問題一覧
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• Transforming small molecules into big molecules constituting the body structures and machinery. • It is energy requiring, e.g., glycogenesis and lactose synthesis
ANABOLIC PATHWAYS
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• Breakdown of large molecules into smaller molecules to produce energy or smaller molecules or reducing equivalents
CATABOLIC PATHWAYS
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• They are utilized for both anabolic and catabolic purposes • e.g., glycolysis and Krebs' cycle.
AMPHIBOLIC PATHWAYS
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Biochemical process by which food molecules are broken down into simpler chemical units that can be used by cells for their metabolic needs
DIGESTION
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starch, glycogen, maltose, sucrose, and lactose (oligosaccharides and polysaccharides).
Digestible carbohydrates
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• Which do not need digestion and are absorbed • e.g., monosaccharides: glucose, mannose, galactose, fructose and pentoses.
Ready-to-absorb carbohydrate
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• Which are called dietary fibers. • These include cellulose, gums and pectins. • They are very important for stools excretion and are anticancer and intestinal bacteria feed on it to release certain vitamins.
Non-digestible carbohydrates
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• salivary amylase (PTYALIN) is produced by the salivary glands. • Its optimum pH is 6.7 - 6.8 and is activated by chloride ions • specific for hydrolysis of -1,4 glucosidic linkage present in cooked starch and glycogen from meat to produce smaller disaccharides and maltose • Salivary amylase cannot digest -1,4 glucosidic linkage in cellulose.
MOUTH
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CARBOHYDRATE DIGESTION IN _____ Salivary amylase continues to act on starch, glycogen or dextrins for 2-3 minutes only in the stomach
BUCCAL CAVITY
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CARBOHYDRATE DIGESTION IN _____ • Saliva is 99% water and small amounts of inorganic and organic molecules • Triggered by taste, smell, sight and thought of food • 1.5L saliva/day
STOMACH
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CARBOHYDRATE DIGESTION IN _____ • In the _____, there are two juices that digest carbohydrates: • The pancreatic juice: • pancreatic amylase • an -glycosidase • has an optimum pH 7.1 • also activated by chloride ion • It acts exactly as salivary amylase • digesting cooked and uncooked starch • glycogen and starch dextrins which escaped digestion by salivary amylase in the mouth
SMALL INTESTINE
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___ SALIVA PER DAY
1.5L
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SALIVA IS ___% WATER
99
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two juices that digest carbohydrates
PANCREATIC JUICE AND PANCREATIC AMYLASE
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The final digestion of carbohydrates occurs in the small intestine by the action of the following disaccharidases: ______, ______, _____ .
SUCRASE, MALTASE, LACTASE
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_____ hydrolyzes lactose into glucose and galactose.
LACTASE
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3 major breakdown products
GLUCOSE, FRUCTOSE, GALACTOSE
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GLUCOSE, FRUCTOSE, GALACTOSE These monosaccharides are absorbed through the ______
INTESTINAL WALL
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In the bloodstream, they are transported to the _____
LIVER
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_____ and ______ rapidly converted to compounds that are metabolized by the same pathway as glucose
FRUCTOSE, GALACTOSE
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Central focus of carbohydrates metabolism is a pathway called as
GLYCOLYSIS
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Glucose is converted into ______________
2 MOLECULES OF PYRUVATE
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Intracellular site and tissue distribution: • It occurs in the _____ of all tissues in the body
CELL CYTOSOL
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• are devoid of mitochondria and depend on glycolysis as the main source of energy. • Mammalian erythrocyte is unique in that about 90% of its total energy requirement is provided by glycolysis.
RBC
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due to occlusion of blood vessels by the muscular contraction that decreases oxygen
Contracting muscles
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which have a limited blood supply and lack mitochondria which if present would absorb and scatter light interfering with transparency.
Cornea, lens and some parts of retina
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where there are relatively few mitochondria.
Kidney (medulla), testicles, leukocytes and white muscle fibers
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due to dissociation of the high rate of glycolysis from Krebs', i.e., aerobic production of lactate.
Cancer Cells
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also normally derive most of their energy from glycolysis
Brain and gastrointestinal tract
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• Glucose oxidation producing ATP. • It is the major source of energy in certain tissues e.g.,RBCsandskeletalmuscles. • It provides pyruvic acid needed for Krebs' cycle. • It is a link with fat metabolism, e.g., dihydroxyacetone phosphate into glycerol 3- phosphate in adipose tissue. • It a link with amino acid metabolism, e.g., 3- phopshoglycerate into serine and pyruvate into alanine and vice versa. • Production of 2,3-DPG that is important in tissue oxygenation.
GLYCOLYSIS
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7. It is the major source of ______ that is gluconeogenic.
LACTIC ACID
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8. Reversal of _____ is ________, an important source of glucose
GLYCOLYSIS, GLUCONEOGENESIS
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Main pathway of metabolism of ____ from the diet.
FRUCTOSE
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A small number of genetic diseases occur due to deficiency in activity of enzymes of glycolysis, are manifested mainly as ______
HEMOLYTIC ANEMIAS
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_______ are glycolytic producing large amount of lactate, favoring a relatively acidic local pH in the tumor, a situation that was utilized to develop therapy for cancer that could be locally activated by this acidic pH.
CANCER CELLS
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• Stimulates synthesis of glucokinase, phosphofructokinase and pyruvate kinase, so it stimulates glycolysis. • It also induces glucose transporters to provide cells with glucose for glycolysis
INSULIN
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______ and ______ are inhibitory by inhibiting pyruvate kinase
ADRENALINE, GLUCAGON
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are those enzymes that catalyze the irreversible steps of glycolysis
Phosphofructokinase, Hexokinase, Pyruvate kinase
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• Pyruvate • Produced from glucose via glycolysis • End product of glycolysis
FATES OF PYRUVATE
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The metabolic pathway by which glycogen is synthesized from glucose 6-phosphate
GLYCOGENESIS
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• Metabolic pathway by which glucose 6- phosphate is produced from glycogen • In muscles and brain cells,an immediate need for energy is the stimulus that initiates ______ • Needs the enzyme glucose 6-phosphatase to convert G6P to glucose before it can enter the bloodstream
GLYCOGENOLYSIS
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Muscle and brain cells lacks ____
G6 PHOSPHATASE
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- Synthesis of glucose from noncarbohydrate materials • Pyruvate • Lactate (muscles and RBC) • Glycerol (triacylglycerol hydrolysis) • Amino acids ( muscle protein during starvation) - 90% in the liver - Helps maintain blood sugar level in times of inadequate dietary CHO intake
GLUCONEOGENESIS
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________ occurs during replenishing depleted liver, converting lactase back to glucose, maintain blood glucose levek when glucogen stores has beed depleted
GLUCONEOGENESIS
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LACTATE formed from glucose under anaerobic conditions in muscle cells is transferred to the liver, where it is reconverted to glucose which is then transferred back to the muscle cells
CORI CYCLE
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- Metabolic pathway by which G6P is used to produced NADPH and other sugar phosphates - Significant in cells that produce lipids • Fatty tissues • Liver • Mammary glands • Adrenal cortex
PENTOSE PHOSPHATE PATHWAY