Carbohydrates - week 3

Question 1

What are the four most abundant elements in the universe?

Answer 1

H, He, O, C

Question 2

What are the most abundant elements in the human body?

Answer 2

Oxygen and carbon

Question 3

What are carbohydrates?

Answer 3

Molecules possessing the empirical chemical formula of (CH2O)n - hydrated carbon

Question 4

What chemical functional groups are present in aldose sugars (-CHO)

Answer 4

Aldehyde and alcohol

Question 5

What chemical functional groups are present in ketones sugars ? (-C=O)

Answer 5

Ketones and alcohol

Question 6

what is an example of an important human carbohydrate?

Answer 6

Glucose

Question 7

What is the bulk carb ingested?

Answer 7

Starch - a polymer of glucose eg. In bread, potatoes pasta, rice

Question 8

What other carbs are present in the body ?

Answer 8

• Ribose, deoxyribose in RNA and DNA
• Lactose in milk
• Glycogen stored in liver and muscles

Question 9

What is the sole fuel molecule in the brain and red blood cells?

Answer 9

Glucose

Question 10

What diseases are associated with abnormal carb metabolism?

Answer 10

• diabetes
• galactosaemia
• fructose intolerance
• lactose intolerance

Question 11

How to classify a carb?

Answer 11

• monosaccharides
• disaccharides
• oligosaccharides
• polysaccharides

Question 12

What are monosaccharides?

Answer 12

Basic unit of carbs that cannot be broken down into simpler sugars

Question 13

name 4 monosaccharides

Answer 13

Glucose
Fructose
Galactose
Ribose

Question 14

What are disaccharides?

Answer 14

Composed of two monosaccharide sugar units, which may be the same or two different monosaccharides

Question 15

Name three examples of disaccharides

Answer 15

Maltose
Sucrose
Lactose

Question 16

What is maltose made up of?

Answer 16

Glucose + glucose

Question 17

What is sucrose made up of?

Answer 17

Glucose + fructose

Question 18

What is lactose made up of?

Answer 18

Glucose + galactose

Question 19

What are oligosaccharides?

Answer 19

Defined as containing between 3 and 10 monosaccharide units, which may be the same or a mixture of different monosaccharides

Question 20

What are polysaccharides?

Answer 20

• high molecular wight carbohydrate polymers defined as containing 11 or more monosaccharide units

Question 21

How many monosaccharide units do important biological polysaccharides contain?

Answer 21

Many hundreds

Question 22

How can a polysaccharide be structured?

Answer 22

May be linear or branched

Question 23

Give an example of a linear polysaccharide

Answer 23

Cellulose

Question 24

Give an example of a branched polysaccharide

Answer 24

Glycogen, starch

Question 25

What are homopolysaccharides?

Answer 25

Contain only one type of monosaccharide unit

Question 26

Give an example of a homopolysaccharide

Answer 26

Cellulose, glycogen, starch

Question 27

What are heteropolysaccharides?

Answer 27

Contain two or more different types of monosaccharide unit

Question 28

Give an example of heteropolysaccharides

Answer 28

Heperin, mucins, glycoproteins, hyaluronic acid

Question 29

Simple monosaccharides are polyhydroxy aldehydes and ketones that react chemically as both..

Answer 29

alcohols and either aldehydes or ketones

Question 30

What are the most common additional chemical functional groups some more complex monosaccharides have?

Answer 30

carboxylic acid and mint groups

Question 31

What is the minimum number of carbon atoms in a monosaccharide sugar?

Answer 31

3 and no limit

Question 32

How do you call monosaccharides with 3,4,5,6 carbons respectively?

Answer 32

trios tetrose pentose hexose

Question 33

Where are all aldose sugars derived from?

Answer 33

- D or L form of glyceraldehyde - addition of extra HCOH group - retaining aldehyde CHO group at top - retaining hydroxymethyl group (CH2OH) at bottom

Question 34

In human metabolism, what series do you encounter? D or L

Answer 34

D

Question 35

What is the general rule for calculating the number if isomers for monosaccharides containing a defined nr of carbon atoms?

Answer 35

determine the number of asymmetric carbons eg. N the nr of isomers will be 2^N

Question 36

Example: calculate the number of isomers of glucose

Answer 36

6 carbon atoms, 4 asymmetric centres :. 2^4= 16

Question 37

What are enantiomers?

Answer 37

Mirror images

Question 38

What are diasterioisomers?

Answer 38

not mirror images

Question 39

What are epimers?

Answer 39

differ at 1 position

Question 40

is glucose water soluble?

Answer 40

Yes

Question 41

Can glucose contain an amino group?

Answer 41

yes, usually on C2 - glucosamine

Question 42

What happens if in glucose a hydroxyl is replaced by an H ?

Answer 42

it creates deoxysgars eg. fructose, 6 deoxygalactose, deoxyribose 5C

Question 44

Describe glucose attributes?

Answer 44

- contains -OH groups - reacts as alcohols giving organic esters with acids and phosphates ad sulphates with phosphoric and sulphuric acid respectively - contains an aldehyde group which can be either oxidised or reduced

Question 45

How much alpha D glucopyranose is there?

Answer 45

around 36%

Question 46

How much beta D glucopyranose is there?

Answer 46

around 64%

Question 47

How much D glucose (open chain form) is there>

Answer 47

less than 1%

Question 48

Are pyranose and furganose rings planar?

Answer 48

no - chain form, boat form

Question 49

What bond forms in reactions with alcohols eg methanol?

Answer 49

O glycosidic bonds

Question 50

What bonds forms interactions with amines to form glucosamines?

Answer 50

N glycosidic bonds

Question 51

Which of the two, glucose or glucosamine can be readily oxidised?

Answer 51

glucose

Question 52

What is glucosamine?

Answer 52

a nonreducing sugar

Question 53

What does the diabetes mellitus test do?

Answer 53

measures glycosylated haemoglobin as glucose binds to haemoglobin

Question 54

What can be functions of sugars?

Answer 54

antibodies cellular communications neurotransmission chitin in cancer cells cell surfaces

Question 55

Describe phosphorylated sugars

Answer 55

- key intermediates in energy generation and biosynthesis - can not cross the membrane because of the negative charge phosphorylation makes them more reactive in important metabolic pathways