4.4 Complex Carbohydrates

Question 1

Complex Carbohydrate

Answer 1

• includes all carbohydrates with at least two sugar molecules linked together
• Ex: disaccharides, oligosaccharides, and
  polysaccharides).

Question 2

How do disaccharides form?

Answer 2

Glycosidic bonds formed between hydroxyl groups of two monosaccharides

Question 3

Glycosidic linkages

Answer 3

• nonspecific in that the anomeric carbon of a cyclic sugar can react with any hydroxyl group
• linkages are named for the configuration of the anomeric carbon and the numbers of the hydroxyl-containing carbons
  involved in the linkage (α-1,6 glycosidic bond) the α-anomeric carbon of the first glucose (C-1) attaches to C-6 of the second glucose
• If formed between two anomeric carbons (α,α-1,1 linkage)
• Forming bonds with α & β make different molecules and different names. (β- 1,6 is not the same as α - 1,6)
• polymer formation can either be linear or branched

Question 4

Most important disaccharides?

Answer 4

• sucrose, lactose, and maltose
• commonly produced in the cell by enzymatic activity

Question 5

Polysaccharides

Answer 5

• long chains of monosaccharides linked together by glycosidic bonds
• Ex. cellulose, starch, and glycogen; all composed of the same monosaccharide, D-glucose; differ in configuration about the anomeric carbon and the position of glycosidic bonds
• debranching enzymes help degrade the polysaccharide chain

Question 6

Homopolysaccharide

Answer 6

• A polysaccharide composed entirely of glucose (or any other monosaccharide)

Question 7

Heteropolysaccharide

Answer 7

• a polymer made up of more than one type of monosaccharide

Question 8

Branching

Answer 8

• happens when an internal monosaccharide in a polymer chain forms at least two glycosidic bonds, allowing branch formation

Question 9

Cellulose

Answer 9

• the main structural component of plants
• a chain of β-d-glucose molecules linked by β-1,4 glycosidic bonds, with hydrogen bonds holding the actual polymer chains together for support.
• Humans are not able to digest cellulose, lack the cellulase enzyme

Question 10

Starches

Answer 10

• polysaccharides that are more digestible by humans because they are linked α-d-glucose monomers
• Iodine detects starch
• Ex: Amylose & Amylopectin

Question 11

Difference between Alpha and Beta Amylase?

Answer 11

• Beta cleaves at nonreducing end
• Alpha cleaves randomly along the chain

Question 12

Glycogen

Answer 12

• a carbohydrate storage unit in animals
• has more α-1,6 glycosidic bonds (approximately one for every 10 glucose molecules) than starch.
• highly branched compound
• branching optimizes the energy efficiency of glycogen and makes it more soluble in solution, thereby allowing more glucose to be stored in the body
• the branching pattern allows enzymes that cleave glucose from glycogen, such as glycogen phosphorylase, to work on many sites within the molecule simultaneously.

Question 13

Glycogen phosphorylase

Answer 13

• functions by cleaving glucose from the nonreducing end of a glycogen branch and phosphorylating it, thereby producing glucose 1 phosphate, which plays an important role in metabolism.