2.7 - 2.14 Flashcards
what chemical elements are present in carbohydrates
CHO carbon, oxygen, hydrogen
what chemical elements are present in protein
CHON carbon, oxygen, hydrogen, nitrogen
what chemical elements are present in lipids
CHO carbon, hydrogen, oxygen
what are the monosaccharides of carbohydrates
simple sugars (glucose or fructose)
what is the disaccharide of carbohydrates
maltose (two glucose) and sucrose (one glucose one fructose)
what is a polysaccharide of carbohydrates
starch, glycogen, cellulose (formed when lots of molecules join together)
(they are insoluble therefore used as storage molecules)
what are most lipids in the body made up of
triglycerides
what are triglycerides
one glycerol molecule and three fatty acid chains
what are proteins formed from
amino acids (20 different types)
what are examples of proteins
enzymes, hemoglobin, ligaments, keratin
food test practical:
how to prepare a sample
- break up the food
- transfer to test tube and add distilled water
- mix the food in the water
- filter the mixture using a funnel and filter paper and collect the solution
- use the solution for the food tests
food test practical:
what is the test for glucose and how do you carry it out
the test is benedict’s solution
- you add the benedict’s solution to the sample in a test tube
- you heat it for 5 minutes
A positive test will be a color change from blue to to orange/brick red
food test practical:
what is the test for starch and how do you carry it out?
the test is iodine solution
- add drops of iodine solution to the sample in a test tube
A positive test will show a color change from orange to brown to blue black
food test practical:
what is the test for protein and how do you carry it out?
the test is biuret solution
- add drops of biuret solution to the sample in a test tube
A positive test will show a color change from blue to violet/purple
food test practical:
what is the test for lipids and how do you carry it out?
the test is ethanol
- add 4 cm^3 of ethanol to the sample in a test tube and shake
- once the sample dissolved in the ethanol, strain the ethanol solution in another test tube
- add the ethanol solution to 4cm^3 of cold distilled water
A positive test will show a cloudy emulsion
what is the role of enzymes in a chemical reaction
they work as biological catalysts to speed up the rate of reaction without being used up in the process
why are enzymes necessary
they maintain reaction speeds of all metabolic reactions (ex. digesting 1 meal would take 2-3 weeks to digest but with enzymes it only takes 4 hours)
what is it called when the enzyme and the substrate are grouped together
the enzyme substrate complex
what are factor that can affect enzyme action
temperature and pH
what is the optimum temperature in the human body for enzyme action
37°c
what happens to enzymes when it is above the optimum temperature
the bonds break and the enzyme is denatured
what happens when the enzymes are in a temperature under their optimum temperature
they work slower as there is less kinetic energy so the molecules move slower and therefore there is less collision between the enzyme and the substrates
enzyme activity practical:
what are we investigating
the effect on temperature on the activity of amylase which digests starch (which is a polysaccharide of glucose) into maltose (which is a disaccharide of glucose )
enzyme activity practical:
what is the method for this practical
- add 5 cm^3 of starch solution and heat to a certain temperature using a beaker of water with a bunsen burner
- add a drop of iodine to each of the wells of a spotting tile
- use a syringe to add 2cm^3 of amylase to the starch solution
- every minute transfer a droplet of the new solution to one of the spotting tiles.
- it should turn blue black
- repeat this until it does not turn blue black anymore
- this means the amylase has broken down all the starch
- record the time for the reaction to be completed (each tile is one min)
- repeat for a range of temps (20° to 60°)
enzyme activity practical:
what does the time mean depending on the temperatures
the faster it is, the faster the enzyme is working
what improvements could be made to this method
- use water baths for more precise temperatures
- a colorimeter can be used to measure the progress of the reaction more accurately
what is the optimum pH for most enzymes
pH of 7
what is the optimum pH for acidic conditions
pH of 2 for the stomach for example
what is the optimum pH for alkaline conditions
pH of 8 or 9 in the duodenum for example
what happens if the pH is too far from the optimum pH
the enzymes can denature
enzyme pH practical:
what is the enzyme that digests starch
amylase
enzyme activity practical:
what is the method for this practical
Amylase test
- add a drop of iodine to each well in a spotting tile
- use a syringe to place 2cm^3 of amylase into a test tube
- add 1cm^1 of buffer solution to the test tube
- use another test tube to add 2cm^3 of starch solution to the amylase and buffer solution.
- start the stopwatch
- every 10 seconds, transfer a droplet of the solution into one of the wells (should turn blue black)
- repeat until the iodine stops turning blue black
- record the time taken (each well is 10 seconds)
- repeat the investigation with buffers at different pH values (from 3-7)
enzyme activity practical:
what improvements can we make to this investigation
- the starch and amylase solution should be placed in a water bath at optimum temp. before being used
- a colorimeter can be used to measure the progress of the reaction more accurately.
