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54 Cards in this Set
- Front
- Back
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What are the sugar constituents of Sucrose?
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Fructose and Glucose
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What are the sugar constituents of Starch?
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Glucose polymer
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What are the sugar constituents of Lactose?
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Glucose and Galactose
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What are the sugar constituents of Maltose?
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Glucose and Glucose
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What are the sugar constituents of Amylose?
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Amylose is a linear poly-maltose consisting of Glucose in 1-4 linkage
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What bond does ∂-amylase hydrolyze?
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1-4 linkage between glucose units of starches.
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What inhibits ∂-amylase in the stomach?
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HCl
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What prevents the denaturing of ∂-amylase, due to stomach acid?
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Bicarbonate
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Where is ∂-amylase actively hydrolyzing starch?
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Mouth and intestines
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What is a glycosidase?
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An enzyme that hydrolyzes bonds between sugars.
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What is an endonuclease?
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It is an enzyme that hydrolyzes internal bonds of a complex, e.g., ∂-amylase.
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Will ∂-amylase hydrolyze isomaltose (an isomer of maltose)?
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No, since isomaltose has a 1-6 linkage. It requires isomaltase
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What is the name of the branch of glucose polymer that is connected by a ∂, 1-6 linage?
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Amylopectin
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What type of bond holds the fructose and glucose together in sucrose?
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Alpha 1-2, linkage
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What type of bond holds the galactose and glucose together in lactose?
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ß, 1-4 linkage
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What is the function of the sucrase-isomaltase complex? And where is it found?
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It metabolizes sucrose and isomaltose and is found in membrane of the gut.
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What is the function of glucoamylase?
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It hydrolyzes ∂, 1-4 linkage between glucose-glucose in maltose.
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What is the function of lactase?
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It hydrolyzes ß, 1-4 linkage between galactose-glucose in lactose.
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Why does the lack of lactase (ß-glycosidase) cause diarrhea?
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If the enzyme that breaks up lactose is present on the brush border of the intestines then the galactose and glucose are absorbed, if not bacteria breaks it and you get more molecules in the gut… thus water flows out of the cell and into the gut.
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What are the products resulting in the gut in the absence of lactase?
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Galactose, glucose, CO2, CH4, H2
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What is the conclusive measurement of lactase deficiency?
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H2 content of exhalation… produced by microbial flora.
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How long do the symptoms of lactase deficiency present after consuming milk?
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45-60 minutes
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What is a channel protein?
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A protein that makes a hole in the membrane and facilitate the flow of molecules down their concentration gradient.
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What is gated channel?
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A protein channel that can be opened or closed in response to metabolic signals.
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What is involved in facilitative diffusion?
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Stuctrural change in the protein in response to substrate specificity.
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What type of curve represents simple diffusion?
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Linear
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In facilitated diffusion, what type of kinetics is observed?
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Saturation kinetics (hyperbolic curve), which will show increases in diffusion as concentration increases, then tapper off, then stop increasing as the protein reaches it V-max.
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In a hyperbolic cure (facilitated diffusion), where do you find the Km?
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x-int of the _ v-max.
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Which has higher affinity, low or high Km?
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Low
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a.
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RBC, or barriers (blood/brain)
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b.
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Intestines, Liver, kidney, pancreas
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b.
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Glut 2
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a.
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Which Glut has higher affinity and lower capacity?
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b.
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What effect will this have?
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b.
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Glucose will cross the barrier whenever it is near.
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a.
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Which Glut has lower affinity and higher capacity?
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b.
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What effect will this have?
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b.
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Glucose will only be taken up when [glucose] are high.
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What can the body do to modulate the V-max?
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Make more transporters
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Can V-max and Km be modulated?
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Yes
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What relevance does the Na+/K+-ATPase have to glucose transport in the intestines, from the gut into the cells? (hint:coupled transport)
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a. 3 Na+ out of the cell (against its gradient and building up in the cell) and eventually will flow into the bloodstream
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Detail how cholera causes diarrhea.
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a.
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b.
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A-subunit binds to adenylate cyclase
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c.
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Adenylate cyclase will constitutively produce cAMP
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d.
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cAMP activates PKA
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e.
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PKA stimulate Chloride transport out of the cell… water follows into the gut… via the CFTR.
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What is CFTR?
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Cystic fibrosis transmembrane regulator protein
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What is the treatment of cholera?
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Water, sodium and glucose… taking advantage of the Na/K cotransport system.
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a.
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What role does G-protein play in regular signal for the CFTR?
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b.
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In normal function, what inhibited constitutive synthesis?
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b.
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GTPase hydrolyzes “it”
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With respect to chlorine channels, what is the sequence of events after cAMP is produced?
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a.
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b.
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PKA stimulate chlorine channel transport, via the CFTR, into the luman
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What does a high Vmax indicate?
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The enzyme works fast.
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