Carbohydrate,
Lipid, & Protein
Identification Lab
BENEDICT’S TEST
Solution
Water
Glucose
Fructose
Maltose
Lactose
Sucrose
Starch
Initial
Blue
Blue
Blue
Blue
Blue
Blue
Blue
Final
Blue
Orange
Orange
Orange
Orange
Blue
Blue
% Sugar
Negative
5%
5%
5%
5%
Negative
Negative
IODINE TEST
Solution
Water
Glucose
Fructose
Maltose
Lactose
Sucrose
Starch
Initial
Yellow/Brown
Yellow/Brown
Yellow/Brown
Yellow/Brown
Yellow/Brown
Yellow/Brown
Yellow/Brown
Final
Yellow/Brown
Yellow/Brown
Yellow/Brown
Yellow/Brown
Yellow/Brown
Yellow/Brown
Blue/Black
TRANSLUCENCE TEST
Solution
Water
Oil
Final
Not translucent
Translucent
BIURET TEST
Solution
Water
Gelatin (protein)
Initial
Blue
Blue
Final
Blue
Purple
CONCLUSIONS
1. Why should graduated cylinders and droppers be cleaned after each usage?
This is to avoid contamination of samples.
2. Which test tube served as a control in the test for reducing sugars and starches
(Part 1+2)? Why are controls used in the experiments?
Water is used as a control because it is negative in all tests and
a medium for all reactions. Controls are used to be sure that
what we are testing (manipulated variable) is what causes
changes (responding variables) and NOT side reactions.
3. What laboratory data suggests that not all sugars are reducing sugars?
Reducing sugars are (generally) simple sugars or monosaccharides
(Benedict’s). Starch (polysaccharide) is NOT a sugar and sucrose
(disaccharide) is not reducing so it is negative in Benedict’s test.
CONCLUSIONS
4. A student decides to sabotage the lab results of his classmates and places a sugar
cube into solution Z. Explain the effect of dissolving a sugar cube in the solution.
Sugar is sucrose. Sucrose tested negative with Benedict’s AND with
iodine (both carbohydrate tests) so there would be no harm done.
5. A drop of iodine accidentally falls on a piece of paper. Predict the colour
change, if any, and provide an explanation for your prediction.
Paper turns blue/black with iodine. This shows that it contains
starch. This makes sense since plants store their glucose
(produced during photosynthesis) as polysaccharide (starch).
6. A student heats a test tube containing a large amount of protein and notices a
colour change in the test tube. Explain why heating causes a colour change.
Heating causes a re-arrangement of peptide bonds which is a
chemical change. Colour change indicates chemical change.
CONCLUSIONS
7. Explain the advantage of using two separate tests for fats.
Having extra tests would confirm results.
8. Would you expect to find starches and sugars in blood plasma? Explain your
answer.
There should be sugars (monosaccharides) in the blood since
all cells require sugars for energy and monosaccharides are the
breakdown products of carbohydrate digestion. There would
NOT be starches, however, because starch is a big molecule
(polysaccharide) and could not diffuse from the intestine into
the blood without first being broken down into simple sugars.
Enzyme Lab
RESULTS:
TUBE #
REACTION RATE
PRODUCT OF
REACTION
1
(SAND)
0
NO REACTION
O2
2
(POTATO)
1
SLIGHT REACTION
O2
3
(LIVER)
3
GOOD REACTION
O2
4
4
VERY VIGOROUS
O2
(CRUSHED
LIVER)
Enzyme Activity (Arbitrary Units)
Effect of pH on Enzyme Activity
3.5
3
2.5
2
Activity Enzyme X
(Arbitrary Units)
1.5
Activity Enzyme Y
(Arbitrary Units)
1
0.5
0
0
5
10
pH
15
Enzyme Activity (Arbitrary Units)
Effect of Temperature on Enzyme Activity
12
10
8
6
Activity Enzyme X
(Arbitrary Units)
4
Activity Enzyme Y
(Arbitrary Units)
2
0
-2
0
20
40
Temperature (oC)
60
RESULTS
1. In part 1, which test served as the control. Why was it needed?
The tube with the sand served as the control. This was needed to
show that peroxide has NO CHEMICAL REACTION WITH
SAND. Thus, any subsequent reaction is due to enzymes in liver
(or potato).
2. Account for the different reaction rates between the liver and potato.
Liver contains the enzyme catalase which breaks down hydrogen
peroxide (H2O2) into water and oxygen. There is little catalase in
potatoes (which grow underground) (low O2).
3. Why did the crushed liver in #4 react differently from the uncrushed
liver in #3?
Crushing liver exposes more catalase to the substrate so produces
a faster reaction (increased surface area exposed).
RESULTS
4. Would the rate of reaction be faster or slower with more enzyme?
Would the amount of product be more or less? Explain.
NORMAL REACTION: TIME = 0 seconds
RESULTS
4. Would the rate of reaction be faster or slower with more enzyme?
Would the amount of product be more or less? Explain.
NORMAL REACTION: TIME = 1 second
RESULTS
4. Would the rate of reaction be faster or slower with more enzyme?
Would the amount of product be more or less? Explain.
NORMAL REACTION: TIME = 2 seconds
RESULTS
4. Would the rate of reaction be faster or slower with more enzyme?
Would the amount of product be more or less? Explain.
NORMAL REACTION: TIME = 3 seconds
PRODUCT = 3 O2 IN 3 seconds (1 mol/sec)
RESULTS
4. Would the rate of reaction be faster or slower with more enzyme?
Would the amount of product be more or less? Explain.
3x ENZYME: TIME = 0 seconds
RESULTS
4. Would the rate of reaction be faster or slower with more enzyme?
Would the amount of product be more or less? Explain.
3x ENZYME: TIME = 1 second
PRODUCT = 3 O2 IN 1 second (3 mol/sec)
RESULTS
4. Would the rate of reaction be faster or slower with more enzyme?
Would the amount of product be more or less? Explain.
Having more enzyme speeds up reaction rate but amount of
product is the same if amount of substrate does not change.
RESULTS
5. Would the rate of reaction be faster or slower with more
substrate? Would the amount of product be more or less? Explain.
NORMAL REACTION: TIME = 0 seconds
RESULTS
5. Would the rate of reaction be faster or slower with more
substrate? Would the amount of product be more or less? Explain.
NORMAL REACTION: TIME = 1 second
RESULTS
5. Would the rate of reaction be faster or slower with more
substrate? Would the amount of product be more or less? Explain.
NORMAL REACTION: TIME = 2 seconds
RESULTS
5. Would the rate of reaction be faster or slower with more
substrate? Would the amount of product be more or less? Explain.
NORMAL REACTION: TIME = 3 seconds
PRODUCT = 3 O2 IN 3 seconds (1 mol/sec)
RESULTS
5. Would the rate of reaction be faster or slower with more
substrate? Would the amount of product be more or less? Explain.
2X SUBSTRATE: TIME = 0 seconds
RESULTS
5. Would the rate of reaction be faster or slower with more
substrate? Would the amount of product be more or less? Explain.
2X SUBSTRATE : TIME = 1 second
RESULTS
5. Would the rate of reaction be faster or slower with more
substrate? Would the amount of product be more or less? Explain.
2X SUBSTRATE : TIME = 2 seconds
RESULTS
5. Would the rate of reaction be faster or slower with more
substrate? Would the amount of product be more or less? Explain.
2X SUBSTRATE : TIME = 3 seconds
RESULTS
5. Would the rate of reaction be faster or slower with more
substrate? Would the amount of product be more or less? Explain.
2X SUBSTRATE : TIME = 4 seconds
RESULTS
5. Would the rate of reaction be faster or slower with more
substrate? Would the amount of product be more or less? Explain.
2X SUBSTRATE : TIME = 5 seconds
RESULTS
5. Would the rate of reaction be faster or slower with more
substrate? Would the amount of product be more or less? Explain.
2X SUBSTRATE : TIME = 6 seconds
PRODUCT = 6 O2 IN 6 seconds (1 mol/sec)
RESULTS
5. Would the rate of reaction be faster or slower with more
substrate? Would the amount of product be more or less? Explain.
Having more substrate would not affect the reaction RATE
(although the total reaction TIME would be longer). The amount
of PRODUCT is proportional to the SUBSTRATE put in so
would increase with increased substrate.
6. Does changing the pH of an enzyme change the results? What
happens to the enzymes in high and low pH? Relate these findings
to conditions in the body.
Yes, enzymes work best at certain pH levels. At extreme pH (high
or low) enzymes “denature” and function poorly. In the body
there are different places with different pHs. Ex. A stomach
enzyme should work BEST at LOW pH while a blood enzyme
might work best at slightly higher than pH 7.
RESULTS
7. What would be the optimal pH for an organ secreting BOTH
types of enzyme in the graphed data?
Optimal pH for BOTH enzymes would be pH 5.5.
Enzyme Activity (Arbitrary Units)
Effect of pH on Enzyme Activity
3.5
3
2.5
2
Activity Enzyme X
(Arbitrary Units)
1.5
Activity Enzyme Y
(Arbitrary Units)
1
0.5
0
0
5
10
pH
15
RESULTS
8. Does changing the temperature of an enzyme change the results?
What happens to the enzymes in high and low temperature? Relate
these findings to conditions in the body.
Yes, enzymes work best at certain temperature levels. At extreme
temperature enzymes function poorly. Heat “denatures” or melts
proteins essentially destroying them. Cold slows/freezes the
active site. It doesn’t work but CAN recover if thawed out. In the
body there are different places with different temperatures.
Ex. A muscle enzyme might work at elevated temperatures.
Enzymes making sperm require lower than body temperatures (so
testes are held outside the body).
RESULTS
9. What would be the optimal temperature for an organ secreting
BOTH types of enzyme in the graphed data?
Optimal temperature for BOTH enzymes would be 23ºC.
Enzyme Activity (Arbitrary Units)
Effect of Temperature on Enzyme Activity
12
10
8
6
Activity Enzyme X
(Arbitrary Units)
4
Activity Enzyme Y
(Arbitrary Units)
2
0
-2
0
20
40
Temperature (oC)
60
RESULTS
10. Give some reasons you can think of for why different enzymes
might react differently in different conditions (amount, pH,
temperature).
Enzymes in different organisms or different parts of the same
organism may be exposed to varying pH ranges, temperatures,
and substrate concentrations. Body conditions vary as do
environments in which an organism lives.
Ie. Arctic waters, tropical deserts, volcanic vents, stomach acids,
etc.