Carbohydrate Digestion

Question 1

True or false? Monosaccharides can be hydrolyzed into simple sugar

Answer 1

false; cannot

Question 2

In regards to monosaccharides, ____ form stable ring structures in solution

Answer 2

hexoses

Question 3

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

Answer 3

anomeric; 2

Question 4

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

Answer 4

beta; alpha

Question 5

Anomeric-OH of one monosaccharide can react with another on a second monosaccharide, giving rise to a _____

Answer 5

glycosides

Question 6

The linkage between monosacchardies is called _____ ____

Answer 6

glycosidic linkage

Question 7

____ contains two alpha-D-glucose molecules linked together by alpha 1,4 glycosidic linkage

Answer 7

maltose

Question 8

____ is formed by linking alpha-D-glucose with Beta-D-fructose to give a 1,2 glycosidic link

Answer 8

sucrose

Question 9

____ is formed by joining Beta-D-galactose to alpha-D-glucose to give a Beta 1,4 glycoside

Answer 9

Lactose

Question 10

This type of polysaccharide is made up of the same monosaccharide units: starch, glycogen, and cellulose

Answer 10

homopolysaccharides

Question 11

This type of polysaccharide is made up of more than one kind of monosaccharide: condition sulfate, hyaluronic acid, and heparin

Answer 11

heteropolysaccharides

Question 12

This type of polysaccharide is made of carbohydrates that are covalently attached to protein and lipid molecules: proteoglycans, glycoproteins, and glycolipids

Answer 12

glycoconjugates

Question 13

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)

Answer 13

starch

Question 14

This homopolysaccharide is a storage form of glucose in animals. It is more highly branched than amylopectin

Answer 14

glycogen

Question 15

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

Answer 15

cellulose

Question 16

This is the most abundant heteropolysaccharide in the body. Hint: highly negative charged molecules

Answer 16

GAGs

Question 17

This type of glycoconjugate is found in the extracellular matrix and consist of a GAG chain linked to a core protein

Answer 17

proteoglycan

Question 18

What are some examples of glycoproteins (glycoconjugate)

Answer 18

antibodies, human blood group antigens, hormones FSH, LH, and TSH

Question 19

Where are glycolipids present?

Answer 19

in nerve tissues (brain) and in cell membrane (gangliosides)

Question 20

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 ___

Answer 20

facilitated; liver

Question 21

Digestion requires what two enzymes?

Answer 21

1. amylase (salivary glands and pancreas)

2. oligosaccharidases (mucosal brush border enzymes)

Question 22

For the following enzyme, give the activity, substrate, and product: maltase

Answer 22

activity: exoglucosidase alpha 1,4 only
substrate: malto-oligosaccharides
product: glucose

Question 23

For the following enzyme, give the activity, substrate, and product: sucrase

Answer 23

activity: hydrolyzes sucrose and maltase activity
substrate: sucrose malto-oligosaccharides
product: glucose and fructose

Question 24

For the following enzyme, give the activity, substrate, and product: isomaltase

Answer 24

activity: alpha 1,6 bonds
substrate: alpha-dextrins
product: glucose

Question 25

For the following enzyme, give the activity, substrate, and product: lactase

Answer 25

activity: beta-glycosidase
substrate: lactose
product: glucose and galactose

Question 26

For the following enzyme, give the activity, substrate, and product: trehalase

Answer 26

activity: trehalose
substrate: trehalose
product: glucose

Question 27

Describe the process of absorption of monosaccharides

Answer 27

1. cotransport molecules in the brush border bind Na+ ions and glucose/galactose
2. Na+ ions pass into cell, down conc. gradient (facilitated diffusion)
3. Na+ ions are actively transported in exchange for K+ ions (active transport)
4. electrochemical gradient caused by active transport is used to transport glucose/galactose not cell against their conc. gradients
5. glucose/galactose moves out of other side of epithelial cell by facilitated diffusion

Question 28

For the following Glucose transporter, give the location and characteristics: GLUT1

Answer 28

many tissues; basal transport, blood brain barrier

Question 29

For the following Glucose transporter, give the location and characteristics: GLUT2

Answer 29

liver, islet B cells, kidney, small intestine; low affinity, high capacity

Question 30

For the following Glucose transporter, give the location and characteristics: GLUT3

Answer 30

neurons; basal transport in neurons

Question 31

For the following Glucose transporter, give the location and characteristics: GLUT4 (most important)

Answer 31

skeletal muscle, heart, and fat; insulin responsive transport

Question 32

For the following Glucose transporter, give the location and characteristics: GLUT5

Answer 32

small intestine, sperm, testes; fructose transport