Chapter 2: Carbohydrates Flashcards
1.Monosaccharides undergo dehydration when treated with?
2.How many water molecules are released?
3. Dehydration products pf hexoses and pentoses?
- Conc. Sulphuric acid
- 3 water molecules
- Hexoses:
- hydroxymethyl furfural
Pentoses:
- furfural
1.Furfurals can condense with ______ compounds to form coloured products.
2. It is the chemical basis of which test?
- Phenolic compounds
- Molisch’s test
Which test is used for detection of xylose in urine in essential pentosuria?
Bial’s test
What happens in Bial’s test?
Pentoses react with strong HCl to form furfural derivatives which in turn react with orcinol to form green coloured complex
What is mucic acid test?
Galactose when react with nitric acid and forms insoluble mucic acid crystals
What are osazone?
Osazones are crystalline compounds formed by the reaction of reducing sugars with phenylhydrazine.
(When boiled)
Which 2 carbons are involved in osazone formation?
C1 and C2
List the osazones of glucose, fructose, mannose, maltose and lactose?
Glucose, Fructose, and Mannose = needle-shaped osazone (same)
Maltose = Sunflower-shaped
Lactose = powder-puff shaped
Esterfication of carbohydrates occurs with which acid? Give an example of esters?
- Phosphoric acid
- Examples;
Glucose-6-phosphate
Glucose-1-phosphate
1.What are glycosides?
2.What bond is present?
3. What is aglycone?
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.
- The bond so formed is known as glycosidic bond
- And the non-carbohydrate (when present) is called aglycone
Name the glycosidic bonds in
maltose
Glycogen
Starch (amylase, amylopectin)
sucrose
Inulin
lactose
Cellulose
Chitin
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
Which glycoside is used in treatment of tuberculosis?
Streptomycin
- an antibiotic
What are cardiac glycosides?
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+
Which glycoside imparts vanilla flavour?
Glucovanillin
(Vanillin-D-glucoside)
- natural substance
Which glycoside produces renal damage in experimental animals?
Phlorhizin
Gluconic acid and Glucoronic acid is produced from glucose by oxidation of?
Gluconic acid
Oxidation of aldehyde (C1 group)
Glucoronic acid
Oxidation of primary alcohol group (C6)
Reduction of aldehyde or ketone of glucose produces _______?
And of mannose produces _____?
- Sorbitol
- Mannitol
_______ &__________ when accumulate in tissues causes strong osmotic effect leading to swelling of cells, and certain pathological effect e.g Cataract, peripheral neuropathy, nephropathy.
Sorbitiol (reduction of glucose)
Dulcitol (reduction of galactose)
__________ is used to reduce intracranial tension by forced diuresis (increased urine output?
Mannitol (reduction of mannose)
______ is a sweetner used in sugarless gums and candies?
Xylitol
An alditol (polyhydroxy alcohols formed by reduction of monosaccharides)
_______ alditol is a constituent of flavin coenzyme?
_______&_______ alditols are components of lipids?
1.Ribitol
2. Glycerol & myo-inositol
What are amino sugars?
Where are they present
(-OH ) of monosaccharides replaced by amino group
E.g
D-glucosamine
D-galactosamine
Present as constituents of heteropolysaccharides
What is NANA?
And what is Sialic Acid?
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
An antibiotic containing aminosugars?
Erythromycin
The vitamin having structure closely resembling to that of a monosaccharide?
L-Ascorbic Acid or Vitamin C
Which staining can specifically detect deoxyribose and thus DNA in tissues?
Feulgen staining
_______ is a deoxy L-galactose found in blood group antigens and certain glycoproteins?
Fucose
Examples of reducing and non- reducing disaccharides?
reducing
maltose, lactose
Non-reducing
Sucrose
Trehalose (found in bacteria, fungi, yeast, insects, plants)
Which glycosidic bond is present in iso-maltose?
a-1,6
( normal maltose: a-1,4)
What is cellubiose?
Structural similarity?
Glycosidic linkage?
Cellubiose is a disaccharide formed during hydrolysis of cellulose
Structurally similar to maltose
Glycosidic linkage: B-1,4
Which sugar is cane sugar or sugar of commerce?
Sucrose
Sucrose is made up of?
Glucose (a-1) + fructose (B-2)
Which disaccharide can’t form osazone?
Sucrose
(No free aldehyde or ketone (reducing) group)
What is inversion? And which sugar is known as invert sugar?
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)
1.Most used artificial sweetener?
2.Name other common sugar substitutes?
1.Sucralose (trichlorosucrose)
About 500 times sweeter than sucrose
- Saccharin
Cyclamate
Aspartame
Acesulfame-Potassium
What is lactulose?
It is used for the treatment of which disorder?
And how?
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
Types of polysaccarides?
2:
1. Homopolysaccharides
(On hydrolysis—single type of monosaccharide:
Glucans —polymer of glucose
Fructosans—polymers of fructose
-
Heteropolysaccharide
(On hydrolysis— mixture)
Starch exists in which 2 forms?
Amylose (15-20%)
-Unbranched
-water-soluble
-200—1000 glucose units
Amylopectin (80-85%)
-Branched
-Water-insoluble
- 20-30 glucose units per branch
Amylase acts specifically on _______bonds?
a-1,4 glycosidic
What are dextrins?
Breakdown products of starch
In sequence starch breaks down into:
Starch—–different dextrins—- finally to maltose and glucose
Iodine colouration of
Soluble starch
Amylodextrin
Erythrodextrin
Achrodextrin
Soluble starch: blue
Amylodextrin: violet
Erythrodextrin: red
Achrodextrin: no colour
What are dextrans?
Uses?
Polymers of glucose produced by microorganisms
Used as:
1.Plasma volume expanders in transfusion
2. Chromatography (e.g gel filtration)
Kidney function can be assessed through?
Which polysaccharide is used for it?
1.Measurement of glomerular Filtration rate by **inulin Clearance Test
- Inulin
A polymer of fructose that occurs in dahlia bulb, onions, garlic?
Inulin
Glycogen is an animal starch with highest concentration in? Is it present in plants?
In liver followed by muscle, brain etc
In plants that donot possess chlorophyll (e.g yeast, fungi)
What is glycogenin?
Where is it present in glycogen molecule?
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
Structure of glycogen is similar to?
Amylopectin ,
( a-1,4 and a-1,6)
But with more number of branches
__________ of sucrose (of chocalate and candies) resulting in ________, causes dental carries (destruction of teeth)?
1.Fermentation
2. Organic acids
Importance of non-digestible carbohydrates such as cellulose and dietry fibres?
Decrease intestinal absorption of glucose and cholesterol
Increase bulk of faeses to avoid constipation
Chitin is composed of which units?
N-acetyl glucose amine
Mucopolysaccharides are _______ made of repeating units of sigar derivatives, namely ________ & ______?
- Heteroglycans or heteropolysacchaides
- Amino sugars & uronic acids
What are uronic acids?
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.
Mucopolysaccharides are more commonly known as?
Glucosaminoglycans (GAGs)
What is present in GAG structure?
Why are they called acid mucopolysaccharides?
- Acetylated amino acids
- Sulfate
- Carboxyl groups
Presence of Sulfate & Carboxyl groups make them acidic
What are mucoids?
Mucopolysaccharides + proteins = mucoproteins or mucoids or proteoglycans
95% —- carbohydrate
5% —— protein
In tissue structure, mucopolysaccharides are present in?
Ground substance of extracellular matrix
Name important mucopolysaccharides?
- Hyaluronic acid
- Chondroitin-4-sulfate
- Heparin
- Dermatan sulfate
- Keratan sulfate
Hyaluronic acid is present in?
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
1.Hyaluronic acid is composed of which units?
2.Which bond is present between the disaccharides formed by these units?
- Molecular weight of hyaluronic acid?
- D-glucoronic acid + N-acetyl-D-glucosamine
- B(1—–3) glycosidic bond
- Upto 4 million
Which enzyme breaks B(1–4) linkages in hyaluronic acid?
- Where is this enzyme mostly present?
- Its importance?
Hyaluronidase enzyme breaks the β(1—4) glycosidic linkages in hyaluronic acid and other GAG
- High conc in;
Testes
Seminal fluid
Snake
Insect venom -
In semen
Imp for fertilization
- clears the gel (hyaluronic acid) around ovum—- allows penetration
In bacteria
Invasion into animal tissue
1.Chondroitin sulfate is composed of which disaccharide units?
- It is structurally comparable with?
- It is present in?
- D-glucuronic acid & N-acetyl-D-galactosamine -4- sulfate
- Hyaluronic acid
- Various mammalian tissues;
Bone
Cartilage
Skin
Heart
Valves
Cornea
Blood vessel walls
The only difference between chondroitin sulfate and hyaluronic acid is the presence of (amino sugar). Which is?
Hyaluronic acid
N-acetyl D-glucosamine
Chondroitin Sulfate
N-acetyl D-galactosamine -4-sulfate
The only non-sulfated GAG is?
hyaluronic acid.
1.Heparin is composed of which alternating units?
2.occurance?
- Importance? Which Enzyme it releases?
-
N-sulfo D-glucosamine 6-sulfate &
Glucoronate-2-sulfate - In
Blood,
Lung
Liver
Kidney
Spleen -
Anticoagulant
Release of enzyme lipoprotein lipase —— clears turbidity of lipemic plasma
Used in intramuscular coagulaton
1.Dermatan sulfate is structurally related to?
2.What is the difference in structure?
- Occurence?
-
Chondroitin-4-sulfate
(N-acetyl D-galactosamine
+ D-glucoronic acid) - Only difference:
Inversion in configuration
Of C5 of D-glucoronic acid to form L-iduronic acid - Skin
Blood vessel valves
Heart valves
Keratan sulfate is composed of?
- It is found in?
- D-galactosamine & N-acetylglucosamine-6-phosphate
- Cornea
Cartilage
Connective tissue
Variable sulfate content and small amounts of mannose, fructose and sialic acid is present in which heterogenous GAG?
Keratan sulfate
Agar and pectin both being non-digestible serve as?
Dietry fibres
1.Agar is a polymer of?
2.Mostly found in?
- Galactose
Sulfate
Glucose - Sea weeds
What is agarose?
Use?
Polysaccharide derived from agar.
Composed of galactose & anhydrogalactose
Used in;
Microbial culture media
Electrophoresis
What is electrophoresis?
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.
1.Pectins are composed of?
2. Found in?
3. Use?
- Galactouronate & rhamnose
- Found in apples and citrus fruit
- Preparation of jellies
How glycoproteins (mucoproteins) are responsible for spread of cancer?
Alteration in the structure of glycoproteins of tumor cell membrane —- responsible for metastasis
The term mucoproteins is used for glycoproteins with carbohydrate conc. more than?
More than 4%
Glycophorins and lectins are category of ?
Glycoprotein
What is glycophorin?
How much are they glycosylated and why?
1.Membrane protein of RBC
2. 60% forming a hydrophilic charged coat enabling RBC to circulate without adhering
Fish that live below -2° (T at which blood would freeze) contain _______ glycoproteins that lower the freezing point of water?
Antifreeze glycoproteins
Subgroup of lectins that is involved in cell-cell recognition & adhesion & movemnt of T-lymphocytes to site of inflammation?
Selectin
Name the carbohydrates found in blood group antigens or blood group substances?
N-acetylgalactosamine
Galactose
Fucose
Sialic acid
________ are the spherical shaped bodies of water, delivery system for bioactive molecules.
Where are the carbohydrates present in them?
- Aquasomes
- Central non-crystalline core coated with carbohydrate (polyhydroxy oligomers)
Thyrotropin and erythropoeitin function as?
Hormones
Function of fibronectin and laminin?
Cell-cell recognition and adhesion
Function of intrinsic factor?
Absorption of vitamin B12
Carbohydrates are the most abundant dietry source of enery __________ for all living organisms?
4 cal/g
