Carbohydrates - week 3 Flashcards

1
Q

What are the four most abundant elements in the universe?

A

H, He, O, C

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2
Q

What are the most abundant elements in the human body?

A

Oxygen and carbon

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3
Q

What are carbohydrates?

A

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

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4
Q

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

A

Aldehyde and alcohol

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5
Q

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

A

Ketones and alcohol

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6
Q

what is an example of an important human carbohydrate?

A

Glucose

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7
Q

What is the bulk carb ingested?

A

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

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8
Q

What other carbs are present in the body ?

A
  • Ribose, deoxyribose in RNA and DNA
  • Lactose in milk
  • Glycogen stored in liver and muscles
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9
Q

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

A

Glucose

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10
Q

What diseases are associated with abnormal carb metabolism?

A
  • diabetes
  • galactosaemia
  • fructose intolerance
  • lactose intolerance
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11
Q

How to classify a carb?

A
  • monosaccharides
  • disaccharides
  • oligosaccharides
  • polysaccharides
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12
Q

What are monosaccharides?

A

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

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13
Q

name 4 monosaccharides

A

Glucose
Fructose
Galactose
Ribose

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14
Q

What are disaccharides?

A

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

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15
Q

Name three examples of disaccharides

A

Maltose
Sucrose
Lactose

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16
Q

What is maltose made up of?

A

Glucose + glucose

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17
Q

What is sucrose made up of?

A

Glucose + fructose

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18
Q

What is lactose made up of?

A

Glucose + galactose

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19
Q

What are oligosaccharides?

A

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

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20
Q

What are polysaccharides?

A
  • high molecular wight carbohydrate polymers defined as containing 11 or more monosaccharide units
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21
Q

How many monosaccharide units do important biological polysaccharides contain?

A

Many hundreds

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22
Q

How can a polysaccharide be structured?

A

May be linear or branched

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23
Q

Give an example of a linear polysaccharide

A

Cellulose

24
Q

Give an example of a branched polysaccharide

A

Glycogen, starch

25
Q

What are homopolysaccharides?

A

Contain only one type of monosaccharide unit

26
Q

Give an example of a homopolysaccharide

A

Cellulose, glycogen, starch

27
Q

What are heteropolysaccharides?

A

Contain two or more different types of monosaccharide unit

28
Q

Give an example of heteropolysaccharides

A

Heperin, mucins, glycoproteins, hyaluronic acid

29
Q

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

A

alcohols and either aldehydes or ketones

30
Q

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

A

carboxylic acid and mint groups

31
Q

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

A

3 and no limit

32
Q

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

A

trios
tetrose
pentose
hexose

33
Q

Where are all aldose sugars derived from?

A
  • D or L form of glyceraldehyde
  • addition of extra HCOH group
  • retaining aldehyde CHO group at top
  • retaining hydroxymethyl group (CH2OH) at bottom
34
Q

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

A

D

35
Q

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

A

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

36
Q

Example: calculate the number of isomers of glucose

A

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

37
Q

What are enantiomers?

A

Mirror images

38
Q

What are diasterioisomers?

A

not mirror images

39
Q

What are epimers?

A

differ at 1 position

40
Q

is glucose water soluble?

A

Yes

41
Q

Can glucose contain an amino group?

A

yes, usually on C2 - glucosamine

42
Q

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

A

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

43
Q
A
44
Q

Describe glucose attributes?

A
  • 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
45
Q

How much alpha D glucopyranose is there?

A

around 36%

46
Q

How much beta D glucopyranose is there?

A

around 64%

47
Q

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

A

less than 1%

48
Q

Are pyranose and furganose rings planar?

A

no - chain form, boat form

49
Q

What bond forms in reactions with alcohols eg methanol?

A

O glycosidic bonds

50
Q

What bonds forms interactions with amines to form glucosamines?

A

N glycosidic bonds

51
Q

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

A

glucose

52
Q

What is glucosamine?

A

a nonreducing sugar

53
Q

What does the diabetes mellitus test do?

A

measures glycosylated haemoglobin as glucose binds to haemoglobin

54
Q

What can be functions of sugars?

A

antibodies
cellular communications
neurotransmission
chitin
in cancer cells
cell surfaces

55
Q

Describe phosphorylated sugars

A
  • 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
56
Q
A