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Key Terms Chapter 24: Metabolism and Nutrition

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    62676
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    absorptive state
    also called the fed state; the metabolic state occurring during the first few hours after ingesting food in which the body is digesting food and absorbing the nutrients
    acetyl coenzyme A (acetyl CoA)
    starting molecule of the Krebs cycle
    anabolic hormones
    hormones that stimulate the synthesis of new, larger molecules
    anabolic reactions
    reactions that build smaller molecules into larger molecules
    ATP synthase
    protein pore complex that creates ATP
    basal metabolic rate (BMR)
    amount of energy expended by the body at rest
    beta (β)-hydroxybutyrate
    primary ketone body produced in the body
    beta (β)-oxidation
    fatty acid oxidation
    bile salts
    salts that are released from the liver in response to lipid ingestion and surround the insoluble triglycerides to aid in their conversion to monoglycerides and free fatty acids
    biosynthesis reactions
    reactions that create new molecules, also called anabolic reactions
    body mass index (BMI)
    relative amount of body weight compared to the overall height; a BMI ranging from 18–24.9 is considered normal weight, 25–29.9 is considered overweight, and greater than 30 is considered obese
    calorie
    amount of heat it takes to raise 1 kg (1000 g) of water by 1 °C
    catabolic hormones
    hormones that stimulate the breakdown of larger molecules
    catabolic reactions
    reactions that break down larger molecules into their constituent parts
    cellular respiration
    production of ATP from glucose oxidation via glycolysis, the Krebs cycle, and oxidative phosphorylation
    cholecystokinin (CCK)
    hormone that stimulates the release of pancreatic lipase and the contraction of the gallbladder to release bile salts
    chylomicrons
    vesicles containing cholesterol and triglycerides that transport lipids out of the intestinal cells and into the lymphatic and circulatory systems
    chymotrypsin
    pancreatic enzyme that digests protein
    chymotrypsinogen
    proenzyme that is activated by trypsin into chymotrypsin
    citric acid cycle
    also called the Krebs cycle or the tricarboxylic acid cycle; converts pyruvate into CO2 and high-energy FADH2, NADH, and ATP molecules
    conduction
    transfer of heat through physical contact
    convection
    transfer of heat between the skin and air or water
    elastase
    pancreatic enzyme that digests protein
    electron transport chain (ETC)
    ATP production pathway in which electrons are passed through a series of oxidation-reduction reactions that forms water and produces a proton gradient
    energy-consuming phase
    first phase of glycolysis, in which two molecules of ATP are necessary to start the reaction
    energy-yielding phase
    second phase of glycolysis, during which energy is produced
    enterokinase
    enzyme located in the wall of the small intestine that activates trypsin
    evaporation
    transfer of heat that occurs when water changes from a liquid to a gas
    FADH2
    high-energy molecule needed for glycolysis
    fatty acid oxidation
    breakdown of fatty acids into smaller chain fatty acids and acetyl CoA
    flavin adenine dinucleotide (FAD)
    coenzyme used to produce FADH2
    glucokinase
    cellular enzyme, found in the liver, which converts glucose into glucose-6-phosphate upon uptake into the cell
    gluconeogenesis
    process of glucose synthesis from pyruvate or other molecules
    glucose-6-phosphate
    phosphorylated glucose produced in the first step of glycolysis
    glycogen
    form that glucose assumes when it is stored
    glycolysis
    series of metabolic reactions that breaks down glucose into pyruvate and produces ATP
    hexokinase
    cellular enzyme, found in most tissues, that converts glucose into glucose-6-phosphate upon uptake into the cell
    hydroxymethylglutaryl CoA (HMG CoA)
    molecule created in the first step of the creation of ketone bodies from acetyl CoA
    inactive proenzymes
    forms in which proteases are stored and released to prevent the inappropriate digestion of the native proteins of the stomach, pancreas, and small intestine
    insulin
    hormone secreted by the pancreas that stimulates the uptake of glucose into the cells
    ketone bodies
    alternative source of energy when glucose is limited, created when too much acetyl CoA is created during fatty acid oxidation
    Krebs cycle
    also called the citric acid cycle or the tricarboxylic acid cycle, converts pyruvate into CO2 and high-energy FADH2, NADH, and ATP molecules
    lipogenesis
    synthesis of lipids that occurs in the liver or adipose tissues
    lipolysis
    breakdown of triglycerides into glycerol and fatty acids
    metabolic rate
    amount of energy consumed minus the amount of energy expended by the body
    metabolism
    sum of all catabolic and anabolic reactions that take place in the body
    minerals
    inorganic compounds required by the body to ensure proper function of the body
    monoglyceride molecules
    lipid consisting of a single fatty acid chain attached to a glycerol backbone
    monosaccharide
    smallest, monomeric sugar molecule
    NADH
    high-energy molecule needed for glycolysis
    nicotinamide adenine dinucleotide (NAD)
    coenzyme used to produce NADH
    oxidation
    loss of an electron
    oxidation-reduction reaction
    (also, redox reaction) pair of reactions in which an electron is passed from one molecule to another, oxidizing one and reducing the other
    oxidative phosphorylation
    process that converts high-energy NADH and FADHinto ATP
    pancreatic lipases
    enzymes released from the pancreas that digest lipids in the diet
    pepsin
    enzyme that begins to break down proteins in the stomach
    polysaccharides
    complex carbohydrates made up of many monosaccharides
    postabsorptive state
    also called the fasting state; the metabolic state occurring after digestion when food is no longer the body’s source of energy and it must rely on stored glycogen
    proteolysis
    process of breaking proteins into smaller peptides
    pyruvate
    three-carbon end product of glycolysis and starting material that is converted into acetyl CoA that enters the Krebs cycle
    radiation
    transfer of heat via infrared waves
    reduction
    gaining of an electron
    salivary amylase
    digestive enzyme that is found in the saliva and begins the digestion of carbohydrates in the mouth
    secretin
    hormone released in the small intestine to aid in digestion
    sodium bicarbonate
    anion released into the small intestine to neutralize the pH of the food from the stomach
    terminal electron acceptor
    oxygen, the recipient of the free hydrogen at the end of the electron transport chain
    thermoneutral
    external temperature at which the body does not expend any energy for thermoregulation, about 84 °F
    thermoregulation
    process of regulating the temperature of the body
    transamination
    transfer of an amine group from one molecule to another as a way to turn nitrogen waste into ammonia so that it can enter the urea cycle
    tricarboxylic acid cycle (TCA)
    also called the Krebs cycle or the citric acid cycle; converts pyruvate into CO2 and high-energy FADH2, NADH, and ATP molecules
    triglycerides
    lipids, or fats, consisting of three fatty acid chains attached to a glycerol backbone
    trypsin
    pancreatic enzyme that activates chymotrypsin and digests protein
    trypsinogen
    proenzyme form of trypsin
    urea cycle
    process that converts potentially toxic nitrogen waste into urea that can be eliminated through the kidneys
    vitamins
    organic compounds required by the body to perform biochemical reactions like metabolism and bone, cell, and tissue growth
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