carbohydrates Flashcards
how are disaccharides formed?
two monosaccharides join through a condensation reaction, releasing water and forming a glycosidic bond
which two monosaccharides make the disaccharide maltose?
glucose and glucose
which two monosaccharides make the disaccharide sucrose?
glucose and fructose
which two monosaccharides make the disaccharide lactose?
glucose and galactose
what are the two isomers of glucose?
alpha and beta
name the three carbohydrates?
starch
glycogen
cellulose
which carbohydrates are alpha and which are beta?
starch and glycogen are alpha glucose.
cellulose is beta glucose.
name a difference between alpha and beta glucose.
beta glucose has an inverted hydroxyl group.
what are the two types of starch?
amylopectin and amylose
which carbohydrates are branched and which are unbranched?
branched - glycogen, amylopectin
unbranched - amylose, cellulose
what is the bond formed between monosaccharides?
glycosidic bond
how are polysaccharides formed?
many monosaccharides join through a condensation reaction, releasing water and forming a glycosidic bond.
describe the structure and function of starch.
- for energy store in plant cells
- its a polysaccharide of a-glucose
- has 1,4 glycosidic bonds and is unbranched
describe the structure and function of glycogen.
- for energy store in animal cells
- its a polysaccharide of a-glucose
- has 1,4 and 1,6 glycosidic bonds and is branched.
explain how the structures of starch relates to its function.
its helical which makes it compact for storage in the cell.
its a large polysaccharide molecule so it cant leave the cell.
its insoluble in water so it doesn’t affect cell water potential.
explain how the structure of glycogen relates to its function.
its branched which means it has more ends for faster hydrolysis to release glucose for respiration to make ATP for energy release.
its a large polysaccharide molecule so it cant leave the cell.
its insoluble in water so it doesn’t affect cell water potential.
describe the structure and function of cellulose.
- provides strength and structural support to plant cell walls.
- its a polysaccharide of b-glucose
- has 1,4 glycosidic bonds so forms straight unbranched chains.
- chains are linked in parallel by hydrogen bonds, forming microfibrils
explain how the structure of cellulose relates to its function.
b-glucose has inverted hydroxyl groups in a long straight unbranched chain.
many hydrogen bonds link parallel strands to form microfibrils.
has high number of strong hydrogen bonds which provides strength to plant cell walls.
describe the test for reducing sugars.
add Benedict’s solution, then heat, and it will turn red if positive.
give examples of reducing sugars.
monosachharides, maltose, lactose
give an example of a non reducing sugar.
sucrose
describe the test for non reducing sugars.
hydrolyse a disaccharide using an acid, neutralise with alkali, then carry out Benedict’s test, it will turn red if positive.
suggest a method to measure the quantity of sugar in a solution.
carry out Benedict’s test, then filter and dry the precipitate - find mass.
describe the test for starch.
add iodine dissolved in potassium iodide and shake, positive result would be blue-black.
