Carbs 2

Question 1

what can the hydroxyl groups of carbohydrates be converted into ?

Answer 1

they can be converted to esters or ethers. Also can be oxidized

Question 2

what can the carbonyl groups be converted to and what can they react with ?

Answer 2

they can be oxidised or reduced and react with nucleophiles.

Question 3

in a cyclic sugar what carbon is the most react and why ?

Answer 3

the anomeric carbon ( C1) as it has 2 c-0 bonds whereas all the others have one c-0 bond. The 2 oxygens have a withdrawing effect on the electrons so they become slighty negative while the C become slightly positive and as a result is prone to nucleophilic attack.

Question 4

what is the cyclic form of monosaccharides ?

Answer 4

hemiacetals

Question 5

what can the hemiacetals react with and what does this produce ?

Answer 5

react with alcohol and acids to form an acetal at the anomeric carbon.

Question 6

what are these monosachharide acetals called ?

Answer 6

glycosides

Question 7

what are glucose acetals called ?

Answer 7

glycosides

Question 8

monnose acetal ?

Answer 8

mannosides

Question 9

fructose acetals ?

Answer 9

fuctosides

Question 10

what is produced when D glucose reacts with methanol and hydrochloric acid ?

Answer 10

methyl alpha - D- pyranoglucoside and methyl beta - D - glucopyranoside

Question 11

do glycosides undergo hydrolysis with water and base ?

Answer 11

nope

Question 12

what is required for a glycoside to undergo hydrolysis and what is produced ?

Answer 12

acid , it forms a hemiacetal sugar and alcohol ( aglycone) due to the presence of the 2 oxygens at the anomeric carbon

Question 13

what will a reducing sugar contain and what do they react with ?

Answer 13

an OH group at the anomeric carbon react with oxidising agents such as 
hydrogen peroxide 
bromine water 
benedicts solution
tollens reagent

Question 14

what occurs to the sugar and the reagent ?

Answer 14

the sugar is oxidised to an aldonic acid while the reagents are reduced . This is a redox reaction

Question 15

what is tollen’s reagent ?

Answer 15

Oxidising agent. this is a solution of silver nitrate and ammonia , it is reduced to form a silver mirror

Question 16

What is benedict’s solution ?

Answer 16

Oxidising agent. this is an aqueous solution containing copper ions. It is reduced to give a brick red percipitate as copper oxide is formed

Question 17

what does a positive test to a benedict’s solution tell you ?

Answer 17

that the sugar is a reducing agent , this will have a hemiacetal group which is in equilibrium with the open chair form ( ketone or aldehyde)

Question 18

what does it tell you if a sugar doest react with the chemical oxidising agents ?

Answer 18

then it is a non reducing sugar that has an acetal at the anomeric carbon ( glycoside)

Question 19

what does the oxidation of the primary alcohol group in a aldose produce ?

Answer 19

a - uronic acid

Question 20

what are oligosaccarides associated with ?

Answer 20

proteins (glycoproteins) and lipids ( glycolipids)

Question 21

what’s the most common oligosachharide ?

Answer 21

disaccharide , 2 component monosaccaride

Question 22

what forms between 2 sugars ?

Answer 22

a glycosidic link between the C1 and any hydroxyl group on the second sugar.

Question 23

what occurs if the glycosidic link is different each time ?

Answer 23

then different proteins and DNA will be produced

Question 24

what is starch hydrolysed to produced and what is needed for this to occur ?

Answer 24

Produces maltose and enzyme diastase is needed.

Question 25

what does partial hydrolysis of cellulose produce ?

Answer 25

cellobiose which is an isomer of maltose

Question 26

what is maltose and cellobiose composed of ?

Answer 26

2 glucose units linked by a 1 - 4 glycosidic link

Question 27

what anomer of glucose is maltose ?

Answer 27

A anomer

Question 28

what anomer of glucose is cellobiose ?

Answer 28

b anomer

Question 29

what determines if the oligosaccaride is digestable ?

Answer 29

the position of the glycosidic link , whether its an a or b anomer

Question 30

what is lactose composed of ?

Answer 30

two different monosaccarides , D - glucose and D - galactose

Question 31

whats the difference between glucose and galactose ?

Answer 31

They are epimers and only differ in orientation of hydroxyl at C-4.

Question 32

why are some people lactose intolerant ?

Answer 32

they lack the enzyme lactase ( galactosidase) to hydrolyse the glycosidic bond between the 2 monnosaccarides

Question 33

what is sucrose ?

Answer 33

the most abundant natural type of disaccharide

Question 34

is sucrose a reducing sugar and does it undergo mutarotation ?

Answer 34

not a reducing sugar and no

Question 35

what does sucrose produce when hydrolysed ?

Answer 35

Mixture of glucose and fructose called invert sugars

Question 36

what enzymes catalyses the hydrolyses of sucrose ?

Answer 36

B -D- fructofuranoside

Question 37

what can polysaccarides also be called ?

Answer 37

glycans

Question 38

what are heteropolysaccarides composed of ?

Answer 38

more than one type of monosaccaride unit

Question 39

what are homopolysaccarides composed of ?

Answer 39

one type of monosaccride unit

Question 40

what are glucose homopolysaccarides called ?

Answer 40

glucans

Question 41

what are galactose homopolysaccarides called ?

Answer 41

galactans

Question 42

describe the primary structuure of polysacarides ?

Answer 42

this is the monomer building blocks

Question 43

give an example of a primary structure , linear polysaccaride.

Answer 43

cellulose

Question 44

can we digest cellulose and what is it composed of ?

Answer 44

nope composed of glucose molecules joines by a 1 - 4 glycosidic link

Question 45

what is cellulase required for ?

Answer 45

its an enzyme that is required to hydrolyse the glycosidic bonds between the glucose molecules in cellulose

Question 46

where are these enzymes normally found ?

Answer 46

in the digestive tract

Question 47

whats the 2 groups that starch can be divided into ?

Answer 47

amylose and amylopectin

Question 48

describe amylose

Answer 48

insoluble in cold water

Question 49

describe amylopectin

Answer 49

soluble in cold water

Question 50

when starch is eaten what is it hydrolysed by ?

Answer 50

an enzyme called glycosidase

Question 51

what glycosidic link does glycosidases hydrolyse ?

Answer 51

A not b

Question 52

why is D glucose stored as a polymer than monomer units ?

Answer 52

to avoid large osmotic pressure

Question 53

what would occur in plants if glucose was stored in monomeric units rather then polymer ?

Answer 53

the membrane would rupture due to large osmotic pressure

Question 54

describe the structure of amylopectin ?

Answer 54

it is a glucan polymer

Question 55

what is glycogen a polysaccaride of ?

Answer 55

glucose

Question 56

whats is more heavily brachned , glycogen or amylopectin ?

Answer 56

glycogen

Question 57

what has high glycogen stores and why ?

Answer 57

skeletal muscles and the liver so that this allows quick release of energy

Question 58

what is needed to convert glycogen to glucose ?

Answer 58

glycogen phosphorylase

Question 59

where does glycogen phorphorolase work and what occurs ?

Answer 59

at the non reducing end of the glycogen unit and it works one glucose molecule at a time

Question 60

whats the limit to how glycogen phosphorlayse works ?

Answer 60

it cannot cleave glycosidic linkages that are closer than 4 glucose unit from a branch

Question 61

what is 75% of the carbohydrtaes consumed by ?

Answer 61

the brain as glucose

Question 62

what is most of the carbohydrates intake in the form of ?

Answer 62

starch with some glycogen

Question 63

can the body use starch and glycogen directly ?

Answer 63

nope must be broken down to glucose

Question 64

what is the secondary structure detail ?

Answer 64

the way the backbone is folded to give 3D shape

Question 65

what does secondary structure result from ?

Answer 65

the local conformational variety , which is due to rotations around the bonds involved in glycosidic linkages

Question 66

what does the favourable bond rotation around a link produce ?

Answer 66

helix

Question 67

what does the favourable bond rotations around b link form ?

Answer 67

zig zag

Question 68

what is an arrangement associated with cellulose ?

Answer 68

ribbons

Question 69

what is tertiary structure concerned with ?

Answer 69

the way the polysaccaride backbone is arranged in 3D space.

Question 70

what is quaternanry polysaccaride structure associated with ?

Answer 70

The way the polysaccaride interacts with other chains

Question 71

what is the chain packing and folded dictated by ?

Answer 71

the non covalent , long range interactions between the functional groups present on the monosacaride units

Question 72

explain what makes up a ribbon structure ?

Answer 72

this is when the b linked glucose units ( cellulose) or units in chitin are described as b linked ribbons. In both molecules there is a uniform distribution of hyroxyl groups on the outside of each chain. , so when 2 or more cellulose or chitin chains make contact the OH groups are ideally arranged to make hydrogen bonds

Question 73

what is the roatation of each glucose unit in cellulose at ?

Answer 73

180 relative to the next glucose unit

Question 74

what is the resulting ribbon stabilised by ?

Answer 74

intramolecular hydrogen bonds between OH groups on adjacent glucose units

Question 75

where is cellulose found and is it soluble in water ?

Answer 75

Found in cells walls and it is insoluble in water

Question 76

what type of glycosidic bonds do amylose and amylopectin have and what does this result in ?

Answer 76

they have a glycosidic bonds and as a resuly the chains have a wide hollow helix that is stabilised by hydrogen bonds

Question 77

if small molecules are accomidated into the central cavities of the helix what forms ?

Answer 77

An inclusion complex

Question 78

what does the iodine starch tests result in the blue - violet colour ?

Answer 78

because the aqueous solution of the iodine and ions forms an inclusion complex with the starch. The tri iodide anions fit in the middle of the cavity

Question 79

when are buckled ribbons formed ?

Answer 79

this is when the polysaccaride chain packs but leaves a cavity

Question 80

what can these cavities be filled with and how is this beneficial ?

Answer 80

can be filled with water or metal ions to give extra stability to the polysaccharide

Question 81

give an example of an acid that forms a buckled ribbon

Answer 81

pectic acid

Question 82

what are cyclodextrins ?

Answer 82

this is when there is natural occurring macrocycles composed of sugar units

Question 83

how are cyclodextrins obtained ?

Answer 83

due to the enzymatic degradation of starch

Question 84

whats the interior and exterior of cyclodextrins?

Answer 84

the inside is hydrophobic but outside is hydrophyllic

Question 85

what is the interior ideal for ?

Answer 85

apolar guests such as drug molecules

Question 86

whats the exterior being hydrophilic mean ?

Answer 86

that any molecule that complexes with the cyclodextrin is soluble in water which means the drug can be transported to their receptors

Question 87

what is rocuronium ?

Answer 87

this is a muscle relaxant used as part of the anaesthesia during surgery

Question 88

what is used to reverse the action of rocuronium and what is it ?

Answer 88

sugammadex which is a a cyclodextrin

Question 89

how does sugammedex work ?

Answer 89

it binds the rocoronium within its hydrophobic inteiror