Ch. 13: Carbohydrate Structure and Function

Question 1

What are the three main groups of carbohydrates?

Answer 1

Simple sugars, polysaccharides, glycoconjugates

Question 2

Three types of simple sugars

Answer 2

Monosaccharides, disaccharides, oligosaccharides

Question 3

Two types of polysaccharides

Answer 3

Glucose homopolymers, disaccharide heteropolymers

Question 4

Three types of glycoconjugates

Answer 4

Glycoproteins, proteoglycans, glycolipids

Question 5

D vs. L-Oriented Sugars

Answer 5

L- last chiral group is on the left, D - last chiral group is on the right (most abundant in nature)

Question 6

Alpha vs. Beta glycosidic linkages

Answer 6

If the H group lost from the hydroxyl is below the line of symmetry, it’s alpha; above the line of symmetry, and it’s beta

Question 7

Glycosyltransferases

Answer 7

Enzymes that catalyze the formation of the glycosidic linage to form a glycoside

Question 8

Glycobiology

Answer 8

The study of glycan structure and function

Question 9

What is the benefit of branching in glycans?

Answer 9

Structural stability and ability to hold more energy

Question 10

Glycan biochemistry

Answer 10

Conjugates are identified by liquid chromatography or mass spectroscopy

Question 11

Glycan biosynthesis

Answer 11

Recruited from the environment or made within the cell in the ER or Golgi apparatus

Question 12

Glycan diversity

Answer 12

Can be found on cell surface; varies within species and across species

Question 13

Glycan recognition

Answer 13

Specific binding proteins called lectins bind to glycans to stimulate a biological response

Question 14

Lectins

Answer 14

Do not have a high affinity for glycans, so they can be disrupted by reagents for medical applications

Question 15

Oligosaccharides

Answer 15

Simple sugars that range from 3 to 20 branched and unbranched sugar residues

Question 16

What are some examples of oligosaccharides?

Answer 16

Stachyose and Raffinose

Question 17

Raffinose

Answer 17

A trisaccharide made up of 3 monomers: Galactose, glucose, and fructose

Question 18

What do plants use carbs for?

Answer 18

Energy storage and structure (cell wall)

Question 19

Cellulose

Answer 19

Made up of repeating units of a disaccharide called cellobiose; branching properties give rise to more structural integrity; make up the cell wall of plants

Question 20

Chitin

Answer 20

Linear polysaccharide that is the structural component to the exoskeletons of crustaceans and insects; also found in the tissues of animals

Question 21

Starch

Answer 21

Used by plants to store excess glucose; made up of amylose, amylopectin, and other polysaccharides

Question 22

Glycogen

Answer 22

Used by animals to store dietary sources of glucose; contains branch points

Question 23

Amylose

Answer 23

Amylose sugars form a structure where there are 6 sugars per helical turn; used by starch for energy storage

Question 24

Penicillin

Answer 24

A beta-lactamase inhibitor; Penicillin inhibits bacterial enzymes called transpeptidase through irreversible binding, causing the cell wall of bacteria to disintegrate

Question 25

How are some bacteria penicillin/antibiotic resistant?

Answer 25

Bacteria have developed two mechanisms of resistance to beta-lactam antibiotics

Question 26

Proteoglycans

Answer 26

Two types of structures: Extracellular matrix and cell surface

Question 27

Intrinsic Glycoconjugate Interactions

Answer 27

The whole cell is communicating with itself

Question 28

Extrinsic Glycoconjugate Interactions

Answer 28

Communication between the whole cell and foreign cells (ie. viruses, pathogens)

Question 29

Glycoconjugate Analysis: Liquid Chromatography

Answer 29

Peaks show the amount of each glycan species eluted over time

Question 30

Glycoconjugate Analysis: Mass Spectroscopy

Answer 30

Peaks show the molecular mass of each glycan species in the sample

Question 31

Glycoconjugate Analysis: Lectin Array

Answer 31

Use as a substrate; bind to a fluorescent "antigen"

Question 32

Glycan cleavage

Answer 32

A method of structural characterization; glycans must first be separated from the protein moiety using a cleavage reaction

Question 33

N-linked glycan

Answer 33

Removed from protein using just PNGaseF

Question 34

O-linked glycan

Answer 34

Chemicals such as NaOH and NaBH4 strip the O-linked glycan from the sugar

Question 35

What are the main functions of monosaccharides?

Answer 35

To produce and store energy

Question 36

What are the main functions of polysaccharides in living things?

Answer 36

Energy storage and structural support

Question 37

What molecules make up carbohydrates/glycans?

Answer 37

Carbon, hydrogen, oxygen

Question 38

What is the ratio of carbon, hydrogen, and oxygen in carbohydrates?

Answer 38

1:2:1 For every one carbon, there are two hydrogens and one oxygen

Question 39

What is another common name for carbohydrates?

Answer 39

Glycans

Question 40

What is the empirical formula for carbohydrates?

Answer 40

(CH2O)n, where n is greater than or equal to 3

Question 41

What are some examples of the functions of glycoconjugates?

Answer 41

1. Cell-to-cell communication 2. Cross-linkage between proteins