Carbohydrates

Question 1

What are trioses?

Answer 1

simplest monosaccharides

Question 2

Monosaccharides:

Answer 2

(CH2O)n n=3

Question 3

Define chiral and achiral:

Answer 3

chiral

• not identical to its reflection
• cannot be superimposed
• i.e hands

achiral

• identical to its reflection
• can be superimposed

Question 4

What are the two classes of monosaccharides?

Answer 4

-Aldose (=o) at end of chain
[D-Glyceraldehyde]

-Ketose (=o) not at the end
[Dihydroxyacetone]

Question 5

Chirality of Saccharides:

Answer 5

-Almost all monosaccharides in nature are “D enantiomers” just as almost all amino acids are “L enantiomers”

Question 6

Terminology of Saccharides:

Answer 6

triose 3
tetrose 4
Pentose 5
hexose 6
"Aldo, Keto + -"

Question 7

Modification of sugars:

Answer 7

Hydroxyl (OH-) groups replaced by amine (NH2) to result in sugar -“amines”

Question 8

Oxidation of Aldoses:

Answer 8

-Aldoses can be oxidized into aldonic acids
-Aldehyde group is replaced by carboxylic group
-Aldoses are called reducing sugars
i.e (D-Glucose into D-Gluconate)
[] Ketoses are non-reducing sugars cannot go through this reaction

Question 9

Reactivity of reducing and non-reducing sugars:

Answer 9

Non-reducing sugars lasts long doesn’t react so readily

Reducing sugars doesn’t last long

Question 10

What are polysaccharides made out of?

Answer 10

Monosaccharides joined together by glycosidic linkages/bonds

Question 11

Lactose is made from…?

Answer 11

Glucose+Galactose

Question 12

Structural roles of Polysaccharides, Describe the Cellulose structure:

Answer 12

Sheets of cellulose stacked and stabilized by hydrogen bonds and van der waals interactions

Because of this “stacking feature” which there are many bonds between stacks, cellulose is very stable and difficult to break apart

Question 13

Benefits of cellulose’s stacking feature:

Answer 13

Stability of cellulose provides tremendous strength and allows trees to grow to massive scales

Question 14

Cons of cellulose’s stacking feature:

Answer 14

This same stability makes it difficult to breakdown cellulose into glucose units for biofuels

Question 15

What is a major component in inverterbrates?

Answer 15

Chitin- exoskeletons, similar to cellulose where it provides great strength for protection

Question 16

Polysaccharide as energy store: Amylose and Amylopectin

Answer 16

Amylose is organized in ribbon shapes and easily broken because there are fewer bonds within the ribbon

Question 17

Differences between Amylose and Cellulose:

Answer 17

Amylose:
held by alpha glycosidic bonds easily broken down

Cellulose:
held by beta glycosidic bonds, strong surface

Question 18

Protein + Carbohydrate=

Answer 18

-proteins made according to their RNA sequences
Carbohydrate-added by enzymes to the proteins after they are fully synthesized

Glycoprotein

Question 19

What is Eukaryotic Glycosylation?

Answer 19

In Eukaryotic cells, nearly all secreted and membrane proteins are glycosylated or have added sugars

Question 20

Protein Glycosylation: What is N-glycosylation and O-glycosylation?

Answer 20

N glycosylation is the attachment of oligosaccharide sugar molecule to a nitrogen atom in the asparagine residue of a protein molecule

O glycosylation is the attachment of a sugar molecule to the oxygen atom of serine or threonine side chain residues in a protein molecule

Question 21

Glycosylation means…

Answer 21

simply attaching sugar to something

-the saccharide component of proteins have important functions, such as antibody recognition of blood types

Question 22

Give an example of an application using glycosylation:

Answer 22

The H, A and B antigens are located on the surface of our cells

• Only H-> O blood type
• Only A or B -> A or B
• A and B-> AB