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Biochemistry > Chapter 2: Carbohydrates > Flashcards

Chapter 2: Carbohydrates Flashcards

1
Q

1.Monosaccharides undergo dehydration when treated with?
2.How many water molecules are released?
3. Dehydration products pf hexoses and pentoses?

A
  1. Conc. Sulphuric acid
  2. 3 water molecules
  3. Hexoses:
    - hydroxymethyl furfural
    Pentoses:
    - furfural
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2
Q

1.Furfurals can condense with ______ compounds to form coloured products.
2. It is the chemical basis of which test?

A
  1. Phenolic compounds
  2. Molisch’s test
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3
Q

Which test is used for detection of xylose in urine in essential pentosuria?

A

Bial’s test

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4
Q

What happens in Bial’s test?

A

Pentoses react with strong HCl to form furfural derivatives which in turn react with orcinol to form green coloured complex

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5
Q

What is mucic acid test?

A

Galactose when react with nitric acid and forms insoluble mucic acid crystals

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6
Q

What are osazone?

A

Osazones are crystalline compounds formed by the reaction of reducing sugars with phenylhydrazine.
(When boiled)

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7
Q

Which 2 carbons are involved in osazone formation?

A

C1 and C2

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8
Q

List the osazones of glucose, fructose, mannose, maltose and lactose?

A

Glucose, Fructose, and Mannose = needle-shaped osazone (same)

Maltose = Sunflower-shaped
Lactose = powder-puff shaped

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9
Q

Esterfication of carbohydrates occurs with which acid? Give an example of esters?

A
  1. Phosphoric acid
  2. Examples;
    Glucose-6-phosphate
    Glucose-1-phosphate
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10
Q

1.What are glycosides?
2.What bond is present?
3. What is aglycone?

A

Glycoside are formed when hemiacetal/ketal Hyrdoxyl group (-OH) (alcohol + aldehyde/ketone)
of a carbohydrate react with (-OH) group of another carbohydrate or non-carbohydrate.

  1. The bond so formed is known as glycosidic bond
  2. And the non-carbohydrate (when present) is called aglycone
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11
Q

Name the glycosidic bonds in
maltose
Glycogen
Starch (amylase, amylopectin)
sucrose
Inulin
lactose
Cellulose
Chitin

A

1.maltose = a-1,4
2.Glycogen = a-1,4 , a-1,6
3.Starch =
(amylase: a-1,4 ,
amylopectin: a-1,4 , a-1,6)

4.sucrose = a-1, B-2

5.Inulin = B-2,1
6.lactose = B-1,4
7.Cellulose = B-1,4
8.Chitin = B-1,4

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12
Q

Which glycoside is used in treatment of tuberculosis?

A

Streptomycin
- an antibiotic

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13
Q

What are cardiac glycosides?

A

These are the steroid glycosides

Digoxin and Digitoxin
- contain aglycone steroid
- stimulate muscle contraction

Oubain
- inhibits Na-K ATPase and blocks the transport of Na+

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14
Q

Which glycoside imparts vanilla flavour?

A

Glucovanillin
(Vanillin-D-glucoside)

  • natural substance
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15
Q

Which glycoside produces renal damage in experimental animals?

A

Phlorhizin

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16
Q

Gluconic acid and Glucoronic acid is produced from glucose by oxidation of?

A

Gluconic acid
Oxidation of aldehyde (C1 group)

Glucoronic acid
Oxidation of primary alcohol group (C6)

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17
Q

Reduction of aldehyde or ketone of glucose produces _______?
And of mannose produces _____?

A
  1. Sorbitol
  2. Mannitol
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18
Q

_______ &__________ when accumulate in tissues causes strong osmotic effect leading to swelling of cells, and certain pathological effect e.g Cataract, peripheral neuropathy, nephropathy.

A

Sorbitiol (reduction of glucose)
Dulcitol (reduction of galactose)

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19
Q

__________ is used to reduce intracranial tension by forced diuresis (increased urine output?

A

Mannitol (reduction of mannose)

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20
Q

______ is a sweetner used in sugarless gums and candies?

A

Xylitol
An alditol (polyhydroxy alcohols formed by reduction of monosaccharides)

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21
Q

_______ alditol is a constituent of flavin coenzyme?
_______&_______ alditols are components of lipids?

A

1.Ribitol
2. Glycerol & myo-inositol

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22
Q

What are amino sugars?
Where are they present

A

(-OH ) of monosaccharides replaced by amino group
E.g
D-glucosamine
D-galactosamine

Present as constituents of heteropolysaccharides

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23
Q

What is NANA?
And what is Sialic Acid?

A

N-AcetylNeuraminicAcid or NANA is a derivative of :
N-acetylmannose &
Pyruvic acid
-Constituent of glycoprotein and glycolipids

2.Term Sialic acid is used to include NANA and its other derivatives

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24
Q

An antibiotic containing aminosugars?

A

Erythromycin

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25
Q

The vitamin having structure closely resembling to that of a monosaccharide?

A

L-Ascorbic Acid or Vitamin C

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26
Q

Which staining can specifically detect deoxyribose and thus DNA in tissues?

A

Feulgen staining

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27
Q

_______ is a deoxy L-galactose found in blood group antigens and certain glycoproteins?

A

Fucose

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28
Q

Examples of reducing and non- reducing disaccharides?

A

reducing
maltose, lactose

Non-reducing
Sucrose
Trehalose (found in bacteria, fungi, yeast, insects, plants)

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29
Q

Which glycosidic bond is present in iso-maltose?

A

a-1,6
( normal maltose: a-1,4)

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30
Q

What is cellubiose?
Structural similarity?
Glycosidic linkage?

A

Cellubiose is a disaccharide formed during hydrolysis of cellulose

Structurally similar to maltose

Glycosidic linkage: B-1,4

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31
Q

Which sugar is cane sugar or sugar of commerce?

A

Sucrose

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32
Q

Sucrose is made up of?

A

Glucose (a-1) + fructose (B-2)

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33
Q

Which disaccharide can’t form osazone?

A

Sucrose
(No free aldehyde or ketone (reducing) group)

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34
Q

What is inversion? And which sugar is known as invert sugar?

A

Change in optical rotation from dextro(+)— to —levo(-)rotatory is known as inversion

Sucrose— Invert sugar
Hydrolysed mixture of sucrose containing glucose and fructose is called invert sugar

First sucrose — dextro(+) (+66.5)
But when hydrolysed — levo(-) (-28.2)

35
Q

1.Most used artificial sweetener?
2.Name other common sugar substitutes?

A

1.Sucralose (trichlorosucrose)
About 500 times sweeter than sucrose

  1. Saccharin
    Cyclamate
    Aspartame
    Acesulfame-Potassium
36
Q

What is lactulose?
It is used for the treatment of which disorder?
And how?

A

A synthetic disaccharide
Containing galactose + Fructose

-for the treatment of Hepatic encephalopathy (liver doesn’t work properly & it effects the brain)
Characterized by high plasma ammonium level

  • lactulose converts (NH3+) to ammoniun ion (NH4+) ——— reduction in plasma NH3. Since NH4+ ions are not easily absorbed
37
Q

Types of polysaccarides?

A

2:
1. Homopolysaccharides
(On hydrolysis—single type of monosaccharide:
Glucans —polymer of glucose
Fructosans—polymers of fructose

  1. Heteropolysaccharide
    (On hydrolysis— mixture)
38
Q

Starch exists in which 2 forms?

A

Amylose (15-20%)
-Unbranched
-water-soluble
-200—1000 glucose units

Amylopectin (80-85%)
-Branched
-Water-insoluble
- 20-30 glucose units per branch

39
Q

Amylase acts specifically on _______bonds?

A

a-1,4 glycosidic

40
Q

What are dextrins?

A

Breakdown products of starch

In sequence starch breaks down into:

Starch—–different dextrins—- finally to maltose and glucose

41
Q

Iodine colouration of
Soluble starch
Amylodextrin
Erythrodextrin
Achrodextrin

A

Soluble starch: blue
Amylodextrin: violet
Erythrodextrin: red
Achrodextrin: no colour

42
Q

What are dextrans?
Uses?

A

Polymers of glucose produced by microorganisms

Used as:
1.Plasma volume expanders in transfusion
2. Chromatography (e.g gel filtration)

43
Q

Kidney function can be assessed through?
Which polysaccharide is used for it?

A

1.Measurement of glomerular Filtration rate by **inulin Clearance Test

  1. Inulin
44
Q

A polymer of fructose that occurs in dahlia bulb, onions, garlic?

A

Inulin

45
Q

Glycogen is an animal starch with highest concentration in? Is it present in plants?

A

In liver followed by muscle, brain etc

In plants that donot possess chlorophyll (e.g yeast, fungi)

46
Q

What is glycogenin?
Where is it present in glycogen molecule?

A

Glycogenin is a protein that plays a crucial role in the synthesis of glycogen.
It acts as a primer for glycogen synthesis by initiating the formation of the glycogen molecule and serving as the starting point for the attachment of glucose units.

-at the centre of glycogen molecule

47
Q

Structure of glycogen is similar to?

A

Amylopectin ,
( a-1,4 and a-1,6)
But with more number of branches

48
Q

__________ of sucrose (of chocalate and candies) resulting in ________, causes dental carries (destruction of teeth)?

A

1.Fermentation
2. Organic acids

49
Q

Importance of non-digestible carbohydrates such as cellulose and dietry fibres?

A

Decrease intestinal absorption of glucose and cholesterol
Increase bulk of faeses to avoid constipation

50
Q

Chitin is composed of which units?

A

N-acetyl glucose amine

51
Q

Mucopolysaccharides are _______ made of repeating units of sigar derivatives, namely ________ & ______?

A
  1. Heteroglycans or heteropolysacchaides
  2. Amino sugars & uronic acids
52
Q

What are uronic acids?

A

Uronic acids are a type of sugar acid that contain a:
carboxylic acid group and a carbonyl group.

They are commonly found in the form of sugar derivatives, such as glucuronic acid and iduronic acid.

53
Q

Mucopolysaccharides are more commonly known as?

A

Glucosaminoglycans (GAGs)

54
Q

What is present in GAG structure?
Why are they called acid mucopolysaccharides?

A
  1. Acetylated amino acids
  2. Sulfate
  3. Carboxyl groups

Presence of Sulfate & Carboxyl groups make them acidic

55
Q

What are mucoids?

A

Mucopolysaccharides + proteins = mucoproteins or mucoids or proteoglycans

95% —- carbohydrate
5% —— protein

56
Q

In tissue structure, mucopolysaccharides are present in?

A

Ground substance of extracellular matrix

57
Q

Name important mucopolysaccharides?

A
  1. Hyaluronic acid
  2. Chondroitin-4-sulfate
  3. Heparin
  4. Dermatan sulfate
  5. Keratan sulfate
58
Q

Hyaluronic acid is present in?

A

Ground substance of:
1.Synovial fluid of joints
(Lubricant and shock absorber in joint) + wound healing
2.Vitreous humor of eyes
3.Gel around ovum
4.connective tissue

59
Q

1.Hyaluronic acid is composed of which units?

2.Which bond is present between the disaccharides formed by these units?

  1. Molecular weight of hyaluronic acid?
A
  1. D-glucoronic acid + N-acetyl-D-glucosamine
  2. B(1—–3) glycosidic bond
  3. Upto 4 million
60
Q

Which enzyme breaks B(1–4) linkages in hyaluronic acid?

  1. Where is this enzyme mostly present?
  2. Its importance?
A

Hyaluronidase enzyme breaks the β(1—4) glycosidic linkages in hyaluronic acid and other GAG

  1. High conc in;
    Testes
    Seminal fluid
    Snake
    Insect venom
  2. In semen
    Imp for fertilization
    - clears the gel (hyaluronic acid) around ovum—- allows penetration
    In bacteria
    Invasion into animal tissue
61
Q

1.Chondroitin sulfate is composed of which disaccharide units?

  1. It is structurally comparable with?
  2. It is present in?
A
  1. D-glucuronic acid & N-acetyl-D-galactosamine -4- sulfate
  2. Hyaluronic acid
  3. Various mammalian tissues;
    Bone
    Cartilage
    Skin
    Heart
    Valves
    Cornea
    Blood vessel walls
62
Q

The only difference between chondroitin sulfate and hyaluronic acid is the presence of (amino sugar). Which is?

A

Hyaluronic acid
N-acetyl D-glucosamine

Chondroitin Sulfate
N-acetyl D-galactosamine -4-sulfate

63
Q

The only non-sulfated GAG is?

A

hyaluronic acid.

64
Q

1.Heparin is composed of which alternating units?

2.occurance?

  1. Importance? Which Enzyme it releases?
A
  1. N-sulfo D-glucosamine 6-sulfate &
    Glucoronate-2-sulfate
  2. In
    Blood,
    Lung
    Liver
    Kidney
    Spleen
  3. Anticoagulant
    Release of enzyme lipoprotein lipase —— clears turbidity of lipemic plasma
    Used in intramuscular coagulaton
65
Q

1.Dermatan sulfate is structurally related to?

2.What is the difference in structure?

  1. Occurence?
A
  1. Chondroitin-4-sulfate
    (N-acetyl D-galactosamine
    + D-glucoronic acid)
  2. Only difference:
    Inversion in configuration
    Of C5 of D-glucoronic acid to form L-iduronic acid
  3. Skin
    Blood vessel valves
    Heart valves
66
Q

Keratan sulfate is composed of?

  1. It is found in?
A
  1. D-galactosamine & N-acetylglucosamine-6-phosphate
  2. Cornea
    Cartilage
    Connective tissue
67
Q

Variable sulfate content and small amounts of mannose, fructose and sialic acid is present in which heterogenous GAG?

A

Keratan sulfate

68
Q

Agar and pectin both being non-digestible serve as?

A

Dietry fibres

69
Q

1.Agar is a polymer of?
2.Mostly found in?

A
  1. Galactose
    Sulfate
    Glucose
  2. Sea weeds
70
Q

What is agarose?
Use?

A

Polysaccharide derived from agar.
Composed of galactose & anhydrogalactose

Used in;
Microbial culture media
Electrophoresis

71
Q

What is electrophoresis?

A

Electrophoresis is a technique used to separate molecules, such as DNA or proteins, based on their size and charge.

It involves applying an electric field to a gel matrix, like agarose, causing the molecules to migrate and separate.

72
Q

1.Pectins are composed of?
2. Found in?
3. Use?

A
  1. Galactouronate & rhamnose
  2. Found in apples and citrus fruit
  3. Preparation of jellies
73
Q

How glycoproteins (mucoproteins) are responsible for spread of cancer?

A

Alteration in the structure of glycoproteins of tumor cell membrane —- responsible for metastasis

74
Q

The term mucoproteins is used for glycoproteins with carbohydrate conc. more than?

A

More than 4%

75
Q

Glycophorins and lectins are category of ?

A

Glycoprotein

76
Q

What is glycophorin?
How much are they glycosylated and why?

A

1.Membrane protein of RBC
2. 60% forming a hydrophilic charged coat enabling RBC to circulate without adhering

77
Q

Fish that live below -2° (T at which blood would freeze) contain _______ glycoproteins that lower the freezing point of water?

A

Antifreeze glycoproteins

78
Q

Subgroup of lectins that is involved in cell-cell recognition & adhesion & movemnt of T-lymphocytes to site of inflammation?

A

Selectin

79
Q

Name the carbohydrates found in blood group antigens or blood group substances?

A

N-acetylgalactosamine
Galactose
Fucose
Sialic acid

80
Q

________ are the spherical shaped bodies of water, delivery system for bioactive molecules.

Where are the carbohydrates present in them?

A
  1. Aquasomes
  2. Central non-crystalline core coated with carbohydrate (polyhydroxy oligomers)
81
Q

Thyrotropin and erythropoeitin function as?

A

Hormones

82
Q

Function of fibronectin and laminin?

A

Cell-cell recognition and adhesion

83
Q

Function of intrinsic factor?

A

Absorption of vitamin B12

84
Q

Carbohydrates are the most abundant dietry source of enery __________ for all living organisms?

A

4 cal/g

Biochemistry (10 decks)

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