Topic 7

Question 1

Carbohydrates

Answer 1

• important source of energy
• used for cell-cell recognition
• a coating to protect cells/ entire organisms

Question 2

Simplest Carbohydrates

Answer 2

• monosaccharides

Question 3

Monosaccharides

Answer 3

• units that can be joined together to form larger and more complex carbohydrates (polysaccharides)
• General Formula: (CH2O)n
  -n: usually a number between 3-7

Question 4

Glyceraldehyde

Answer 4

• Simple example of a monosaccharide
• One carbon is double bonded to an oxygen atom (carbonyl group)
• each other carbon isbonded to an OH group (an alcohol group)

Question 5

An Aldose

Answer 5

• ex . glyceraldehyde
• Carbonyl group is attatched to a terminal carbon
• double bonded to an analdehyde group

Question 6

A Ketose

Answer 6

• carbonyl group is attatched to a center carbon (a ketone group)

Question 7

Chiral Carbon

Answer 7

• carbons with 4 different chemical groups bonded to them

Question 8

Enantiomers

Answer 8

• mirror images of eachother
• same chemical groups
• They cannot be superimposed on eachother (distinct molecules)

Question 9

Hexoses

Answer 9

• contains 6 carbons
• They are all isomers of eachother (same chemical formula)

Question 10

To Number the Carbons

Answer 10

• start with the carbon closest to the carbonyl group

Question 11

D-sugar

Answer 11

• if the OH group on the highest chiral carbon is on the right

Question 12

Epimers

Answer 12

• monosaccharides that are isomers + differ only by the steveochemistry
  around one carbon

Question 13

Cyclization

Answer 13

• Anomeric carbon is attched to a oxygen

Question 14

Haworth Projections

Answer 14

• OH group on carbon 1 can be up or down - both equally legitiamite
• If OH group is on the right of a fischer projection: will be down in Haworth
• If OH group is on the left of a fischer projection: Will be up in Haworth

Question 15

Anomeric Carbon

Answer 15

• a configurations possible upon cyclization
• always has 2 bonds to oxygen

Question 16

Alpha Glucose

Answer 16

• the OH group of carbon atom 1 is on the opposite side of carbon 6 substituent

Question 17

Beta Glucose

Answer 17

• the OH group of carbon atom 1 is on the same side of carbon 6 substituent

Question 18

Disaccharides

Answer 18

• monosaccharides can be joined in a condensation reaction

Question 19

Sugar

Answer 19

• sucrose (common usage)

Question 20

Polysaccharides as Energy Storage

Answer 20

1. Glycogen in Animals
2. Starch in Plants

Question 21

1. Glycogen in Animals

Answer 21

• 12-14 glucoses
• alpha (1-4) linkages
  carbon 1 of one atom and carbon 4 of another are in alpha positions

Question 22

2. Starch in Plants

Answer 22

• 1. amylose
• 2. amylopectin

Question 23

Amylose

Answer 23

• 20-30%
• alpha (1-4)- polyglucose
• very few branch points

Question 24

Amylopectin

Answer 24

-70-80%
- alpha (1-4)- polyglucose
- alpha (1-6) branches every 24-30 glucose monomers

Question 25

Humans

Answer 25

- can easily digest glycogen and starch

Question 26

Cellulose

Answer 26

- unbranched beta(1-4) polyglucose - humans cannot digest beta

Question 27

Pectin

Answer 27

- unbranched alpha(1-4) polymer - mainly D-galacturonic acid - partially methylates

Question 28

Dietary Fibre

Answer 28

- polysaccharides that humans digest poorly

Question 29

Oligosaccharides as Cell Coating

Answer 29

- protect cells - make cells slippery - mediate cell-cell recognition