Carbohydrate Digestion Flashcards
True or false? Monosaccharides can be hydrolyzed into simple sugar
false; cannot
In regards to monosaccharides, ____ form stable ring structures in solution
hexoses
The cyclization of a monosaccharide introduces a new asymmetric carbon at carbon 1, which is known as a ____ carbon. This allows for ___ isomers called anomers
anomeric; 2
In regards to anomers, if the OH group is above the plane of ring, it is called ___ anomer, while if the OH group is below the plane of ring, it is called _____ anomer
beta; alpha
Anomeric-OH of one monosaccharide can react with another on a second monosaccharide, giving rise to a _____
glycosides
The linkage between monosacchardies is called _____ ____
glycosidic linkage
____ contains two alpha-D-glucose molecules linked together by alpha 1,4 glycosidic linkage
maltose
____ is formed by linking alpha-D-glucose with Beta-D-fructose to give a 1,2 glycosidic link
sucrose
____ is formed by joining Beta-D-galactose to alpha-D-glucose to give a Beta 1,4 glycoside
Lactose
This type of polysaccharide is made up of the same monosaccharide units: starch, glycogen, and cellulose
homopolysaccharides
This type of polysaccharide is made up of more than one kind of monosaccharide: condition sulfate, hyaluronic acid, and heparin
heteropolysaccharides
This type of polysaccharide is made of carbohydrates that are covalently attached to protein and lipid molecules: proteoglycans, glycoproteins, and glycolipids
glycoconjugates
This homopolysaccharide is a storage form of glucose and is found in plants. It is made of polymers of alpha linked glucose. There are 2 types: amylose (1,4) and amylopectin (1,4 and 1,6)
starch
This homopolysaccharide is a storage form of glucose in animals. It is more highly branched than amylopectin
glycogen
This homopolysaccharide is a chief constituent of plant cell walls. It is a liner homopolymer composed of Beta-D-glucose units linked by B-1,4 linkage. Animals lack the enzymes necessary to hydrolyze this linkage and can’t digest this homopolysaccharide
cellulose
This is the most abundant heteropolysaccharide in the body. Hint: highly negative charged molecules
GAGs
This type of glycoconjugate is found in the extracellular matrix and consist of a GAG chain linked to a core protein
proteoglycan
What are some examples of glycoproteins (glycoconjugate)
antibodies, human blood group antigens, hormones FSH, LH, and TSH
Where are glycolipids present?
in nerve tissues (brain) and in cell membrane (gangliosides)
In regards to digestion of carbs, polysaccharides are broken down into monosaccharides (glucose, galactose) which are then absorbed by the intestinal lining by ____ diffusion. they are then transported through the venous system capillaries to the ___
facilitated; liver
Digestion requires what two enzymes?
- amylase (salivary glands and pancreas)
2. oligosaccharidases (mucosal brush border enzymes)
For the following enzyme, give the activity, substrate, and product: maltase
activity: exoglucosidase alpha 1,4 only
substrate: malto-oligosaccharides
product: glucose
For the following enzyme, give the activity, substrate, and product: sucrase
activity: hydrolyzes sucrose and maltase activity
substrate: sucrose malto-oligosaccharides
product: glucose and fructose
For the following enzyme, give the activity, substrate, and product: isomaltase
activity: alpha 1,6 bonds
substrate: alpha-dextrins
product: glucose
For the following enzyme, give the activity, substrate, and product: lactase
activity: beta-glycosidase
substrate: lactose
product: glucose and galactose
For the following enzyme, give the activity, substrate, and product: trehalase
activity: trehalose
substrate: trehalose
product: glucose
Describe the process of absorption of monosaccharides
- cotransport molecules in the brush border bind Na+ ions and glucose/galactose
- Na+ ions pass into cell, down conc. gradient (facilitated diffusion)
- Na+ ions are actively transported in exchange for K+ ions (active transport)
- electrochemical gradient caused by active transport is used to transport glucose/galactose not cell against their conc. gradients
- glucose/galactose moves out of other side of epithelial cell by facilitated diffusion
For the following Glucose transporter, give the location and characteristics: GLUT1
many tissues; basal transport, blood brain barrier
For the following Glucose transporter, give the location and characteristics: GLUT2
liver, islet B cells, kidney, small intestine; low affinity, high capacity
For the following Glucose transporter, give the location and characteristics: GLUT3
neurons; basal transport in neurons
For the following Glucose transporter, give the location and characteristics: GLUT4 (most important)
skeletal muscle, heart, and fat; insulin responsive transport
For the following Glucose transporter, give the location and characteristics: GLUT5
small intestine, sperm, testes; fructose transport
