Carbohydrates

Question 1

Characteristics of monosaccharides

Answer 1

They are colourless, crystalline, soluble in water, non soluble in non polar solvents

Question 2

Name the carbohydrate that isn’t a chiral molecule

Answer 2

Dihydroxyacetone

Question 3

Epimers? Eg?

Answer 3

Sugars that are closely related but only have different stereochemistry at one carbon
Eg. D glucose and D galactose
D glucose and D mannose

Question 4

Who forms pyran ring and who forms furan ring

Answer 4

Pyran is formed by hemiacetal and hemiketal if the carbon atom binds to C6
Furan formed when hemiketal binds to C5

Question 5

Anomers

Answer 5

The position of the hydroxyl group of anomeric carbon
Above the plane then beta, below the plane then alpha

Question 6

Mutarotation

Answer 6

When the sugar interconverts its state from alpha to beta and changes its specific optical rotation to reach equilibrium in aqueous solution

Question 7

Glycoside and eg

Answer 7

Acetal in which a sugar is bonded through its anomeric carbon by glycosidic bond. Eg. Streptomycin and ouabain

Question 8

Types of sugar acids. What occurs? Oxidation or reduction? In which sugar does it occur?

Answer 8

Aldonic, aldaric and uronic
Oxidation
Aldehydes

Question 9

Sugar alcohol? What occurs? Oxidation or reduction. Eg

Answer 9

Carbonyl group in aldehyde or ketone get reduced to hydroxyl group.
Eg. Sorbitol and xylitol

Question 10

Osazone formed by?

Answer 10

D Glucose, D Mannose and D Fructose

Question 11

Disaccharides are formed by which bond?

Answer 11

O glycosidic bond

Question 12

How are sucrose, galactose and maltose formed?

Answer 12

Sucrose - Glucose and Fructose ( a1 to 2b)
Galactose - Glucose and Glucose (b1 to 4)
Maltose - Glucose and Glucose ( a1 to 4)

Question 13

How are trehalose, cellobiose and gentibiose formed

Answer 13

Trehalose - glucose and glucose (a1 to a1)
Cellobiose - glucose and glucose (b1 to 4)
Gentibiose - glucose and glucose (b1 to 6)

Question 14

Hydrolysis of sucrose

Answer 14

Sucrose is dextrorotatory. When hydrolyzed by hot dilute acid forms D Glucose and D Fructose. D Fructose has more specific rotation and is levorotatory. Hence the product formed is levorotatory. So this is called invert sugar

Question 15

Polysaccharides are also known as?

Answer 15

Glycans

Question 16

Starch?

Answer 16

Branched chain of D Glucose. Formed by amylopectin and amylose. Storage of glucose in plants
Bonds a1 to 4 and branching a1 to 6

Question 17

Amylose and amylopectin solubility in water

Answer 17

Amylose soluble and amylopectin insoluble

Question 18

Glycogen

Answer 18

Major storage form of carbohydrates in animals. Found in liver and muscle.
Branched amylopectin
Bond a1 to 4 and branching a1 to 6

Question 19

Cellulose

Answer 19

Unbranched linear homopolysaccharide of D Glucose. Most abundant organic compound.
Bond b1 to 4

Question 20

Chitin

Answer 20

Linear homopolysaccharide of N acetyl D glucosamine.
Bond b1 to 4

Question 21

Glycosaminoglycans

Answer 21

Negatively charged, unbranched heteropolysaccharide of amino sugar and acidic sugar.

Question 22

Which GAG isn’t attached to any protein

Answer 22

Hyaluronic acid

Question 23

Which GAG doesn’t have any acidic sugar

Answer 23

Keratin sulphate

Question 24

Which GAG is responsible for corneal transparency

Answer 24

Keratin sulphate

Question 25

Peptidoglycan/ murein made of?

Answer 25

N acetylglucosamine and N acetylmuramic acid

Question 26

Inulin formed of

Answer 26

D Fructose
B2 to 1

Question 27

Dextran formed of?

Answer 27

D Glucose
a1 to 6

Question 28

Glycoconjugate

Answer 28

Carbohydrates joined to non carbohydrates.

Question 29

Reducing and non reducing

Answer 29

Every sugar is reducing sugar except sucrose and trehalose

Question 30

Callose

Answer 30

Homopolysaccharide, b 1,3 glucose