carbohydrates Flashcards
what are carbohydrates?
they are hydrated carbons, usually made up of carbon, hydrogen and oxygen. they are known as saccharides. they are of two types small and large. small (biomicromolecules) are further divided into derived monosaccharides, monosaccharides, ogliosacchrides. and the large are called poly sacchrides .
explain monosaccharides?
1) they are carbohydrates with a single sugar unit.
2) they are colourless, they are sweet in taste
3) empirical formula: CnH2nOn
4) they cannot be hydrolysed further and has 3 - 7 carbons.
n= 3 , C3H6H3 : trioses:
eg: glyceraldehyde(aldose , hydroxyacetone(ketone
n= 4, C4H8H8 :tetroses
eg : erythroses
n = 5 , C5H10O5: pentoses :
ribose, jeoxyribose
n = 6 , C6H12O6 , Hexoses;
eg: glucose , fructose
n = 7 , C7H14O7 , heptose;
eg:pseudo heptose
explain derived monosaccharides.
1) they are modified monosaccharides.
- Glycoside: sugar + sterol/ glycerols
eg: streptomycin (antibodies)
- deoxyribose: deoxygenation of ribose
- sugar alcohol: reduction of sugar
g: mannitols(brown algae)
- sugar-acid: re-oxidation of aldehydes and alcoholic sugars
eg: ascorbic acid (vitamin c), glucoroin acid
what glycosidic bonds?
they are bonds formed between the aldehyde or ketone group of one unit of monosaccharide and the alcohol group of another.
explain oligosaccharides
1) disaccharides: carbohydrates with two sugar units. - sucrose, ala cane sugar , beet sugar , table sugar.
obtained from beta Vulgaris, Saccharum, officinarum etc.
2)maltose: obtained from grinding cereals, seeds etc
3) lactose: milk sugar
formed in lactating mammary glands by the condensation of D glucose and D galactose
4) trehalose: found in the cacoon of trehala, haemolymph of some insects and it is made up of 2 glucose units
what is reducing sugar?
sugars that contain free aldehyde and ketone group. eg : glucose and fructose
explain the fehlings test
Fehling’s test is a chemical test used to differentiate between reducing and non-reducing sugars. This test can also be used to differentiate between carbohydrates and liquid carbohydrates in the ketone functional community.
1) glucose solution + Fehling’s / benedicts reagent ==
a) color changes to brick red
b) thus , it is a reducing sugar
c) cu ^2+—>cu ^+
2) sucrose solution + benedict’s \ Fehling’s reagent ==
a) color remains blue
b) non reducing sugar
state the units and bonds of types of disaccharides.
1) sucrose : - unit : alpha glucose + beta fructose
- bond : alpha 1 - beta 2 (non reducing)
2) maltose : : - unit : alpha glucose + alpha glucose
- bond : alpha 1 - 4 ( reducing)
3) lactose : : - unit : beta galactose + beta glucose
- bond : beta 1 -4 (reducing)
4) trehalose : : - unit :alpha glucose + alpha glucose
- bond : alpha 1 - 1(non reducing)
5) cellulose : - unit :beta glucose + beta glucose
- bond : beta 1 - 4 (reducing)
what are the other types of oligosacharides?
1) trisaccherides : - no. unites : 3
- example: raffinose
- units : glucose + fructose + galactose
2) tetrasacchrides : - no. unites : 4
- example: stachyose
- units : glucose + fructose + 2galactose
3) pentasacchrides : - no. unites : 5
- example: barbascoses–legumes
- units : 2glucose + fructose + 2galactose
what are poplysacchrides?
1) long chains of carbohydrates made up of more than 6 sugar units.
2) not sweet in taste
3) easily stored in the body
4) right end is reducing while left end is non reducing
what are the two types of poly achrides
1) homopolysachrides
2) heteropolysachrides
what are homoploysacchrides/
carbohydrates formed by similar monosacchrides units .
what are hetero polysacchrides?
carbohydrates made up of different types of monosacchrid units
explain startch .
- cornstarch , potato starch, chick peas
- storage polysaccharides ;
a) amylose
b) amylopectin
what are amylose ?
- straight chain
- 500 to 20,000 residues
- alpha glucose are bound by alpha 1 - 4 glycosidic bonds
- amylase becomes deep blue color on reaaction whit iodine
