Chapter 11 - Carbohydrates

Front 1

What is the generic formula of a carbohydrate?

Back 1

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

Front 2

What are carbohydrates formed from?

Back 2

CO2 and H2O

Front 3

What are the roles of carbohydrates?

Back 3

Energy in diet

Mediating intercellular communication

Structural support (e.g. cell walls)

Front 4

How are carbohydrates classified?

Back 4

By length

Front 5

What are monosaccharides?

Back 5

Simple sugars

Front 6

What are the different types of small polymers of sugars?

Back 6

Disaccharides = two sugars bound together

Trisaccharides = three sugars bound together

Oligosaccharides = "several" sugars bound together

Front 7

What are large polymers of sugars?

Back 7

Polysaccharides

Front 8

What has five carbons?

Back 8

Pentose

Front 9

What are six carbons?

Back 9

Hexose

Front 10

What is the simplest aldose?

Back 10

Glyceraldehyde

Front 11

What are the characteristics of monosaccharides?

Back 11

Described based on the number of carbon atoms in the molecules

Made from aldehydes to form aldoses

Made from ketones to form ketoses

Front 12

What is the simplest ketose?

Back 12

Dihydroxyacetone

Front 13

T or F: Most carbohydrates are chiral

Back 13

True

Front 14

What is the definition of chiral?

Back 14

Have at least one chiral carbon = bound to four different groups

Front 15

What does L stand for?

Back 15

Levorotatory

Front 16

What does D stand for?

Back 16

Dextrorotatory

Front 17

How do enantiomers behave?

Back 17

Although enantiomers behave identically in a strictly chemical sense, they are NOT biologically equivalent

Front 18

How can biological systems be distinguished?

Back 18

As L or D

Front 19

What are the rules for L and D notation?

Back 19

Draw aldehyde or ketone group at the top

Identify lowest chiral center in the molecule

Classify configuration based on OH group

Front 20

How do you distinguish L and D notation?

Back 20

If OH is on the right = D

If OH is on the left = L

Front 21

What configuration do most sugars in nature have?

Back 21

D notation

Front 22

What are epimers?

Back 22

Sugars that differ only by the configuration around one carbon atom

Front 23

T or F: The same sugar can only be represented in one way

Back 23

False

Front 24

Describe the cyclization of glucose

Back 24

Since the aldehyde group has rotational freedom about the C1 - C2 bond, anomers are possible

Alpha-D-Glucose is most prevelant in biochemistry

Front 25

In what two ways can carbohydrates be drawn?

Back 25

Haworth projections

Fischer projections

Front 26

What links the anomeric carbon with another group?

Back 26

Glycosidic bonds

Front 27

Are cyclical sugars nonplanar?

Back 27

Yes

Front 28

T or F: Monosaccharides can be derivatized in many different ways

Back 28

True

Front 29

What is a key distinction between DNA and RNA?

Back 29

The 2'OH group is only found in RNA

Front 30

What does the enzyme ribonucleotide reductase catalyze?

Back 30

The removal of the 2'OH group

Front 31

What is a popular sugar that is used as a sweetener in chewing gum, and has been shown to help prevent cavities?

Back 31

Xylitol

Front 32

What is milk sugar?

Back 32

Lactose

Front 33

What are the characteristics of the structure of lactose?

Back 33

Lactose has a beta(1-->4) glycosidic bond

Front 34

What is the most abundant sugar in nature?

Back 34

Sucrose

Front 35

Describe the structure of sucrose

Back 35

Has an alpha(1-->2) glycosidic bond

Front 36

What is cellulose composed of?

Back 36

Glucose in beta(1-->4) linkages

Front 37

What is formed by cellulose?

Back 37

Extended fibers that lend strength and rigidity to plant cell walls due to beta(1-->4) linkage

Front 38

What two types of polymers is starch composed of?

Back 38

1. Amylose

2. Amylopectin

Front 39

What is amylose?

Back 39

A linear and helical polymer of glucose with an alpha(1-->4) glycosidic bonds

Front 40

What is amylopectin?

Back 40

A branched polymer of glucose with a beta(1-->6) glycosidic bonds

Front 41

Describe starch (plants) and glucose (animals) functions

Back 41

Glucose polymers that store energy

Glucose polymers are linked by alpha(1-->4) glycosidic bonds

Front 42

What are the characteristics of glycogen?

Back 42

Found in animals, not plants

Similar to amylopectin, but has a higher degree of branching

Glucose is needed by the body --> quick removal of glucose monomers form multiple branch ends simultaneously

Straight chains like amylose provide only one glucose molecule at a time --> slower to provide energy

Front 43

What happens when bacteria polysaccharides form a biofilm?

Back 43

Bacteria produce extracellular polysaccharides that forma biofilm

Front 44

What is a biofilm?

Back 44

A protective covering for bacteria to grow and thrive