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Biochemistry > Monosaccharides and their Properties > Flashcards

Monosaccharides and their Properties Flashcards

1
Q

Define monosaccharides

A

the simplest form of carbs that can’t be further hydrolyzed into sugars

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2
Q

Monosaccharides are colorless, ______ solids that are _______ in water, but insoluble in _______ solvents. Most have a _____ taste.

A

crystalline
very soluble
nonpolar
sweet

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3
Q

What is the backbone of common monosaccharides?

A

unbranched carbon chains

-all the carbons are linked by single bonds

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3
Q

What is the backbone of common monosaccharides?

A

unbranched carbon chains in which all the carbons are linked by single bonds

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4
Q

The carbon atoms are given numbers starting from _________. In glucose, the first carbon is the __________ group.

A

the first carbon

aldehydic group

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5
Q

Nomenclature ; According to the presence of an aldehyde or ketone group:
-Ose means:

A

aldose (containing an aldehyde group)
ketose (containing a ketone group)
-ose means sugar

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6
Q

Nomenclature: According tot he number of carbon atoms:

A 
trioses (monosacchrides containing 3 carbons)
tetroses (4)
pentoses (5)
hexoses (6)
heptoses (7)
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7
Q

Nomenclature: According to the presence of an aldehyde or ketone groups and number of carbon atoms

A
  • aldotriose and keto triose
  • aldotetrose and ketotetrose
  • aldopentoses and ketopentose
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8
Q

Trioses

A
  • aldotriose (glyceraldhyde)
  • ketotrioses (dihydroxyaceton)
  • review the structure
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9
Q

Tetroses

A

Monosaccharides containing 4 carbon atoms:
aldotetrose (erythrose)
ketotetrose (erythrulose)

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10
Q

Pentoses

A

5 carbon atoms
aldopentoses (ribose, arabinose, xylose, and lyxose)
ketopentoses (cellulose)

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11
Q

Function of pentoses

A

ATP GTP NAD NADP glycoproteins in animals and plants

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12
Q

Hexoses

A

Aldohexoses: glucose, mannose
ketohexose: fructose

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13
Q

What are the simplest monosaccharides?

A

the 2 three-carbon trioses:
D-glyceraldehyde (aldotriose)
dihydroxyacetone (ketotriose)

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14
Q

What are the most common monosaccharides in nature?

A

the aldohexose D-glucose

the ketohexose D-fructose

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15
Q

What are the components of nucleotides and nucleic acids?

A

the aldopentoses: D-ribose and 2-deoxy-D-ribose

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16
Q

Glucose is:

A
  • the most important sugar of CHO
  • the main sugar in blood
  • one of the major sources of energy
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17
Q

Glucose Properties

A
  • the straight-chain structural formula can account for some of the properties of glucose
  • however, a cyclic structure is thermodynamically favored and accounts for other properties
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18
Q

What is a cyclic structure formed by?

A

the reaction between the aldehyde group and a hydroxyl group

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19
Q

Many of the carbon atoms to which hydroxyl groups are attached are __________. This gives rise to the man _________ found in monosaccharides.

A

chiral centers

stereoisomers

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20
Q

Stereoisomers

A

isomers that differ in spatial arrangement of atoms

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21
Q

Isomerism

Sugars exhibit various forms of _____.

A

isomerism

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22
Q

Isomers

A

molecules that have the same chemical formula but different chemical structures

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23
Q

Asymmetric Carbon

A

an important determinant of isomerism

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24
Q

Asymmetric carbon (2)

A

a carbon atom to which 4 different atoms or groups of atom are attached is said to be asymmetric

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25
Q

Presence of asymmetric carbon also ________.

A

exhibits optical activity on the compound

26
Q

What happens when a beam of plane-polarised light is passed through a solution?

A

it will be rotated to the right or left in accordance with the type of compound

27
Q

The Optical Isomers:
When it is rotated to the right, the compound is called ______.
When it is rotated to the left, the compound is called ________.

A

Dextrorotatory (D or + sign)

Laevorotatory (L or - sign)

28
Q

What does the D-series and L-series refer to?

A

the orientation of the H and OH groups around the carbon atom just adjacent to the terminal primary alcohol carbon

29
Q

Which atom in glucose determines the series?

A

C-atom 5

30
Q

When the OH group on this carbon is on the right, it belongs to _______, when the - OH group is on the left, it is a member of _________.

A

D-series

L-series

31
Q

2 isomers of glucose- D-glucose and L-glucose are

A

mirror images of each other

32
Q

D- and L- isomers are

A

mirror images of each other (enantiomers)

33
Q

Examples of D-Aldoses with 3 carbons are

A

Glyceraldehyde

34
Q

Examples of D-Aldoses with 4 carbons are

A

D-erythrose

D-Threose

35
Q

Examples of D-Aldoses with 5 carbons are:

A

D-ribose
D-arabinose
D-xylose
D-lyxose

36
Q

Examples of D-Aldoses with 6 carbons are

A 
D-allose
D-altrose
D-glucose
D-mannose
D-gulose
D-idose
D-galactose
D-talose
37
Q

Examples of D-Ketoses with 3 carbons

A

Dihydroxyacetone

38
Q

Examples of D-Ketoses with 4 carbons

A

D-erythrulose

39
Q

Examples of D-Ketoses with 5 carbons

A

D-ribulose

D-xylulose

40
Q

Examples of D-Ketoses with 6 carbons

A

D-Psicose
D-Fructose
D-sorbose
D-tagatose

41
Q

Epimerism

A

2 sugars which differ from 1 another only in configuraion around a single carbon atom are called epimers

42
Q

Glucose and galactose are examples of

A

epimeric pairs which differ only with respect of C4

43
Q

Mannose and glucose are epimers in respect of

A

C2

44
Q

Epimerisation

A

process by which one epimer is converted to the other

it requires the enzyme epimerase

45
Q

What is an example of epimerisation?

A

conversion of galactose to glucose in the liver

46
Q

What is an example of epimerisation?

A

conversion of galactose to glucose in the liver

47
Q

The cyclic forms of carbohydrates can exist in 2 forms

A

a- and b-

48
Q

What are these 2 forms based on?

A

based on the position of the substituent at the anomeric center

49
Q

The 2 forms are sometimes described as _____ since they are _______ at the anomeric center

A

anomers, isomers

50
Q

When does a cyclic structure ‘take place’?

A

as the 2 reacting groups aldehyde and alcoholic group belong to the same molecule

51
Q

Mutarotation

A

during dissolving of a saccharide in water the equilibrium between anomers is established

52
Q

The rings structures of monosaccharides are similar to the ring structures of either

A

pryan or furan

53
Q

Define pyran and furan

A

a 6-membered ring

a 5-membered ring

54
Q

For glucose in solution, more than

A

99% is in the pyranose form

55
Q

The aldehyde and ketone moieties (parts) of the monosaccharides with 5 and 6 carbons will spontaneously react with

A

a hydroxyl group present in neighboring carbons to produce intramolecular hemiacetals or hemiketals (respectively)

56
Q

Hemiacetal or hemiketal formation results in the formation of

A

5 or 6 membered rings

57
Q

The 5 membered ring structure resembles the ____, thus sugars with this structure are called __________.

A

furan

furanoses

58
Q

Those with 6 membered rings resemble the _______ and are termed _______.

A

pyran

pyranoses

59
Q

Pyranoses =

A

aldohexoses

60
Q

Furanoses =

A

fructose ribose

61
Q

Due to the presence of a free aldehyde or ketone group, carbohydrates are readily _______ and behave as _______ ________.

A

oxidized , reducing agents

62
Q

These sugars have the capacity to reduce _____ to ______. Therefore, only the reducing sugars like ____ will give ______ _______.

A

Cupric ion (Cu 2+) , cuprous ion (Cu+) , glucose, positive reactions

Biochemistry (25 decks)

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