Carbohydrates of Physiological Significance

Question 1

Monosaccharides (1)

Answer 1

Sugars that cannot be hydrolyzed into simpler sugars

Triose, tetrose, pentose, hexoses, heptoses, aldoses

Used in sugar alcohols

Ex: Glucose, fructose, galactose

Question 2

Disaccharides (2)

Answer 2

Condensation of two monosaccharide units

Ex: Lactose, Maltose, Isomaltose, Sucrose, Trehalsoe

Question 3

Oligosaccharides (3-10)

Answer 3

Condensation products of 3-10 monosaccharides.

Mostly indigestible by human enzymes.

Question 4

Polysaccharides (>10)

Answer 4

Condensations of more than 10 monosaccharides

Ex: Starches, dextrins, cellulose, inulin

Question 5

D&L Isomerism of Glucose

Answer 5

Determined by orientation of -H and -OH groups around carbon 5

• OH on right = D isomer
  -OH on left = L isomer

D are most naturally occuring

Question 6

Optical Isomerism of Glucose

Answer 6

Independent of D/L isomer

Dextrorotary (+) = Light Rotates Right
Levorotary (-) = Light Rotates Left

Application: In solution, glucose is dextrorotary –> glucose

Question 7

Isomerisms of Glucose (6)

Answer 7

D/L

Optical

Pyranose & Furanose

Alpha & Beta

Epimers

Aldose-Ketose

Question 8

Pyranose & Furanose Ring

Answer 8

Pyran = 6 Carbon (most common)

Furan = 5 Carbon (6th carbon outside ring)

Question 9

Alpha & Beta Isomerism of Glucose

Answer 9

Alpha (a) = Carbon 1 UP

Beta (β) = Carbon 1 DOWN

Question 10

Epimer Isomerism of Glucose

Answer 10

Determined by configuration of -OH and -H carbons on 2,3,4

Question 11

Aldose-Ketose Isomerism of Glucose

Answer 11

Glucose = Aldehyde group on carbon 1
Fructose = Keto group on carbon 2

Question 12

Amylose

Answer 12

Glucose breakdown linear chain of glucose molecules

α-1,4 glycosidic bonds
13-20% of starch

Question 13

Amylopectin

Answer 13

Glucose breakdown branched chain of glucose molecules

α-1,4 and a-1,6 glycosidic bonds
80-87% of starch

Question 14

Polysaccharide functions

Answer 14

1. Structural or mechanical protection.
2. Energy storage.
3. Binding water to resist dehydration.

Question 15

Starch

Answer 15

i. Homopolymer (glucose is the one monosaccharide) of glucose featuring a-glycosidic bonds.

ii. Forms α-glucosidic chain called a glucosan or glucan

iii. Most important dietary carbohydrate in cereals, potatoes, legumes, vegetables

Amylose and Amylopectin are constituents of starch

Question 16

_____ are part of

Answer 16

Apoproteins needed to distinguish lipoprotein

Question 17

Glycogen

Answer 17

i. Storage polysaccharide in animals, branched
ii. More branched than amylopectin
iii. 12-15 α-D-glucopyranose residues
iv. α-1,4 and α -1,6 glycosidic bonds

Question 18

Inulin

Answer 18

Fructosan (fructose) found in tubers and roots

ii. Water soluble
iii. Not hydrolyzed = no nutritional value, we cannot digest it
iv. Application: Used to determine GFR

Question 19

Dextrins

Answer 19

i. Intermediates of starch hydrolysis

Question 20

Cellulose

Answer 20

i. Plant cell walls, insoluble
ii. β-1,4 glycosidic bonds
iii. Bacterial metabolism in the colon

iv. Application: Humans lack enzymes capable of hydrolyzing β-1,4 glycosidic bonds, so we are unable to digest cellulose (AKA fiber AKA receive energy from)

Question 21

Chitin

Answer 21

Provides structure for exoskeleton of crustaceans and insects.

ii. β-1,4 glycosidic bonds, indigestible

Question 22

Pectin

Answer 22

Starch constituent found in fruit

Question 23

Glycosaminoglycans

Answer 23

i. Amino sugars + uronic proteoglycan
ii. Component of connective tissue

iii. Application: Chondroitin Sulfate = Tx for osteoarthritis
 Heparin = Anticoagulant Drug
 Hyaluronic Acid = Wrinkle Creams
a. Binds water, retains moisture

Question 24

Carbohydrates are present within

Answer 24

Blood, Glycogen, Cell Membranes

Question 25

Excess glucose is stored as _____

Answer 25

Glycogen

Question 26

CHO in cell membranes

Answer 26

Glycoproteins, glycolipids, glycocalyx

Lipoproteins