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Flashcards in Carbohydrates Deck (74):
1

what are the two simplest monosaccharides?

-glyceraldehyde (an aldostriose)
-dihydroxyacetone (a ketotriose)

2

what is the classification of monosaccharides based on?

number of carbons:
-triose (3)
-tetrose (4)
-pentose (5)
-hexose (6)
-heptose (7)

3

of the triose monosaccharides, which are aldoses and which are ketoses?

-aldoses: glycerose/glyceraldehyde
-ketoses: dihydroxyacetone

4

of the tetrose monosaccharides, which are aldoses and which are ketoses?

-aldoses: erythrose
-ketoses: erythrulose

5

of the pentose monosaccharides, which are aldoses and which are ketoses?

-aldoses: ribose, xylose, arabinose
-ketoses: ribulose, xylulose

6

of the hexose monosaccharides, which are aldoses and which are ketoses?

-aldoses: glucose, galactose, mannose
-ketoses: fructose

7

of the heptose monosaccharides, which are aldoses and which are ketoses?

-aldoses: glucoheptose, galactoheptose
-ketoses: pseudoheptulose

8

what is an isomer?

same molecular formula but different structures

9

what are constitutional isomers?

differ in the order of attachment of atoms

10

what are stereoisomers?

-atoms are connected in the same order but differ in spatial arrantment
-can be enantiomers or diastereoisomers

11

what are enantiomers?

a type of stereoisomer that has a nonsuperimposable mirror image

12

what are diastereoisomers?

a type of stereoisomer that are not mirror images

13

what are epimers?

a type of diastereoisomer that differs at one of several asymmetric carbon atoms

14

what are anomers?

a type of diastereoisomer that differs at a new asymmetric carbon formed on ring closure

15

what is this?

D-glucose, monosaccharide, an aldohexose

16

what is this?

D-fructose, monosaccharide, a ketohexose

17

are most CHOs in the D or L form?

D form

18

what are D-ribose and 2-deoxy-D-ribose?

-monosaccharides

-aldopentoses

19

name 3 projection models of molecules

-ball and stick models
-fischer projections
-haworth projections

20

name a D-aldotriose

-D-glyceraldehyde
-it is a monosaccharide

21

name a D-aldotetrose

-D-erythrose
-it is a monosaccharide

22

name three D-aldopentoses

-D-ribose -
D-arabinose
-D-xylose
-these are monosaccharides

23

name three D-aldohexoses

-D-glucose
-D-mannose
-D-galactose
-these are monosaccharides

24

what is this?

-D-galactose
-monosaccharide 
-D-aldohexose

25

name a D-ketotriose

-dihydroxyacetone
-this is a monosaccharide

26

name a D-ketotetrose

-D-erythrulose

-this is a monosaccharide

27

name two D-ketopentoses

-D-ribulose

-D-xylulose

28

name a D-ketohexose

-D-fructose

29

describe how D-mannose and D-galactose are epimers of D-glucose

-D-mannose is an epimer at C-2

-D-galactose is an epimer at C-4

30

what forms a hemiacetal and acetal?

aldehyde and alcohol forms a hemiacetal, and adding a second alcohol forms an acetal

31

what forms a hemiketal and ketal?

ketone and alcohol forms a hemiketal, and adding a second alcohol forms a ketal

32

does glucose form a hemiacetal or hemiketal?

hemiacetal

33

does fructose form a hemiacetal or hemiketal?

hemiketal

34

describe pyranose formation from D-glucose

-the OH group on the 5th carbon reacts with the aldehyde group on the 1st carbon to form a ring

-in the alpha form, the OH group on the 1st carbon points down

-in the beta form, the OH group on the 1st carbon points up

35

describe furanose and pyranose formation from D-fructose

-a 5-membered ring forms furanose

-a 6-membered ring forms pyranose

36

D-glucopyranose forms chair and boat conformations. Which is more stable?

-chair conformation is more stable

-it is also more common

37

what is a reducing sugar?

-all monosaccharides and most disaccharides are reducing sugars

-it is any sugar that is capable of acting as a reducing agent (aka capable of oxidizing) because it has a free aldehyde group or a free ketone group

-reducing sugars can be identified as having anomeric carbons with an OH group

 

38

what two monosaccharides form maltose?

-glucose

-maltose is made via condensation, and it is broken down via hydrolysis

39

what two monosaccharides form sucrose?

glucose and fructose

40

what two monosaccharides form lactose?

glucose and galactose

41

what two monosaccharides for trehalose?

-glucose and glucose

-it is not a reducing sugar because both anomeric carbons are compromised (no OH group attached)

42

what linkage does the polysaccharide cellulose contain, and what is the enzyme needed to break it that humans do not have?

-beta 1-4 linkage

-cellulase

-cellulose is part of the microfibril structure of plant cell walls

43

describe the structure of starch

amylose is linear and contains alpha 1-4 linkages for the first 50 residues, and then turns into amylopectin which has big branches of alpha 1-6 linkages

44

describe the structure of glycogen

-for every 10 residues of alpha 1-4 linkages, there will be an alpha 1-6 linkage

45

what is the difference between homopolysaccharides and heteropolysaccharides?

-homopolysaccharides are composed of 2 or more of the same monomer

-heteropolysaccharides are composed of 2 or more different monomers

46

what is chitin?

it is a structural carbohydrate containing N-acetyl glucosamine units in beta 1-4 linkages

47

what is the function of glycogen?

it is a storage CHO

48

describe N- and O-glycosylation

-forms heteropolysaccharides

-monomers in O-glycosylation are linked to oxygen

-monomers in N-glycosylation are linked to nitrogen

49

what are the structural differences between glycoproteins and proteoglycans?

glycoproteins:

  • protein w/oligosaccharide chain covalently attached to polypeptide side chain
  • short, branched CHO chain; may be negatively charged

proteoglycans:

  • subclass of glycoproteins
  • core protein with 1+ covalently attached GAG chains
  • long, linear, negatively charged CHO polymer chains

50

how do glycoproteins and proteoglycans differ in their categorization?

glycoproteins

  • N-linked or O-linked

proteoglycans

  • based on the nature of their GAG chains

51

how do glycoproteins and proteoglycans differ functionally?

glycoproteins

  • cell-cell recognition (ex. ABO blood group antigens)

proteoglycans

  • modulation of cell growth processes or cushioning in joints

52

where are glycoproteins and proteoglycans found?

glycoproteins

  • found on cell surfaces
  • most are integral membrane proteins

proteoglycans

  • found mainly in CT
  • contribute to the organization and physical propeties of the ECM

53

what are 3 glycoconjugates and where are they found?

-proteoglycans, glycoproteins, and glycolipids

-they are found in the plasma membrane

54

name 4 glycosaminoglycans

  1. hyaluronate
  2. chondroitin 4-sulfate
  3. keratan sulfate
  4. heparin - injectable anticoagulant (important in dentistry)

55

what are some characteristics of glycosaminoglycans?

-large polysaccharides with amines

-high molecular weights

-negatively charged

-unusual structures

56

describe how CHOs are informational molecules

the span the plasma membrane and can present things such as antigens, receptors, toxins, viruses, and bacteria

57

what CHO is found in saliva?

mucins

58

what is this?

  • glyceraldehyde
  • aldotriose
  • monosaccharide

59

what is this?

  • dihydroxyacetone
  • ketotriose
  • monosaccharide

60

what is this?

  • D-ribose
  • aldopentose
  • monosaccharide

61

what is this?

  • D-erythrose
  • aldotetrose
  • monosaccharide

62

what is this?

  • D-erythrulose
  • ketotetrose
  • monosaccharide

63

what is this?

  • D-ribulose
  • ketopentose
  • monosaccharide

64

what is this?

  • maltose
  • glucose + glucose; condensation rxn
  • disaccharide

65

what is this?

  • lactose
  • glucose + galactose
  • disaccharide

66

what is this?

  • sucrose
  • glucose + fructose
  • disaccharide

67

stereochemistry:

glyceraldehyde and dihydroxyacetone are ____.

constitutional isomers

68

stereochemistry:

D-glyceraldehyde and L-glyceraldehyde are ____, which is a type of ____.

enantiomers; stereoisomer

69

stereochemistry:

D-altrose and D-glucose are ____, which is a type of ____.

diastereoisomers, stereoisomer

70

stereochemistry:

alpha- and beta-glucose are ____, a type of ____.

anomers; diastereoisomer

71

stereochemistry:

D-glucose and D-mannose are ____, which are types of ____.

epimers, diastereoisomers

72

T or F:

D and L isomers of a sugar are enantiomers

true

73

T or F:

the position of the ketone gives ketoses one more assymetric center than their isometric aldoses

false:

it gives ketoses one less assymetric center than their isometric aldoses

74

what is the only disaccharide that is not a reducing sugar?

sucrose