Carbohydrates Flashcards
Three elements that all carbohydrates are made of
Carbon, oxygen and hydrogen
Uses of carbohydrates
Used as energy sources and structural materials in organisms
Three main groups of carbohydrates and brief description
-monosaccharides(simple sugars)
-disaccharides(two monosaccharides)
-polysaccharides(large molecules formed from many monosaccharides)
Three types of monosaccharides
-glucose(alpha and beta)
-fructose
-galactose
Basic structure of monosaccharides
-contain C double bonded to O(carbonyl group) and at least two OH(hydroxyl groups) which take part in reactions
Structure of glucose
Contains 6 carbon atoms arranged in hexagon so is a hexose sugar
-C6H12O6
-highly soluble and is main form in which carbohydrates are transported around body
-exist as two structural isomers: alpha and beta
Difference between glucose’s two structural isomers
-alpha glucose has OH group attached below carbon 1
-beta glucose has OH group attached above carbon 1
This minor structural difference has major effect on biological roles as determines which bonds can be formed
Fructose properties
Very soluble and is main sugar in fruit
-pentose sugar
Galactose properties
Not as soluble as glucose but important in production of glycolipids and glycoproteins
Why are all monosaccharides reducing sugars
As they can donate electrons to other chemicals
How are disaccharides such as maltose formed
Condensation reaction between hydroxyl group on both alpha glucose to form 1-4 glycosidic bond and produce water
How can disaccharides be broken apart
Can be broken apart in a hydrolysis reaction requiring a molecule of water
What do alpha glucose monomers condense to form
Condense to form starch and glycogen
What do beta glucose molecules condense to form
Polymers of cellulose
What two polysaccharides does starch consist of
Amylose and amylopectin
Amylose properties
Unbranched polysaccharide made up of alpha glucose molecules joined together in a series of condensation reactions with 1-4 glycosidic bonds between them. It is unbranched so can coil up into helix held together by hydrogen bonds between hydroxyl groups on molecules
Amylopectin properties
Polysaccharide of alpha glucose molecules joined by 1-4 glycosidic bonds, branched every 15-20 molecules with chains joined by 1-6 glycosidic bonds.
Advantage of amylopectin being branched
As it is branched it has many ends for enzymes to break down the polysaccharide simultaneously and release glucose for respiration
Properties of starch and why these are important
-insoluble in water meaning it does not affect water potential so water is not drawn into cells by osmosis
-too large to pass across cell membrane
-compact so a lot can be stored in a small space
-when hydrolysed it forms alpha glucose which is easily transported for use in respiration
Glycogen properties
-similar structure to starch but has shorter chains and more highly branched due to more 1-6 glycosidic bonds along with 1-4 glycosidic bonds
-shorter chains means more branched ends for enzymes to work simultaneously to release glucose and as this is found in animal cells means can keep up with metabolic demand
-stored as small granules mainly in muscles and liver
what type of glucose is glycogen made up of
Alpha glucose
Monosaccharides maltose is made of
Two alpha glucose
Monosaccharides sucrose is made of
Fructose and glucose
Monosaccharides lactose is made of
Galactose and glucose
