monomers, polymers and monosaccahrides Flashcards
definition of monomer
the smaller units from which larger molecules are made
definition of a polymer
molecules made from a large number of monomers joined together
three examples of monomers
monosaccharides
amino acids
nucleotides
what is a condensation reaction
a reaction that joins two molecules together
with the formation of a chemical bond
and involves the elimination of a molecule of water
what is a hydrolysis reaction
a reaction that separates molecules
by breaking a chemical bond
and involves the use of a water molecule
give the definition of a monosaccharide
the monomers from which larger carbohydrates are made
name three common monosaccharides
glucose
galactose
fructose
name the isomers of glucose
alpha-glucose and beta-glucose
describe how disaccharides are formed
by a condensation reaction between two monosaccharides
write the word equation for the formation of each disaccharide
glucose + glucose = maltose + water
glucose + fructose = sucrose + water
glucose + galactose = lactose + water
describe the test for reducing sugars
add benedict’s reagent
heat
a positive result is a colour change from blue to green/yellow/orange/red
suggest why the colour change occurs at the top of the test tube first
heat rises (convection currents)
the reaction occurs at the top of the test tube first
describe the test for non-reducing sugars
following a negative reducing sugars test
boil the sample in acid (acid hydrolysis) - then add alkaline solution to neutralise
add benedict’s reagent and head
a positive result will go from blue to orange / red
describe the test for starch
add iodine to the sample
a positive result will go from orange to blue / black
describe the test for lipids
add ethanol and shake to dissolve
then add distilled water
a positive result is a white emulsion
describe the test for proteins
add biuret reagent to the sample
a positive result will go from blue to purple
starch - monomers
alpha glucose
starch - which reaction and bonds join the monomers together
condensation
1,4 and 1,6 glycosidic bonds
starch - state the function of the molecule
glucose store (energy source)
starch - state where the molecule is found
starch grains in plant cells
describe the structure of starch
starch is made up of amylose and amylopectin
amylose monomers are joined by 1,4 glycosidic bonds resulting in a spiral-shaped polymer
amylopectin monomers are joined by 1,4 and 1,6 glycosidic bonds
the 1,6 glycosidic bonds result in branches
explain how the structure of starch related to function
starch is insoluble due to the fact is it a large molecule
it will not change the water potential of a cell and cause osmosis to occur
the spiral shape means that it can be readily compacted to store a lot
the branching strands provide a large surface area for enzymes to attach to increase hydrolysis
name the monomers of glycogen
alpha glucose
which reaction and bonds join the monomers of glycogen together
consensation
1,4 and 1,6 glycosidic bonds
state the function of glycogen
glucose store - energy source
describe the structure of glycogen
the key difference between the structure of glycogen and starch is that glycogen contains more 1,6 glycosidic bonds and is therefore more branched
