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CHEM 153 LAB > MIDTERM: CARBOHYDRATES > Flashcards

MIDTERM: CARBOHYDRATES Flashcards

1
Q

polyhydroxy aldehydes or ketones or substances that yield them upon hydrolysis ; constitute the major material by weight in our diet and serve as a source of energy

A

carbohydrates

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2
Q

carbohydrates not decomposable to simple sugars by hydrolysis ; all free _ are ‘reducing’ carbohydrates

A

monosaccharides

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3
Q

monosaccharides used in the experiment

A

arabinose
glucose
fructose
galactose

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4
Q

aldohexose monosaccharide used in the experiment

A

glucose
galactose

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5
Q

aldopentose monosaccharide used in the experiment

A

arabinose

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6
Q

ketohexose monosaccharide used in the experiment

A

fructose

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7
Q

a component of complex plant polysaccharides called gums and found in the free state in the wood of conuferous trees (evergreen trees of shurbs)

A

arabinose

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8
Q

also called grape sugar and dextrose ; referred to as blood sugar

A

glucose

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9
Q

fruit sugar ; sweetest tasting of all sugars

A

fructose

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10
Q

also called cerebrose or brain sugar ; found in cerebrosides

A

galactose

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11
Q

contains two simple sugars linked by glycosidic bond

A

disaccharides

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12
Q

glucose + glucose ; malt sugar ; a-D-glucose + a-D-glucose

A

maltose

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13
Q

glucose + galactose ; milk sugar ; B-D-glucose + B-D-glucose

A

lactose

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14
Q

glucose + fructose ; table sugar ; found in sugar cane, sugar maple, and sugar beets ; a-D-glucose + B-D-glucose

A

sucrose

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15
Q

contains two or ten simple sugars which are linked by glycosidic bond

A

oligosaccharides

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16
Q

have nine or more monosaccharides linked together by glycosidic bonds ; found in nature serve either a structural or a nutrient function

A

polysaccharides

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17
Q

polysaccharides used in the experiment

A

starch
agar-agar
gum-arabic
dextrin
cellulose (cotton)

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18
Q

found in seeds, tubers, and roots of plants such as as potatoes, corn, and cassava ; comprising glucose monomers joined in a(1-4) and a(1-6) linkages

A

starch

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19
Q

two components of starch

A

amylose
amylopectin

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20
Q

partial hydrolytic products of starch ; mixture of polymers of d-glucose units linked by a(1-4) or a(1-6) glycosidic bonds ; shorter chains, used in infant food and corn syrup

A

dextrin

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21
Q

used as a storehouse (liver) muscles of _ in an animal system

A

glycogen

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22
Q

most abundant organic compounds on earth ; dry leaves contains 10-20% ; wood 50% ; cotton 90% ; a linear polymer made up of B(1-4) glycosidic bonds

A

cellulose or cotton

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23
Q

jelly like subtance obtained from the cell walls of some species of red algae, ogonori and tengusa ; mixture of two components ; vegan substitute for gelatin

A

agar-agar

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24
Q

two components of agar-agar

A

linear polysaccharide aganose
heterogenous mixture of smaller molecules called agaropectin

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25
Q

complete hydrolysis of agar-agar yields

A

galactose

26
Q

dried water soluble exudate from the stems of Acacia senegal or related species ; carbohdyrate polymer, complex and highly branched, used in pharmaceutical preparations

A

gum-arabic

27
Q

what are the 9 tests in carbohydrates

A

molisch
anthrone
iodine test for polysaccharides
benedict’s
barfoed’s
seliwanoff’s
orcinol
osazone
mucic acid

28
Q

this test distinguishes carbohydrates from non-carbohydrates

A

molisch test

29
Q

in molisch test, the carbohydrate undergoes dehydration in the presence of concentrated sulfuric acid resulting in the formation of an

A

aldehyde

30
Q

what are the components of molisch reagent

A

5% a-naphtol in 95% ethanol

31
Q

what is the indication of a positive molisch test (indication of presence of carbohydrate)

A

purple ring between layers

32
Q

qualitative and quantitative estimation of polysaccharides and monosaccharides; sulfuric acid hydrolyzes bound sugars and reacts with sugars to yield furfural or furfural dervatives

A

anthrone test

33
Q

positive indication of anthrone test

A

deep green or blue colored complex

34
Q

what are the components of anthrone reagent

A

0.2% anthrone in conc, H2SO4

35
Q

in anthrone test, if milkiness occurs, dilute carefully with

A

50% H2SO4

36
Q

used to differentiate helical polysaccharides from non-helical polysaccharides ; distinguishes strach from monosaccharides, disaccharides, and other polysaccharides

A

iodine test for carbohydrates

37
Q

iodine yields what color in the presence of starch and dextrin indicating a positive result

A

bluish black (blue-black colored solution)

38
Q

glycogen reacts with the reagent to give what color

A

brown-blue color

39
Q

the darker the color in iodine test means

A

presence of starch

40
Q

general test for detecting presence of reducing sugars

A

benedict’s test

41
Q

benedict’s reagent is composed of

A

Cu2+ ions in alkaline solution with sodium citrate

42
Q

specific components of benedict’s reagent

A

copper sulfate pentahydrate (copper II)
sodium carbonate
sodium citrate

43
Q

what is an indication of a positive test for benedict’s test

A

deep red color (brick red)

44
Q

distinguish between monosaccharides and reducing disaccharides ; uses copper (II) ions in a slightly acidic medium

A

barfoed’s test

45
Q

what is a COMMON positive indication of the barfoed’s test

A

red precipitate of copper (I) oxide within two to three minutes

46
Q

in barfoed’s test what are the other colors that note a positive test within three minutes

A

green
red
yellow

47
Q

used to distinguish aldose from ketose ; 5-hydroxymethylfurfural reacts with resorcinol present in the test reagent

A

seliwanoff’s test

48
Q

what is a positive indication of seliwanoff’s test

A

red or cherry red product

49
Q

test for distinguishing pentoses from hexoses

A

orcinol test

50
Q

what is the composition of orcinol reagent

A

5 methylresorcinol
conc HCl
FeCl3 catalyst

51
Q

what gives a positive response in orcinol/bial’s test

A

arabinose

52
Q

test for reducing sugars ; involves hydrazone formation at C-1 of an aldose and oxidation of C-2 of an alcohol group to a ketone

A

osazone test

53
Q

what is the positive indication of osazone test

A

yellow colored crystals

54
Q

results of osazone test: fructose

A

2 mins

55
Q

results of osazone test: glucose

A

4-5 minutes

56
Q

results of osazone test: arabinose

A

10 minutes

57
Q

results of osazone test: galactose

A

15-19 minutes

58
Q

results of osazone test: lactose

A

precipitated when cooled

59
Q

results of osazone test: maltose

A

precipitated when cooled

60
Q

results of osazone test: sucrose

A

none

61
Q

to detect presence of galactose and lactose

A

mucic acid test

62
Q

positive indication of mucic acid test

A

colorless needle like crystals

CHEM 153 LAB (7 decks)

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