Carbohydrates

Question 1

Role of carbohydrates

Answer 1

• a major source of energy
• half or more of the total caloric intake

Question 2

Two major

Answer 2

1. Simple carbohydrates => monosaccharides, disaccharides
2. Complex carbohydrates => oligosaccharides, polysaccharides

Question 3

Monosaccharides

Answer 3

Glucose, Fructose, Galactose
Classification -> position of functional carbonyl-group
- aldose contains aldehydes group
- ketone contains a ketone group
- number of carbons: aldohexose, ketohexose, ketopentose

Question 4

How are carbohydrates optically active?

Answer 4

• presence of one or more chiral carbon atoms in the molecules
  = Polarized light can pass through

Question 5

Pentose

Answer 5

• little source of dietary energy
• from hexose precursors
• transforms into metabolic important compounds

Question 6

Disaccharides

Answer 6

• two sugars
• Maltose => formed from partial hydrolysis of starch
• alpha lactose, sucrose

Question 7

Oligosaccharides

Answer 7

• digested -> utilized
• raffinose (trisaccaride)
• stachyose (tetrasaccharide)
• verbacose (pentasaccharide)
• monosaccharides

Question 8

Dextrins

Answer 8

oligo- or polysaccharides
- composed of glucose
- additives in foods, pharmaceuticals and nutritional supplements
- from hydrolysis of starch or glycogen

Question 9

Polysaccharides

Answer 9

account for nearly 50% of dietary carbohydrate intake
- starch
- glycogen
- cellulose

Question 10

What are compounds meant by ‘sugar’?

Answer 10

sugar = table sugar = sucrose, saccharose

Question 11

What are ‘free sugars’?

Answer 11

all monosaccharides and disaccharides added to foods by the manufacturer, cook, or consume plus naturally present

Question 12

How do saliva enzymes digest polysaccharides?

Answer 12

• alpha 1-4 amylase (hydrolyzes alpha 1-4 glycosidic bonds) = glycosidase (breakdown of starch, glycogen)

Question 13

Pancreatic alpha 1-4 amylase

Answer 13

• fast and efficient enzyme
• responsive to diet composition
• high-carbohydrate diet