATP | 3; 4; 1; 1 |
| the reduced conenzymes ___ and ___ are the most important outcomes of the Krebs cycle because the contain the energy originally stored in glucose and then in pyruvic acid | NADH and FADH2 |
| fate of NADH and H+ | passes along the electron transport chain |
| the electron transport chain is: | a series of electron carriers in inner mitochondrial membrane; a series of oxidation-reduction rx where energy in NADH and FADH2 is liberated and transferred to ATP |
| electron transport chain pumps __ to space between inner and outer membrane | H+ |
| in ___, ATP is produced when H+ flows/diffuses back inside mitochondrial matrix; it links chemical reactions with the pumping of H+ ions | chemiosmosis |
| electron transport chain uses several types of molecules including __, __, __ as electron carriers | cytochromes, CoQ, and FMN |
| electron transport chain ultimately transfers __ to __ atoms | electrons to oxygen |
| cellular respiration of 1 molecule of glucose produces ___ ATPs and ___ CO2; and uses __ O2 | 36 or 38; 6; 6 |
| other fates of glucose | used for synthesis of glycogen, and produced by breakdown of proteins and lipids |
| except for glycolysis, which occurs in the ___, all other reactions of cellular respiration occur within the ___ | cytosol, mitochondria |
| synthesis of glycogen; conversion of Glucose to Glycogen for storage in the liver and skeletal muscle | glycogenesis |
| glycogenesis stimulated by | insulin |
| conversion/breakdown of glycogen to glucose; occurs between meals | glycogenolysis |
| glycogenolysis stimulated by | glucagon and epinephrine |
| the 10 reactions that convert glucose to pyruvic acid | glycolysis |
| when body requires ATP, glycogen stored in hepatocytes is broken down into glucose and released into blood | glycogenolysis |
| conversion of noncarbohydrate molecules into glucose; making new glucose from proteins and fats | glyconeogenesis |
| gluconeogenesis occurs when liver is low on __ | glycogen |
| the glycerol portion of ___, ___ acid, & certain ___ acids are converted in the liver to glucose | triglycerides, lactic, amino |
| most lipids, such as triglycerides, are nonpolar and do not dissolve in ___ | water |
| for lipids to be transported in watery blood they must be made more water-soluble by combining with __ produced in liver and intestine | proteins |
| the lipid and protein combination formed are called __ | lipoproteins |
| lipoproteins are spherical particles with an outer shell of __, __, & __ molecules surrounding an inner core of __ & other lipids | proteins, phospholipids, cholesterol, triglycerides |
| 4 lipoprotein categories and named according to density; those containing more protein are more dense | 1. Chylomicrons 2. VLDL 3. LDL 4. HDL |
| transport ingested lipids to adipose tissue for storage | Chylomicrons |
| transport triglycerides synthesized in hepatocytes to adipocytes for storage | VLDLs |
| deliver cholesterol to cells throughout body for use in repair of cell membrane & synthesis of steroid hormones and bile salts | LDLs |
| deposit cholesterol in smooth muscle of arteries forming fatty plaques; aka BAD cholesterol | LDLs |
| remove excess cholesterol from body cells and take it to liver for elimination; aka GOOD cholesterol | HDLs |
| transport lipids in the bloodstream | lipoproteins |
| most cholesterol made by the ___, but it is also present in some foods | liver |
| cholesterol necessary for | cell membranes |
| cholesterol also necessary for synthesis of | steroid hormones and bile |
| as total cholesterol levels __, the risk of coronary artery disease __ | increase, increases |
| fate of lipids: may be __ to produce __ | oxidized, ATP |
| fate of lipids: stored in ___ tissue and in liver | adipose |
| fate of lipids: used to synthesize other substances like ___ & ___ | phopholipids, lipoproteins |
| 2 essential fatty acids that the body cannot synthesize are ___ acid and ___ acid; they must be provided in ___ | linoleic, linolenic, foods |
| triglycerides stored in ___ tissue constitutes ___% of all body energy reserves | adipose, 98% |
| the splitting/breakdown of triglycerides into glycerol and fatty acids | lipolysis |
| lipolysis stimulated by | E, NE, & cortisol |
| lipolysis occurs in | adipose cells & hepatocytes |
| lipolysis generates more ATP than | glycolysis |
| fate of glycerol and fatty acids: glycerol may be used to produce ___ or converted to acetyl CoA for use in the __ __ | glucose, Krebs cycle |
| fate of glycerol and fatty acids: fatty acids may undergo ___ oxidation to produce acetyl CoA which may be used by liver cells to produce ___ bodies | beta, ketone |
| fate of glycerol and fatty acids: fatty acids, alternatively, may undergo beta oxidation and enter Kreb's cycle as ___ ___ | acetyl CoA |
| the synthesis of lipids from glucose or amino acids; making of fat | lipogenesis |
| lipogenesis occurs in | liver and adipose cells |
| lipogenesis stimulated by | insulin |
| during digestion, ___ are broken down into amino acids | proteins |
| unlike ___ and triglycerides (lipids), which are stored, proteins are not stored | carbohydrates |
| instead amino acids (produced from protein catabolism) are either ___ to produce ATP or used to synthesize new ___ | oxidized, proteins |
| excess amino acids are not excreted in urine or feces but instead are converted into ___ or ___ | glucose (gluconeogenesis) or triglycerides (lipogenesis) |
| fate of proteins: biological catalysts (they function as ___) | enzymes |
| fate of proteins: transportators of membrane proteins, ___ and ___ | globulins and hemoglobin |
| fate of proteins: defense against disease (serve as ___ & ___) | antibodies and complement |
| fate of proteins: structural support | collagen, elastin & keratin |
| a certain amount of protein catabolism (breakdown) occurs each day and is stimulated by | cortisol |
| proteins from worn-out cells (such as RBCs) are broken down into ___ and recycled | amino acids |
| ___ convert amino acids to fatty acids, ketone bodies or glucose | hepatocytes |
| in order for body cells to ___ amino acids to produce ATP, they must be ___ by liver cells | oxidize, deaminated |
| before amino acids can enter the Krebs cycle their amino group must first be removed, this process is called | deamination |
| deamination produces ___ which is converted to urea (less toxic) and excreted in urine | ammonia |
| the formation of peptide bonds between amino acids to produce new proteins | protein anabolism |
| protein anabolism occurs on the ___ of almost every cell in the body | ribosomes |
| the 3 molecules that play a key role in metabolism | glucose 6-phospate, pyruvic acid, and acetyl CoA |
| glucose 6-phosphate produced from ___ after it enters cells | glucose |
| fates of these 3 molecules depend on ___ or ___ status of individual (how long it's been since we ate) | nutritional or activity |
| metabolism depends on how much ___ has passed since the last meal | time |
| during the ___ ___, ingested nutrients are entering bloodstream, and glucose is readily available for ATP production | absorptive state |
| during the ___ ___, absorption of nutrients from the GIT is complete, and energy needs must be met by fuels already in the body | postabsorptive state |
| most meals require ___ hours for absorption | 4 |
| given 3 meals per day, absorptive state last ___ hours | 12 |
| the effects of __ dominate in the absorptive state | insulin |
| the effects of ___, ___, ___ dominate in the postabsorptive state | glucagon, E, and NE |
| insulin effects in absorptive state: stimulates ___ and decreases ___ | anabolism, catabolism |
| insulin effects in absorptive state: promotes entry of ___ and ___ into cells of many tissues | glucose, amino acids |
| insulin effects in absorptive state: stimulates conversion of ___ to ___ in liver and muscle cells | glucose to glycogen |
| insulin effects in absorptive state: stimulates synthesis of ___ in liver and adipose tissue | triglycerides |
| insulin effects in absorptive state: stimulates ___ synthesis in cells throughout body | protein |
| during postabsorptive state, maintaining a steady level of ___ ___ is critical because the nervous system and RBCs can only safely use glucose for energy | blood glucose |
| fatty acids can not pass __ barrier; RBCs have no ___ | blood/brain; mitochondria |
| glycogenolysis and ___ provide most energy needs (in postabsorptive state) | lipolysis |
| complete oxidation of glucose to produce ATP | cellular respiration |
| cellular respiration consists of: | glycolyis, krebs cycle, and electron transport chain |
| complete oxidation of 1 molecule of glucose yields a maximum of 36 or 38 molecules of ATP. True or False? | True |
| the conversion of glucose into pyruvic acid; anaerobic cellular respiration | glycolysis |
| cycle includes a series of oxidation-reduction reactions in which coenzymes (NAD+ and FAD) pick up H+; aerobic | krebs cycle |
| third set of reactions in glucose catabolism in which electrons are passed from one carrier to the next, and most of the ATP is produced; aerobic | electron transport chain |
| glucose converted into glycogen for storage | glycogenesis |
| glycogen converted into glucose | glycogenolysis |
| conversion of amino acids, glycerol, and lactic acid into glucose | gluconeogenesis |
| during fasting and starvation, ___ and ___ are increasingly utilized for ATP production | fatty acids and ketone bodies |
| ketone body production increases as catabolism of __ rises | fatty acids |
| by the second day of a fast, the level of __ has risen fourfold due to ___ | fatty acids, lipolysis |
| heat loss must equal rate of heat __ (by metabolism) | production |
| heat is measured as __ and expressed in units called ___ | temperature, calories |
| a ___ is the amount of heat/energy required to raise the temp of 1 gm of water 1 degree centigrade | calorie |
| a __ or ___ = 1000calories (used to measure the body's Metabolic Rate and to express the energy content of foods) | kilocalorie or Calorie |
| normal core (internal) temperature is maintained by balance between heat-producing and heat-losing mechanisms | True |
| a core temp that is too __ causes cardiac arrythmias | low |
| a core temp that is too __ kills by denaturing cody proteins | high |
| factors that affect metabolic rate and rate of heat production: | 1. exercise 2. thyroid hormone 3. stress 4. fever 5. ingestion of food 6. youth |
| heat exchange that occurs between substances/molecules in direct contact with each other | conduction |
| transfer of heat by the movement of a fluid (gas or liquid) between areas of different temps [transfer of heat to air or water in contact with the body] | convection |
| transfer of heat from a warmer object to a cooler object in the form of infrared rays without physical contact | radiation |
| conversion of liquid to a vapor; heat lost in this process | evaporation |
| control center that functions as the body's thermostat | hypothalamus |
| 2 parts of hypothalamus that raise and lower body temp | heat-losing center (decreases body temp) and heat-promoting center (increase body temp) |
| responses that produce, conserve, or retain heat when core temp falls are: | vasoconstriction in skin (slows heat loss); release of E & NE (which increases cellular metabolism); and Shivering (which increases heat production) |
| when energy content of food equals energy used by cells of body, weight ___ ___ | remains constant |
| energy intake depends on ___ of food consumed; affluent nations have more obese people | amount |
| factors that affect food intake | stress, neural and endocrine signals |
| control center in brain for food intake | hypothalamus |
| body uses nutrients for __ maintenance and ___ | growth and repair |
| six main types of nutrients | water, carbs, lipids, proteins, vitamins & minerals |
| guidelines for healthy eating: | use sugars, salt, sodium and alcohol in moderation; eat a variety of foods; get plenty of fruit, veg, & grains; maintain healthy weight; and choose foods low in fat, saturated fat, and cholesterol |
| Major role of ___ is to regulate enzymatic reactions ie. Ca, Fe, Mg, Manganese | minerals |
| most abundant minerals in body and forms part of bone matrix | calcium and phosphorous |
| minerals also work in ___ systems to control pH (Na+, P), and to regulate ___ of water (Na+); and are involved in generation of ___ impulses | buffer, osmosis, nerve |
| are inorganic | minerals |
| are organic | vitamins |
| most serve as coenzymes, and only required in small amounts | vitamins |
| 3 vitamins that are antioxidants ___ inactivate oxygen-free radicals | C, E, and beta carotene |
| 2 major groups of vitamins | fat-soluble and water-soluble |
| absorbed with fats/lipids and include A, D, E, and K | fat-soluble vitamins |
| are dissolved in body fluids (with excess eliminated thru urine) and include several B vitamins and vitamin C | water-soluble |
| the thermostat and food intake regulating center of the body is in the ___ of the brain | hypothalamus |
| the three key molecules of metabolism are ___, ___, and ___. | glucose 6 phosphate, pyruvic acid, acetyl CoA |
| Vitamins A, B, D and K are fat-soluble vitamins. True or False? | False |
| NAD+ and FAD are: | 1. both derivatives of B vitamins 2. are used to carry H+ released during oxidation rx 3. become NADH & FADH2 in their reduced forms 4. act as coenzymes in the Krebs cycle 5. are the final electron acceptors in the electron transport chain (FALSE) |
| During Glycolysis: | 1. a 6-carbon glucose is split into 2 3-carbon pyruvic acids 2. there is a net gain of 2 ATP molecules 3. 2 NADH molecules are oxidized (FALSE) 4. moderatly high levels of O2 are needed (FALSE) 5. activity of PFK determines rate of the chemical rx |
| If glucose is not needed for immediate ATP production, it can be used for : | 1. vitamin synthesis (FALSE) 2. amino acid synthesis 3. gluconeogenesis (FALSE) 4. glycogenesis 5. lipogenesis |
| the correct sequence for the oxidation of glucose (aka cellular respiration) to produce ATP is: | glycolysis, formation of acetyl CoA, Krebs cycle, electron transport chain |
| you would NOT experience the following during fasting or starvation: | 1. DECREASE in plasma fatty acid levels (CORRECT ANSWER) 2. + in ketone body formation 3. lipolysis 4. + use of ketones for ATP production in the brain 5. depletion of glycogen |
| if the core temp rises above normal, the following would occur to cool the body: | 1. dilation of vessels in skin 2. + radiation & conduction of heat to environment 3. + metabolic rate (FALSE) 4. evaporation of perspiration 5. + secretion of Thyroid hormones (FALSE) |
| the following situations would increase the metabolic rate: | 1. after ingesting foods 2. + secretion of thyroid hormones 3. sleep (no, this lowers MR) 4. parasympathetic nervous system stimulation (no, sympathetic) 5. fever |
| which of the following are absorptive state reactions? | 1. aerobic cellular respiration 2. glycogenesis 3. glycogenolysis (False) 4. gluconeogenesis using lactic acid (False) 5. lipolysis (False) |
| hormones and the reaction they regulate: | |
| phosphofructokinase | glycolysis |
| insulin | glycogenesis |
| glucagon and Epinephrine | glcyogenolysis |
| cortisol and glucagon | gluconeogenesis |
| E, NE, and cortisol, and thyroid hormones | lipolysis |
| insulin | lipogenesis |
| cortisol | catabolism of proteins |
| insulin | absorptive state |
| glucagon, E and NE | postabsorptive state |
| foods that we eat are used to supply energy forlife processes, serve as building blocks for synthesis rx, or are stored for future use. | TRUE |
| DELIVER CHOLESTEROL TO BODY CELLS for use in repair of membranes and synthesis of steroid hormones and bile salts | LDL |
| REMOVE EXCESS CHOLESTEROL FROM BODY CELLS and transport it to the liver for elimination | HDL |
| TRANSPORT endogenous lipids to ADIPOCYTES FOR STORAGE | VLDL |
| CARRIERS of electrons in the electron transport chain | Cytochromes |
| ORGANIC nutrients required in small amounts for growth and normal metabolism | Vitamins |
| INORGANIC substances that perform many vital functions | Minerals |
| the body's preferred source for synthesizing ATP | Glucose |
| nutrient molecules that can be oxidized to produce ATP or STORED in adipose tissue | Lipids |
| composed of Amino Acids and are the primary regulatory molecules in the body | Proteins |
| energy-transferring molecule of the body | ATP |
| hormone secreted by adipocytes that acts to decrease total body-fat mass | leptin |
| neurotransmitter that stimulates food intake | neuropeptide Y |
| acetoacidic acid, hydroxybutyric acid, and acetone | Ketone bodies |
| refers to all chemical reactions in the body | metabolism |
| EXERGONIC chemical reaction that BREAKS DOWN complex organic molecules into simpler ones | Catabolism |
| ENDERGONIC chemical reaction that COMBINES SIMPLE molecules to make more complex ones | Anabolism |
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