Chap 10- Polysaccharides And Biomterials

Question 1

What are monosaccharides?

Answer 1

Simple carbohydrates. Aldehydes of ketones that have two or more hydroxyl groups. The smallest monosaccharides are dihydroxyacetone and glyceraldehyde

Question 2

What are polysaccharides?

Answer 2

Complex carbohydrates- polymers of covalently linked monosaccharides. Can be two or more monosaccharides linked together.

Question 3

What is glucose used for?

Answer 3

Essential energy source for pretty much all forms of life

Question 4

What is fructose used for?

Answer 4

Commonly used as a sweetener that is converted into glucose derivatives inside the cell.

Question 5

Constitutional isomers def

Answer 5

Identical molecular formula but differ in how the atoms are ordered.

Question 6

Stereoisomers def

Answer 6

Isomers that differ in spacial arrangement.
Ex. The stereoisomers of glyceraldehyde D and L

Question 7

Enantiomers def

Answer 7

Stereoisomers that are mirror images of each other.

Question 8

Diastereoisomers def

Answer 8

Isomers that are not mirror images of each other

Question 9

Epimers def

Answer 9

Sugars that are diastereoisomers that differ in configuration at only one single asymmetric center.

Question 10

Anomer def

Answer 10

A diastereoisomeric form of sugars where an additional asymmetric center is created when a cyclic hemiacetal is formed.

Question 11

Alpha designation

Answer 11

The hydroxyl group attached to C1 is below the plane of the ring

Question 12

Beta designation

Answer 12

The hydroxyl group on C1 is above the plane of the ring

Question 13

What is the name of the bond formed between the anomeric carbon atom of glucose and the O of alcohol? What about bond with nitrogen of an amine?

Answer 13

A glycosidic bond, specifically O-glycosidic bond and the product is called a glycoside.
With nitrogen, N-glycosidic bond.

Question 14

Oligosaccharides def

Answer 14

They are built by the linkage of two or more monosaccharides by O-glycosidic bonds.

Question 15

What is the linkage called in maltose?

Answer 15

a-1,4-glycosidic bond

Question 16

What is the name of the enzymes that form glycosidic bonds

Answer 16

Glycosyltransferases. They help form glycosidic bonds and oligosaccharides.

Question 17

Disaccharide def and examples

Answer 17

Consists of two sugars joined by an O-glycosidic bond
Ex sucrose, lactose and maltose

Question 18

What enzyme is used to hydrolyze lactose into its two monomers, what are the monomers?

Answer 18

Lactase. Galactose and glucose

Question 19

Maltose is hydrolyzed by what enzyme into what?

Answer 19

Maltase, into glucose

Question 20

What do polysaccharides play vital roles in?

Answer 20

In energy storage and maintaining the structural integrity of an organism.

Question 21

What is a homopolymer?

Answer 21

A polysaccharides with all the same monosaccharides.

Question 22

What is the most common homopolymer in animals and where are they found?

Answer 22

Glycogen. Present in most of our tissues but most common in muscle and liver.

Question 23

What is the nutritional reservoir in plants?

Answer 23

Starch

Question 24

What are the two forms of starch?

Answer 24

1. Amylose, the unbranched type. Consists of glucose residues in a-1,4 linkage.
2. Amylopectin, the branched form has one a-1,6 linkage per 30 a-1,4 linkage.

Question 25

Examples of starches that we eat

Answer 25

Wheat, potatoes, rice.

Question 26

What enzyme hydrolyzes starches?

Answer 26

a-amylase hydrolyzes amylopectin, amylose, and glycogen rapidly. Amylase is secreted by the salivary glands and the pancreas.

Question 27

What is cellulose, and what is its role?

Answer 27

Cellulose is a major polysaccharides of glucose that is found in plants and its role is structural component of the plant cell wall. Among the most abundant organic compounds in the biosphere. Cellulose is an unbranched polymer of glucose joined by b-1,4 linkages.

Question 28

What does the beta conformation of cellulose allow?

Answer 28

The b configuration allows cellulose to form very long, straight chains. Forms very long, straight chains, optimal for constructing fingers with high tensile strength.

Question 29

What does the alpha confirmation of glycogen and starch allow?

Answer 29

The alpha conformation for glycogen and starch produce a hollow helix, well suited to the formation of a more compact, accessible store of sugar.

Question 30

What is a glycoprotein?

Answer 30

A carbohydrate group covalently attached to a protein

Question 31

What are the three classes of glycoproteins?

Answer 31

1. Glycoprotein- the protein constituent is the largest component by weight. Many are components of cell membranes. 2. Proteoglycans- the protein component is conjugated to a polysaccharides, a glycosaminoglycan. Carbohydrates make up a larger percent y weight. Function as structural components and lubricants. 3. Mucoproteins- predominately carbohydrate. A key component of mucus, serves as lubricants.

Question 32

2 ways that a glycosidic bond links a carbohydrate to the protein in glycoproteins

Answer 32

1. To the amide nitrogen in asparagine (N-linkage) 2. To the hydroxyl oxygen in serine or threonine (O-linkage)

Question 33

Glycan-binding proteins def

Answer 33

Bond specific carbohydrate structures on neighbouring cell surfaces. They are ubiquitous and no living organisms have been found that lack these key proteins.

Question 34

Lectins def

Answer 34

Class of glycan binding proteins. The interaction of lectins with their carbohydrate partners is another example of carbohydrates being information rich molecules that guide biological processes, Lectins promote interactions between cells. The lectins in the surface of one cell interact with carbohydrates displayed on another cell.

Question 35

Compare the number of reducing and non reducing ends in a molecule of glycogen. Which end would you expect most metabolism to occur?

Answer 35

Each glycogen molecule has one reducing end, whereas the number of non reducing ends is determined by the number of branch gets, a-1,6-linkages. Because they’re are more reducing ends, all of the degradation and synthesis of glycogen takes place at the non reducing ends, maximizing the rate of degradation and synthesis.

Question 36

Compare the structures of glycogen and starch

Answer 36

Glycogen is a polymer of glucose linked by a-1,4-glycosidic bonds with branches formed approximately every 12 units by a-1,6-glycosidic bonds. Starch consists of two polymers of glucose. Amylose is a straight chain polymer formed by a-1,4-glycosidic bonds. Amylopectin is similar to glycogen, but amylopectin has fewer branches, one per 30 units.

Question 37

Account for the different structures of glycogen and cellulose

Answer 37

Cellulose is a linear polymer of glucose joined by b-1,4-linkages. Glycogen is a branched polymer with the Main chain being formed by a-1,4-glycosidic bonds. The b-1,4linkages allow the formation of a linear polymer, ideal for structural roles. The a-1,4-linkages of glycogen form alpha helix structures, which allows the storage of many glucose moieties in a small place

Question 38

What is the function of the carbohydrate moiety that is attached to EPO?

Answer 38

The attachment of the carbohydrate allows EPO to stay in circulation longer and thus to function for longer periods of time than one that doesn’t have one.

Question 39

Why are polysaccharides considered information-rich molecules?

Answer 39

The wide array of possible linkages between carbohydrates in concert with the wide variety of monosaccharides and their many isomeric forms makes complex carbohydrates information-rich molecules.