BioChem Of Carbohydrates

Question 1

Biological importance of carbohydrates

Answer 1

• source and storage of energy
• molecular tag
• backbone of other macromolecules ( DNA )
• structural components ( cellulose )
• some derivates make drugs ( cardiac glycosides )

Question 2

Criteria for Classification of monosaccharides

Answer 2

Based on
1 number of c-atoms in chain
2 function group ( aldehyde or ketone )

Question 3

Chemical name of glucose and why

Answer 3

-polyhydroxy aldehyde as it has an aldehyde and several hydroxy groups

Question 4

Number of c-atoms and name ( from 3 )

Answer 4

3 triose
4 tetrase
5 pentase
6 hexase

Question 5

Stereoisomers of carbohydrates

Answer 5

-can form optical isomers

Question 6

How are optical isomers formed and prerequisite for a compound to form it

Answer 6

-diff In directon of rotation of polarized light

-must have a chiral center
c-atom bonded to 4 diff atoms or group of atoms

Question 7

Characteristics of stereoisomers

Answer 7

-the two isomers are mirror images of each other and cannot be superimposed

Question 8

Name of isomers based on direction of rotation of light

Answer 8

• detrorotators ( D ) to the right

- leverotatory ( L ) to the left

Question 9

How do we designate stereoisomers to carbohydrates

Answer 9

-use penultimate chiral carbon

furthest chiral center from carbonyl group

Question 10

Types of monosaccharides rings and how are they formed

Answer 10

1 pyranose ring ( C1 binds to OH of C5 ) eg glucose

2 furanose ( C1 binds to OH of C4 ) eg ribose

Question 11

Types of carbohydrates based on number of units

Answer 11

1 mono
2 Di
3 oglio ( 2-10 )
4 poly ( >10 )

Question 12

What is a hemiacetal and hemiketal and position of anomers

Answer 12

-product formed when adding alcohol to carbonyl

• aldehyde ( aldoses ) C1
• ketone ( ketoses ) C2

Question 13

Alpha and beta designations on rings and what is anomeric

Answer 13

• position of OH on anomeric carbon
• alpha below ring
• beta above

-c-atom on carbonyl group

Question 14

What are anomers

Answer 14

-stereoisomers of sugars which differ only on arrangement of atoms or atom on carbonyl c-atom

Question 15

Mutarotation

Answer 15

-reaction which interchanges anomers to each other’s forms

Question 16

Important monosaccharides

Answer 16

1 ribose - backbone of RNA
2 deoxyribose - backbone of DNA
3 galactose - incorporated with glucose to lactose( milk sugar )
4 glucose - ( blood sugar / dextrose ) metabolism in body to produce energy
5 fructose - ( fruit sugar / levulose ) present in plants for energy release the one metabolized

Question 17

Stereoisomers found naturally in nature of carbohydrates

Answer 17

D

Question 18

Derivatives of monosaccharides and product formed

Answer 18

1 amino sugars - OH replaced by NH2 eg in glucose it gives glucosamine

2 sugar acids - oxidation of alcohol or aldehyde to give carboxylic acid

• oxidation of C1 : aldonic acid
• oxidation of C6 : alduronic acid
• oxidation of C1 + C6 : aldaric acid

Question 19

Modifications of amino sugars

Answer 19

Can be sulfated or acetylated to form

N- acetyl or N-sulfate groups

Question 20

Glycosidic bond formation

Answer 20

-elimination of water between anomeric group of one sugar and OH of another sugar

Question 21

Two types of glycosidic bonds

Answer 21

1 O-glycoside : bond between 2 monosaccharides

2 N-glycoside : between anomeric group and amine of another ( nucleoside )

Question 22

What is a disaccharide

Answer 22

-compound formed between 2 monosaccharides via a glycosidic bond

Question 23

Important disaccharides and monosaccharide a-b designation and function

Answer 23

1 sucrose : glucose(a) + fructose(b) / a(1-4) bond { plant sugar

2 lactose : galactose(b) + glucose(a) / b(1-4) bold { milk sugar

3 maltose : glucose + glucose / a(1-4) bond { intermediate product during starch breakdown

4 cellebiose : glucose(b) + glucose(b) / b(1-4) bond { intermediate during cellulose breakdown

Question 24

What is a polysaccharides

Answer 24

-carbohydrate compound with >10 units in the polymer

Question 25

Important polysaccharides, structure ( subunits ) and function

Answer 25

1 starch - storage of sugar in plants a(1-4) glucose

2 cellulose - cell wall of plant cells b(1-4) glucose

3 glycasoaminoglycans - polymers of repeating disaccharides
Made of modified sugars - amino sugar and uronic acid

4 heparin - anticoagulant gag

5 proteoglycans- core protein attached to sulfates gag’s. Trap water in ecm of CT

6 glycoprotein - polysaccharide chain attached to extra cellular side of lemma

• aggregates platelets
• interaction with cells
• ABO blood typing

Question 26

Two types of starch, structure, characteristics and function

Answer 26

1 amylose - long unbranded chain of glucose a(1-4)

• 10-20% in plants
• can form coils which trap iodine giving deep blue-purple color

2 amylopectin - long a(1-4) glucose chain but with a(1-6) branches every 30th residue

Question 27

Glycogen structure and function

Answer 27

Similar to amylopectin but with more branches at more regular intervals ( every 12th residue )

Question 28

Use of branches on glycogen and function of glycogen

Answer 28

• make a more compact structure and multiple chain ends for enzymes allowing for quicker release of energy
• storage form of animals

Question 29

Orientation of polysaccharide chain

Answer 29

• has a tandem of upright and flipped monosaccharides due to orientation of glucosidic bond
• provide strong rigid bundles that pack into microfibrils

Question 30

How do gag’s store water

Answer 30

• highly negative charge due to acidic groups

- polar so can bind to water

Question 31

What is ABO blood typing and the types and how to make them

Answer 31

• use of glycoprotein ogliosaccharides chains on surface of RBC to categorize blood
• every human can make O
• add galactose to O and we have B
• add n-acetylgalactosamine to O and we have A