Carbs/sugars

Question 0

Polysaccharides

Answer 0

Long chain monosaccharides

Question 1

Predominant form of sugar in humans

Answer 1

D

Question 2

Disaccharides

Answer 2

Two monosaccharides inked by a glycosidic linkage

Question 3

Monosaccharide classifications

Answer 3

Functional groups:
Aldoses - alhedyde on C1
Ketoses - keto on C2

Number of Carbons:
Trioes, 3C
Tetroses 4C
Pentoses
Hexoses
Heptoses

Question 4

Clinical conditions of sugar in urine

Answer 4

Diabetes mellitus: high blood glucose levels >170-180mg

Fructosuria & hereditary fructose intolerance:

Galactosemia: inherited disorder of galactose metabolism.

Question 5

Clinitest

Answer 5

(Benedict’s test)

Detects reducing property of aldehyde and keto groups in monosaccharides.

Question 6

Aldose sugars

Answer 6

Glyceraldehyde 3C
Erythrose 4C
Ribose & xylose 5C
GLUCOSE, galactose, Mannose 6C

Question 7

Keto sugars

Answer 7

Dihydroxyacetone 3C
Ribulose & Xyulose 5C
Fructose 6C
Sedoheptulose 7C

Question 8

Alpha and Beta anomers of glucose

Answer 8

Alpha: OH off C1 below the plane
Beta: OH off C1 above the plane

Question 9

Pyranoses and Furanoses

Answer 9

Pyranoses: 6 membered ring of 5C and 1 Oxygen

Furanoses: 5 membered ring of 4C and 1 Oxygen

Question 10

Polyols

Answer 10

Sugar Alcohols- obtained by reduction of sugar, changing the aldehyde group to a hydroxyl group. Sorbitol & Galactitol

Question 11

Epimers

Answer 11

Carbohydrate isomers that differ in the configuration around one of the asymmetric C-atoms.

• Glucose and galactoseare C-4 epimers
• Glucose and mannose are C-2 epimers

Question 12

Galactitol

Answer 12

formed from galactosein the lens in children with untreated galactosemia

Question 13

Sorbitol

Answer 13

sugar alcohol formed from glucose by aldose reductase when the blood glucose level is elevated for a prolonged period of time.

Can cause damage to retinal and neural cells.

Question 14

Lactose

Answer 14

glucose + Galactose with a β1→4 glycosidic linkage

Cleaved by lactase in the intestinal tract

Question 15

Sucrose

Answer 15

Glucose + Fructose (non-reducing sugar)
Alpha-1-2 glycosidic bond
Cleaved by sucrase in the intestines

To be avoided in children with hereditary fructose intolerance

Question 16

Maltose

Answer 16

2 glucose units
α1→4 glycosidic linkage
Reducing sugar
cleaved by maltase in the intestine

Question 17

Homopolysaccharides vs. Heteropolysaccharides

Answer 17

Homo: similar monosaccharide units Ex. Starch
Hetero: different monosaccharide units Ex. GAGs

Question 18

Glycogen

Answer 18

storage polysaccharide in human liver and muscle as cytosolic glycogen granules for secondary energy storage.

linear chain are linked by α1→4 glycosidic linkages
branch point are linked by α1→6 glycosidic linkages

Chain synthesis caused by increased glucose and insulin in the blood signaling uptake into liver and muscle cells.

Chain degredation by glycogen phosphorylase freeing glucose in response to glucagone and decreased glucose and insulin.

Question 19

Cellulose

Answer 19

glucose units linked by β1→4 glycosidiclinkages

β1→4 glycosidiclinkages in cellulose cannot be cleaved by digestive enzymes in the human gut

A dietary fiber

Question 20

Starch

Answer 20

Plant Polymer of glucose.

Two components:
•Amylose(linear unbranchedpolymer of glucose alpha 1,4 links)

•Amylopectin(branched polymer of glucose alpha 1,6 links)

digested by salivary and pancreatic amylase

Question 21

O-linked glycoproteins

Answer 21

–Glycosylationon the OH group of Ser/Thr
–Often found as extracellular proteins or as membrane bound proteins
–Glycangroups always face extracellular side

Question 23

N-Linked Glycoproteins

Answer 23

Linked to an -NH2 group
–Glycosylationon the Asn residue (not Gln)
–Either of two types (high mannose, or complex)

Question 24

Hyperglycermia

Answer 24

High blood glucose levels.

Can result in the formation of:
Sorbitol
Glycated Hemoglobin
hyperglycemic coma due to the osmotic affect of glucose pulling H2O from neural tissue.