2- biological molecules Flashcards
chemical elements in a carbohydrate
carbon, oxygen, hydrogen
chemical elements in a protein
all contain carbon, oxygen, hydrogen and nitrogen
some contain small amounts of other elements
chemical elements in an lipid
carbon, oxygen and hydrogen
most fats are made up of
triglycerides
fats basic unit is
one glycerol molecule chemically bonded to three fatty acid chains
fatty acids vary in
size and structure
lipids are divided into
fats and oils
proteins are formed from
long chains of amino acids
proteins shape
different proteins have different amino acid sequences resulting in them being different shapes
test for glucose
Benedict’s solution:
-heat in water bath in a test tube for 5 mins
positive test will show colour change from blue-orange/brick red
test for starch
iodine;
-add drops of iodine to food sample
positive test shows colour change from orange/brown-blue/black
test for protein
biuret solution;
-add drops of buret solution to food sample
positive test shows colour change blue-violet/purple
test for lipids
-mix food sample with 4cm3 of ethanol and shake
-allow time for sample to dissolve
-strain the ethanol solution into another test tube
-add ethanol solution to equal volume of cold distilled water
positive test will show cloudy emulsion forming
enzymes are proteins that act as
biological catalysts to speed up the rate of a chemical reaction without being changed or used up in the reaction
enzymes are necessary to all living organisms because
they maintain reaction speeds of all metabolic reactions at a rate that can sustain life
enzymes are specific to one particular substrate as
the active site of an enzyme, where the substrate attaches, is complementary to the substratee
when the substrate moves into the enzymes active site they become known as
the enzyme-substrate complex
after the reaction has occurred the product leaves the enzymes active site because
they no longer fit and it is free to take up another substrate
enzymes work best at their
optimum temperature
denatured enzymes
when high temperatures break the bonds that hold the enzyme together and it will lose its shape
denaturartion is
irreversible as once the enzymes have denatured they can’t regain their proper shape and the activity will stop
increasing temperature affect on enzymes
increrasing temperature towards the optimum increases the activity of enzymes as the more kinetic energy the molecules have the faster they move and the number of collisions with the sub state increases, which increases the rate of reaction
low temperature affect on enzymes
doesn’t denature the enzymes but makes them work more slow due to lack off kinetic energy
optimum pH for most enzymes is
7
pH is too high or low affect on enzymes
the bonds that hold the amino acid chain together to make up the protein can be destroyed, this changes the shape of the active site so the substrate can no longer fit into it reducing the rate of activity
amylase is
an enzyme that digests starch into maltose
apparatus needed to investigate the affect of temperature on the activity of amylase (temperature affect on enzymes)
spotting tile, measuring cylinder, test tube, syringe, pipette, stopwatch, water, thermometer, water bath, iodine, starch solution, amylase solution
method to investigate the affect of temperature on the activity of amylase (temperature affect on enzymes)
1) add 5cm3 of starch to a test tube and heat to a set temperature
2) add a drop of iodine to each of the wells of a spotting tile
3) use a syringe to add 2cm3 of amylase to the starch solution and mix well
4) every minute transfer a droplet of solution to a new well of iodine solution (which should turn blue/black)
5) repeat this until iodine stops turning blue/black (this means amylase has broken down all the starch)
6) record the time taken for the reaction to be completed
7) repeat investigation for a range of temperatures (from 20 degrees to 60)
results of experiment to investigate the affect of temperature on the activity of amylase (temperature affect on enzymes)
the investigation shows that at the optimum temperature the iodine stopped turning blue/black the fastest because the enzyme is working at the fastest rate and has digested all the starch. at colder temperatures the iodine took longer to stop turning blue/black because the amylase enzyme is working slower due to low kinetic energy and fewer collisions. at higher temperatures (above optimum) the iodine turned blue/black the whole investigation because the enzyme has become denatured and can no longer bind with the starch or break down
apparatus needed to investigate the affect of pH on the activity of amylase (pH affect on enzymes)
spotting tile, measuring cylinder, test tube, syringe, pipette, stopwatch, buffer solutions, iodine, starch solution, amylase solution
method to investigate the affect of pH on the activity of amylase (pH affect on enzymes)
1) add a drop of iodine to each of the wells of a spotting tile
2) use a syringe to place 2cm3 of amylase and 1cm3 of buffer solution (at pH 2) to the test tube
3) use another test tube to add 2cm3 of starch solution to the the amylase and buffer solution and start the stopwatch whilst mixing using a pipette
4) every 10 seconds transfer a droplet of the solution to a new well of iodine solution (which should turn blue/black)
5) repeat this transfer process every 10 seconds until the iodine solution stops turning blue-black (this means amylase has broken down all the starch)
6) record the time taken for the reaction to be completed
7) repeat the investigation with buffers at different pH values (ranging from pH 3.0 to pH 7.0)
results of experiment to investigate the affect of pH on the activity of amylase (pH affect on enzymes)
at the optimum pH, the iodine stopped turning blue/black and remained orange/brown within the shortest amount of time because the enzymes is working at its fastest rate and has digested all the starch. at higher/ lower pH (above or below the optimum) the iodine took longer to stop turning blue/black because at either side of the optimum pH the enzymes are started to become denatured and as a result are unable to bind with the starch or break it down.
