carbohydrates Flashcards
What are monosaccharides
-Monosaccharides are the monomers from which larger carbohydrates are made. Glucose, galactose and fructose are common monosaccharides
What bond formed in a condensation reaction between 2 monosaccharides
-Glycosidic bond
How are disaccharides formed
-Condensation of 2 monosaccharides
Examples of disaccharides
-Sucrose, Maltose, Lactose
How is maltose formed
-Maltose is a disaccharide formed by condensation of two glucose molecules
How is sucrose formed
-Sucrose is a disaccharide formed by condensation of a glucose
molecule and a fructose molecule
How is lactose formed
-Lactose is a disaccharide formed by condensation of a glucose
molecule and a galactose molecule.
What is an isomer and give an example
-Isomers are compounds that have the same molecular formula but are structurally different
-Glucose has 2 isomers a and b
How are polysaccharides formed
-Polysaccharides are formed by the combination of a large number of monosaccharides through the glycosidic bond.
What are glycogen and starch made of
-Glycogen and starch are formed by the condensation of α-glucose.
What is cellulose made of
-Cellulose is formed by the condensation of β-glucose.
Structure of starch
-Mixture of two polysaccharides: amylose and amylopectin
-Amylose = long unbranched forms coiled/spring shape.
-Amylopectin = long branched chain due to 1-6 glycosidic bonds
Structure of glycogen
-A long, branched chain with lots of side branches (more than amylopectin). The glycosidic bonds are also 1-6.
Structure of cellulose
-Long unbranched straight chains. The glycosidic bonds are 1-4.
-The cellulose chains are then linked together by hydrogen bonds between the glucose molecules in each chain to form thicker fires called microfibrils.
Properties of starch
-Amylose = coiling makes it
compact and stores more in a smaller space
-Amylopectin = branches
increase surface area for enzymes to hydrolyse glycosidic bonds allowing glucose to be released quickly
Properties of glycogen
-Lots of branches increase surface area for enzymes to hydrolyse glycosidic bonds allowing glucose to be released quickly.
-It is also a compact molecule so it is good for storage.
Properties of cellulose
-The hydrogen bonds between the cellulose chains make the microfibrils very strong but still flexible allowing them to provide support.
Uses of starch
-Plants use starch as a way of storing excess glucose as it is too large to leave cells and insoluble (doesn’t dissolve in water - this also means it does not affect water potential).
-Starch can be hydrolysed to release glucose for respiration.
Uses of glycogen
-Animals store excess glucose as glycogen in muscles and in the liver.
-Glycogen is therefore an energy store as it can be hydrolysed to release glucose quickly when needed for respiration e. g during exercise.
Uses of cellulose
-Cellulose is a major structural component in the cell walls of plants, it provides support and allows cells to become turgid.
