Complex Carbohydrates (Module 2 Lecture 2)

Question 1

Give examples of oligosaccharide heteropolymers.

Answer 1

1. Hyaluronic acid

2. Various molecules in milk and seminal fluid.

Question 2

What is a glycoconjugate?

Answer 2

An oligosaccharide either linked to a protein or a lipid.

Question 3

What are examples of oligosaccharides attached to proteins?

Answer 3

1. proteoglycan
2. glycoproteins
3. mucopolysaccharides

Question 4

What two glycoconjugates are on exterior cell membranes?

Answer 4

1. Glycoproteins (proteoglycans)

2. Glycolipids

Question 5

List seven functions of glycoconjugates.

Answer 5

1. Stabilizing protein conformation
2. Targeting intracellular or extracellular proteins
3. Antigens (blood types A, B, and +)
4. Binding sites for bacteria and toxins (pathogens)
5. Adhesion sites for viruses
6. Binding sites for lectins (adhesive proteins)
7. Suppression of immune response (including implantation and prevention of fetus rejection by mother)

Question 6

Breast-fed infants receive defense against pathogens from what oligosaccharide in breast milk?

Answer 6

sialyl-oligosaccharides.

Question 7

Explain the oligosaccharides found in seminal fluid.

Answer 7

1. Free floating oligosaccharides as well as glycoproteins and glycopeptides
2. Fucosylated derivatives of lactose are a major form.
3. Fucosylated oligosaccharides may help fertilization.

Question 8

Explain the structure of glycosaminoglycans with examples.

Answer 8

1. Negatively-charged polysaccharide with repeating dissacharide units
2. Contain either glucosamine or galactosamine.
3. Usually anionic charge comes from sulfate groups but can also come from carboxyl groups on deprotonated sugar acids.
4. Heparin is an anticoagulant with heavy sulfated groups as well as N- and O- groups.

Question 9

Explain the makeup of proteoglycans.

Answer 9

1. Made of glycosaminoglycans that are attached to long proteins.
2. Many oligosaccharide chains linked to small protein core; and carbohydrate portions can make up 95% of the molecule.

Question 10

What is another name for proteoglycan?

Answer 10

Mucopolysaccharide

Question 11

List roles of proteoglycans.

Answer 11

1. Structural component of connective tissue
2. Helps adhesion of cells to extracellular matrix
3. Heparin = anticoagulant

Question 12

Describe the structure and function of hyaluronic acid.

Answer 12

1. Unsulfated glycosaminoglycan not covalently linked to a protein.
2. Molecular weight between 10^5 and 10^7 __ (unit unknown).
3. Volume increases with hydration
4. Good lubricant and shock absorber (in joints)
5. Found in synovial fluid of joints and in the umbilical cord.