Lab 2A - Identifying Biological Molecules PDF

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Summary

Lab 2A - Identifying Biological Molecules...

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Lab 2A - Identifying Biological Molecules Purpose: A variety of tests to determine the presence of proteins, carbohydrates, and lipids. Materials - Water - Food Samples - Test Tubes - Test Tube Rack - 250mL Beaker - Hot plate

- Rubber Gloves - Brown Paper Bag - Benedict’s Solution - Biuret’s Solution - Lugol’s Solution (Iodine) - Mortar and Pestle

Procedure: Refer to pages 46-47, in BC Biology 12 textbook. Data/Observation:

Part 1: Benedict Solution Test for Simple Sugars

Test Tube

Test Sample

Observations for Simple Sugars Test

Presence Of Sugars

1

Water

Transparent baby blue

No

2

Cereal

Transparent blue with cheerio bits

No

3

Potato

Opaque breen

No

4

Corn Syrup

Opaque orange/red colour

Yes

5

Cooked Pasta

Opaque green

No

6

Unknown Sample

Transparent with bits of sample floating

No

Part 2: Lugol’s Solution Test For Starch Test Tube

Test Sample

Observations for Starch Test

Presence of Starch

1

Water

Ochre colour

No

2

Potato

Dark green

Yes

3

Bread

Dark purple with sponge like material

Yes

4

Apple

Dark yellow

No

5

Crackers

Dark purple with white chunks

Yes

6

Cooked pasta

Dark purple with pasta bits

Yes

7

Unknown Sample

Opaque dark purple

Yes

Part 3: Biuret Solution Test For Proteins Test Tube

Test Sample

Observation For Lipids Test

Presence of Lipids

1

Water

Left a wet spot and then dried up

No

2

Oil

Translucent when held to light

Yes

3

Milk

Translucent when held to light

Yes

4

Tofu

Translucent when held to light

Yes

5

Meat

Translucent when held to light

Yes

6

Yogurt

Left no grease spots

No

7

Unknown Sample

Left no grease spots

No

Part 4: Biuret Solution Test For Proteins Test Tube

Test Sample

Observation For Protein Test

Presence of Protein

1

Water

Transparent baby blue colour

No

2

Egg

Opaque orchid colour

Yes

3

Milk

Opaque Lavender colour

Yes

4

Tofu

Opaque dark purple with tofu bits

Yes

5

Meat

Transparent blue and chicken turns purple

Yes

6

Yogurt

Opaque Lavender Colour

Yes

7

Cheese

Opaque dark purple with cheese clumps

Yes

8

Unknown Sample

Opaque Purple

Yes

Results/Discussion:

1) The Polymers that were in the food samples were simple sugars, lipids, and proteins. Simple sugars and starch are both classified as carbohydrates, These monomers that make up these polymers are monosaccharides, glycerol, and fatty acids which makes up lipids. Lipids are proteins are polymers composed of amino acid monomers

2) Refer to the next page for question #2.

3) The control variable strongly influences the experimental results, and it is held constant during the experiment in order to test the relative relationship between the dependant and independent variables. The control variable itself is not of any actual interest to the experimenter.

2) Molecule

Simple Sugar

Starch

Fats

Protein

Function

Food Source

Name Of Chemical Test

-Changes into glucose to be used for energy or later use

-Water -Corn Syrup -Unknown sample -Cooked pasta -Cereal

Benedict's Solution

-changes into glucose to provide energy to the body

-Long term energy storage -Forms a protective cushion around major organs -Insulates against heat loss

-Makes up hair, nails, and collagens -Enzymes are necessary for chemical workings of a cell -Actin and myosin account for movement of cells and the ability of our muscles to contract

-Water -Potato -Bread -Apple -Crackers -Cooked Pasta - Unknown Sample

-Water -Oil -Lard -Chips -Butter -Sesame Seeds -Unknown Sample

-Egg -Milk -Cheese -Tofu -Water -Meat -Unknown Sample

Lugol’s Solution

Biuret Solution

Negative Test Results

-Water -Cereal -Potato -Cooked Pasta

-Water -Apple

-Water

-Water

Positive Test Results

-Corn Syrup

-Potato -Bread -Crackers -Cooked Pasta

-Oil -Lard -Chips -Butter

-Milk -Egg -Tofu -Meat

-Yogurt -Cheese...