carbohydrates Flashcards
what are some types of polymers ?
carbohydrates
proteins
nucleic acids
(not lipids)
define polymer
polymers are large, complex molecules composed of long chains of monomers joined together
define monomer
monomers are small basic molecular units
what are carbohydrates made from ?
monosaccharides and contain carbon, oxygen and hydrogen. C,H,O
give examples of monomers
. monosaccharides
. amino acids
. nucleotides
give the name of the three main monosaccharides
. glucose
. fructose
. galactose
what type of sugar is glucose?
a hexose sugar
what is a hexose sugar?
a monosaccharide with SIX carbon atoms
what are the two types of glucose?
alpha and beta
what are isomers?
molecules with same molecular formula but different molecular structure.
where is the hydroxyl OH placed in Beta glucose?
at the top
where is the hydroxyl OH placed in alpha glucose?
on the bottom
draw a beta and alpha glucose
look at page 2 of revision guide!
what is a condensation reaction ?
when two molecules join together to form a chemical bond and water is released.
monosaccharides are joined by condensation reactions, and glycosidic bond is formed.
how are disaccharides formed ?
. a disaccharide is formed when two monosaccharides join together.
how is the disaccharide maltose formed?
condensation reaction between glucose and glucose monosaccharides.
glucose + glucose—> =maltose + water
how is the disaccharide sucrose formed?
condensation reaction between glucose and fructose monosaccharides.
glucose + fructose—> sucrose + water
how is the disaccharide lactose formed?
condensation reaction between glucose and galactose monosaccharides.
glucose + galactose—> lactose + water
describe a hydrolysis reaction
polymers can be broken down by hydrolysis reactions.
a hydrolysis reaction breaks the chemical bond between monomers using WATER.
what is a general term for monosaccharides and disaccharides?
Sugar
what are the two types sugars
reducing e.g (all monosaccharides e.g glucose, fructose and galactose and most disaccharides such as maltose and lactose)
and non reducing e.g sucrose
describe how you would test for reducing sugars
1)add benedict’s blue reagent to sample( must be liquid if not grind up in water)
2) heat in a water bath that is boiled
3)positive result will show brick red or green, yellow for lower sugar
how can you compare the amount of reducing sugar in different solutions?
filter solution
weigh precipitate
describe test for non reducing sugars
1) get new sample of test solution( must be liquid if not grind up with water)
2)add dilute HCL (hydrochloric acid) and boil
3)neutralise with sodium hydrogen-carbonate because benedict’s doesn’t work in acidic conditions
4) retest with benedict’s and reheat in boiling water bath
5) positive will show orange brown, negative will show blue
describe the test for starch
1) add 2cm of sample being tested in test tube
2) 2 drops add iodine dissolved in potassium iodide solution
3) presence of starch yellow to blue- black
what are polysaccharides?
a polysaccharide is formed when more than two monosaccharides are joined together by a condensation reaction
what is between the monosaccharides boned together?
a glycosidic bond
where is starch found?
in plants, energy store of glucose
describe the monomers in starch
. alpha glucose
. amylose unbranched, helix/coiled up making it more compact for better storage as it fits more 1-4 glycosidic bonds
. amylopectin highly branched allowing better access for enzymes to break down molecule so glucose is released quickly with 1-4 and 1-6 glycosidic bonds
why is its structure suited for energy storage?
1) insoluble, doesn’t affect water potential, so water isn’t drawn out into cells by osmosis
2)helix in amylose 1-4 glycosidic bond makes it compact so it fits lots of glucose in small space
3)branched structure of amylopectin 1-4 & 1-6 glycosidic bond makes it highly branched increasing surface area for rapid hydrolysis into glucose
where is glycogen found? what is the role?
.animals and bacteria, never in plants.
.mainly found in muscles and liver.
energy store of glucose used in respiration
what is the monomer of glycogen ?
.alpha glucose
why is it suited for the role of storing glucose in animals?
.1 insoluble, doesn’t affect water potential, stops water from entering cells via osmosis
.2 insoluble, doesn’t diffuse out to cells
3. highly highly branched structure increases surface are for rapid hydrolysis into a glucose
where is cellulose found and what is its role?
. plant cell wall
. structural strength
what monomer is cellulose made form ?
beta glucose
describe the structure of cellulose
. long straight, unbranched chains.
.these chains are parallel to each other and linked with hydrogen bonds to form fibres called microfibrils.
.hydrogen bonds are individually weak but the amount of them make them collectively strong
why is cellulose suited to its function?
.insoluble, doesn’t affect water potential
.b glucose form long, straight, unbranched chains
.many hydrogen bonds in microfibrils provide collective strength
