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36 Cards in this Set
- Front
- Back
Enzymes
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-proteins
-increase rate of reaction -do not change nature of reaction -are not consumed |
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activation energy
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-initial input energy required to start reaction
-allows molecules to get close enough to react and form products |
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ways to overcome activation energy
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-large amounts of heat, enzymes to lower it (then small amounts of heat can push it forward)
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How enzymes work
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-substrates brought closer together so they can react
-each active site has a characteristic conformation or shape that is specific for a particular substrate -ability of enzymes to lower energy requirement is due to structure |
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enzyme activity dependent on
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temp, ph, salt conc
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effect of temp
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increase rate of reaction until a few degrees above body temp, then enzyme denatured
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effect of ph. Where enzymes found, ph
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ph optimum- peak activty within narrow range due to changes in enzyme shape
-reflects where enzyme is found in (pepsin 2-3 stomach, salivary amylase (6-7), trypsin (8-9) small intestine |
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effects of salt concentration
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-if concentration close to 0, charged amino acid side chaines will attract to another
-if concentration high, normal interaction of charged groups will be blocked -(both the enzyme will denature and form preticipate) -inorganic ions may interact with active site by distrupting the H binding to the surround ionic residues |
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coenzymes
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transports H atoms and small molecules between enzymes (derive from water-soluble vitamins)
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cofactors
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help form active site through a conformation change of the enzyme or help in enzyme substante binding (metal ions such as Ca2+,Mg2+,Mn2+,Cu2+,Zn2+
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motility
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ingestion, mastication, deglutination (swallowing), peristalsis, segmentation (churning/mixing)
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secretion
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exocrine- digestive enzymes, acid, mucus. endocrine: hormones to regulate digestion
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immune barrier
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simple columar epithelium with tight junctions which prevent swallowed pathogens from entering body
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Carbohydrates begins in the mouth___, starch digestion begins in the __ by (enzyme). Ends?
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mouth,mouth, salivary amylase, additional starch digestion continues in small intestine by pancreatic amylase
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protein digestion begins in the ___, list types of cells
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stomach. Goblet, cheif, parietal cells
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goblet cells
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secrete mucous, protects against autodigestion of epithelium
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cheif cells
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secretes pepsinogen (inactive enzyme), which is activated to pepsin by HCl and by pepsin itself by in postiive feedback mechanism
-Zymogen- inactivate enzyme precursor that requires biochem activation |
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parietal cells
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secrete HCl (activated pepsin, pH (1.5-3.5) denatures protein in food, and kills many bacterial
-intrinsic factor: glycoprotein required for absorption of vitamin B12 in small intestine |
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protein --> large polypeptides
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pepsin from stomach glands in presence of Hcl, to stomach, amino acids are absorbed by cotransport with sodium ions
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large polypeptides--> small polypeptides/small peptides
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from pancreatic enzymes (trypsin, chmotrypsin, carboxpeptidase), to small intestine
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small polypeptides/peptides--> amino acids (somedipeptides, tripeptides)
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brush border enzymes (aminopeptidase, carboxypeptidase, dipeptidase), to small intestine
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Path of absorption Amino acids
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1) amino acids are absorbed by cotransport with sodium ions 2) some dipeptides/tripeptides are absorbed via cotransport with H ions and hyddrolyzed to amino acids within cells 3) Amino acids leave the epithilial cells by facilitated diffusion, enter the capillary blood in the villi, and are trasnported to the liver via the hepatic portal vein
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Lipid digestion begins in the ____ and completed in the ____ by _____
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small intestine, small intestine, pancreatic lipase
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Small intestine Villi
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motile fingerlike entensions of mucosa, simple columnar epithelium and goblet cells
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small intestine microvilli
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-projections (brush border) of absorptive cells
-contains brush border enzymes, |
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Lipid digestion steps
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1) emulsification of fat drolets by bile salts 2) hydrolysis of triglycerides in emulsified fat droplets into fatty acid and monoglycerides 3)dissolving of fatty acids and monoglycerides into miscelles to produce mixed micelles
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large intestine
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absorption of water, electrolytes, vit K, B vitamins
-production of vitamin k, b vitamins via microbial organisms (microflora necesary for synthesis of Vit K, Vit B, Folic acid) -Storage of feces -No digestion occurs |
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Salivary amylase (site, source, substrate, product, ph)
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mouth, saliva, starch, maltose, 6.7
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pepsin (site, source, substrate, product, ph)
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stomach, gastric glands, protein, shorter polypeptides, 1.6-2.4
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pancreatic amylase (site, source, substrate, product, ph)
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duodenum, pancreatic juice, starch, maltose/maltriose/oilgosaccharides, 6.7-7
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trypsin, chymotrypsin, carboxypeptidase (site, source, substrate, product, ph)
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small intestine, pancreatic juice, polypeptides, amino acid/di/tripeptides, 8.0
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pancreatic lipase (site, source, substrate, product, ph)
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small intestine, pancreatic juice, triglycerides, FA/monoglycerides, 8.0
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maltase (site, source, substrate, product, ph)
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small intest, brush border of epithelial cells, maltose, glucose, 5-7
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sacrase (site, source, substrate, product, ph)
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small intest, brush border, sucrose, glucose + fructose, 5-7
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lactase (site, source, substrate, product, ph)
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small intest, brush border, lactose, glucose + galactose, 5.8-6.2
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aminopeptidase (site, source, substrate, product, ph)
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small intest, brush border, polypeptides, amino acids/di/tripeptides, 8.0
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