Introduction to Carbohydrates

Question 1

What are the three types of carbohydrates?

Answer 1

Monosaccharides, disaccharides, polysaccharides

Question 2

What do monosaccharides consist of?

Answer 2

3–6 carbon atoms, a carbonyl group (aldehyde or ketone), and several hydroxyl groups

Question 3

What are aldoses?

Answer 3

Monosaccharides with an aldehyde group and many hydroxyl groups

Question 4

What are ketoses?

Answer 4

Monosaccharides with a ketone group and many hydroxyl (-OH) groups

Question 5

What determines if a carbon is a chiral centre?

Answer 5

If it has four different substituent groups

Question 6

What is a Fischer projection?

Answer 6

A representation of carbohydrates with the most oxidized group at the top and chiral carbons at line intersections

Question 7

How do L and D notations work?

Answer 7

The -OH group on the chiral carbon farthest from the carbonyl group is left for L-form and right for D-form

Question 8

What is D-glucose?

Answer 8

An aldohexose (C₆H₁₂O₆), found in fruits and honey, known as blood sugar

Question 9

What is the difference between D-glucose and D-galactose?

Answer 9

Galactose must be converted to glucose first before the body can use it

Question 10

What is galactosemia?

Answer 10

A condition caused by lack of enzymes for galactose metabolism, leading to toxic intermediate accumulation

Question 11

How do monosaccharides form cyclic structures?

Answer 11

Hydroxyl on C-5 reacts with aldehyde or ketone group

Question 12

What is the difference between α-D-glucose and β-D-glucose?

Answer 12

α has the OH on C1 down; β has it up

Question 13

What happens when α- and β-D-glucose are in solution?

Answer 13

They interconvert, forming a dynamic equilibrium with a trace open-chain form

Question 14

Which is the simplest sugar?

Answer 14

Glyceraldehyde

Question 15

Which is the sweetest sugar?

Answer 15

Fructose

Question 16

Which sugar is part of milk sugar?

Answer 16

Galactose

Question 17

Which sugar is most important in metabolism?

Answer 17

GlucoseW

Question 18

which sugar is used in nucleic acids?

Answer 18

RiboseW

Question 19

What does sucrose comprise?

Answer 19

Glucose + fructose

Question 20

What does maltose comprise of?

Answer 20

Glucose + glucose

Question 21

What does lactose comprise of?

Answer 21

Glucose + galactose

Question 22

What is lactose?

Answer 22

A disaccharide of β-D-galactose and α- or β-D-glucose with a β-1,4-glycosidic bond

Question 23

What is lactose intolerance?

Answer 23

Inability to digest lactose due to lack of lactase enzyme

Question 24

What is the most common carbohydrate homopolymer in animal cells?

Answer 24

Glycogen

Question 25

Where is glycogen found?

Answer 25

In liver and muscle

Question 26

What linkages does glycogen have?

Answer 26

α-1,4 and α-1,6-glycosidic bonds

Question 27

What is starch composed of?

Answer 27

Amylose and amylopectin

Question 28

What breaks down starch?

Answer 28

α-amylase from salivary glands and pancreas

Question 29

What is cellulose?

Answer 29

A polysaccharide with β-1,4 linkages; mammals lack cellulases to digest it

Question 30

What is a reducing sugar?

Answer 30

A sugar that reduces inorganic ions like Cu²⁺

Question 31

Are all monosaccharides reducing sugars?

Answer 31

Yes

Question 32

What test determines glucose in blood?

Answer 32

Fehlings reaction

Question 33

How does glucose enter red blood cells?

Answer 33

In a non-insulin dependent manner

Question 34

What is HbA₁c?

Answer 34

A covalent adduct formed by glucose attaching to the NH₂ terminal of hemoglobin β-chain

Question 35

What does HbA₁c reflect?

Answer 35

Average blood glucose levels over ~120 days (RBC lifespan)

Question 36

What is glycation?

Answer 36

Non-enzymatic addition of sugar to a protein