bbiioocchheemmiissttrryy...crash course the following is an investigation into the basic...

Biology 30S Name:

Digestion and Nutrition

Kelvin High School

The

BBiioocchheemmiissttrryy Crash Course

The following is an investigation into the basic biochemistry and identification of Carbohydrates, Proteins

and Fats. These groups of organic molecules are important to the normal function of the human body and

will be frequently encountered as we explore the Human Digestive System. Each section of this “Crash

Course” deals with one group of molecules. Read each section carefully and complete each of the

required tasks.

Section One: Carbohydrates

The Chemistry of Carbohydrates: Answer the following questions in the spaces provided. You may need to refer to your notes or

your text book in order to properly answer these questions

1. What is a Carbohydrate?

2. Define the following terms:

(a) Monosaccharide

(b) Disaccharide

(c) Polysaccharide

3. Identify the following molecules:

Biology 30S Name:


Kelvin High School

4. How do you draw the following:

Monosaccharide, Disaccharide, Polysaccharide

5. How is a Polysaccharide assembled from Monosaccharides?

The Task has been

completed satisfactorily

Biology 30S Name:


Kelvin High School

Identification of Carbohydrates:

Materials: Test tubes Test tube rack Grease pencil

Benedict’s Solution Iodine Solution Droppers

Hot Plate / Water Bath Beakers Test tube clamps

Monosaccharide Solution Disaccharide Solution Polysaccharide Solution

Apple juice Oat solution Table sugar solution

Honey solution Powdered Sugar solution

Procedure #1: Testing Known Carbohydrates

Benedict’s Test:

1. Prepare a hot water bath (your teacher will do this for you)

2. Get three test tubes and number them one to three using a grease pencil

3. Using a clean dropper for each tube, add the following:

Tube #1 – 30 drops of monosaccharide solution

Tube #2 – 30 drops of disaccharide solution

Tube #3 – 30 drops of polysaccharide solution

4. Add 30 drops of Benedict’s Solution to each tube. Use the diagram below as a guide:

.

5. Observe the tubes and record your observations in the table below.

6. Place the three test tubes into a hot water bath for five minutes

7. Use a test tube clamp to remove the tubes from the hot water bath

8. Observe the tubes again and record your observations in the table below.

Table #1: Benedict’s Test With Known Carbohydrates

Tube

Number

Carbohydrate

Type

Benedict’s Colour Before

Heating

Benedict’s Colour After

Heating

#1 Monosaccharide Blue Orange #2 Disaccharide Blue Blue #3 Polysaccharide Blue Blue

Biology 30S Name:


Kelvin High School

Iodine Test: 1. Get three cleans and number them one to three using a grease pencil.

2. Using a clean dropper for each tube, add the following:

Tube #1 – 30 drops of Monosaccharide Solution

Tube #2 – 30 drops of Disaccharide Solution

Tube #3 – 30 drops of Polysaccharide Solution

3. Observe the test tubes and record your results in the table below.

4. Add 4 drops of Iodine Solution to each tube. Use the diagram below as a guide:

5. Mix the contents of each tube by gently swirling the test tube

6. Observe the test tubes and record your results in the table below.

Table #2: Iodine Test With Known Carbohydrates

Tube

Number

Carbohydrate

Type

Carbohydrate Colour

Before Adding Iodine

Carbohydrate Colour

After Adding Iodine

#1 Monosaccharide Pale yellow Pale yellow

#2 Disaccharide Pale yellow Pale yellow

#3 Polysaccharide Pale yellow Dark Blue

The Task has been


Biology 30S Name:


Kelvin High School

Procedure #2: Testing Unknown Carbohydrates

By comparing the results of this procedure with the Benedict’s and Iodine test results completed

in the previous section, you should be able to identify some unknown carbohydrates as a

monosaccharide, disaccharide, or polysaccharide.

1. Get 5 clean test tubes and number them one to five with a grease pencil

2. Using a clean dropper, add the following to each tube:

Tube #1 – 20 drops of Honey Solution

Tube #2 – 20 drops of Liquid Oats

Tube #3 – 20 drops of Table Sugar Solution

Tube #4 – 20 drops of Apple Juice

Tube #5 – 20 drops of Powdered Sugar Solution

3. Add 30 drops of Benedict’s Solution to each test tube. Use the diagram below as a guide:

4. Place all five test tubes into a hot water bath for five minutes

5. Remove the test tubes from the bath using a test tube clamp

6. Observe the tubes and record your observations in the Benedict’s Test column of Table #3

7. Get 5 more clean test tubes and label them one to five with a grease pencil

8. Using a clean dropper for each tube, add the following to each tube:

Tube #1 – 20 drops of Honey Solution

Tube #2 – 20 drops of Liquid Oats

Tube #3 – 20 drops of Table Sugar Solution

Tube #4 – 20 drops of Apple Juice

Tube #5 – 20 drops of Powdered Sugar Solution

Biology 30S Name:


Kelvin High School

9. Add 4 drops of Iodine Solution to each tube and mix by swirling. Use the following diagram

as a guide:

10. Observe the tubes and record your results in the Iodine Test Results column of Table #3

11. Based on the results of both tests, classify each carbohydrate as a monosaccharide,

disaccharide or polysaccharide and record your answers in Table #3

Table #3: Results of Tests With Unknown Carbohydrates

Carbohydrate Benedict’s Test Results Iodine Test Results Type of Carbohydrate

Honey orange Pale yellow

Oats blue Dark blue

Table Sugar blue Pale yellow

Apple Juice orange Pale yellow

Powdered Sugar blue Pale yellow

The Task has been


Biology 30S Name:


Kelvin High School

Section Two: Proteins

The Chemistry of Proteins: Answer the following questions in the spaces provided. You may need to refer to your notes or


1. What is a Protein?


(a) Amino Acid

(b) Monopeptide

(c) Polypeptide


Monopeptide, Polypeptide

Biology 30S Name:


Kelvin High School

4. How is a Polypeptide assembled from Monopeptides?

The Task has been


Biology 30S Name:


Kelvin High School

Identification of Proteins:

Materials:

Droppers test tubes test tube racks

Ceramic Spot Plate Nitric Acid Biuret’s Reagent

Grease pencils fingernail clippings egg white (hard boiled)

Absorbent cotton dog hair cream cheese

Procedure #3: Xanthoproteic Test

The Xanthoproteic Test is used to identify Proteins. The term Xanthoproteic is Latin in origin and is

derived from the words “xantho” (which means yellow) and “proteic” (which means protein). If a

substance turns yellow during this test it is a protein.

1. Get a clean Ceramic Spot Plate

2. Using the diagram below as a guide, add a small amount of each of the following substances

to a separate well on the spot tray

Well #1 – fingernail clippings

Well #2 – egg white (hard boiled)

Well #3 – absorbent cotton

Well #4 – dog hair

Well #5 – cream cheese

3. Add 5 drops of Nitric Acid to each well

4. Wait for 30 seconds and then observe the wells and record your results in the Xanthoproteic

Test Results column of Table #4

Well #1

Fingernail

clippings

Well #2

Egg White Well #3

Cotton

Well #4

Dog Hair

Well #5

Cream

Cheese

Biology 30S Name:


Kelvin High School

Procedure #4: Biuret’s Test The Biuret’s Test is another test use to identify proteins. Biuret’s reagent will react with protein

molecules after a short period of time. (Will eventually turn Purple)

1. Get a clean Ceramic Spot Plate

2. Using the diagram below as a guide, add a small amount of each of the following substances

to a separate well on the spot tray

Well #1 – fingernail clippings

Well #2 – egg white (hard boiled)

Well #3 – absorbent cotton

Well #4 – dog hair

Well #5 – cream cheese

3. Add 5 drops of Biuret’s Reagent to each well

4. Wait for 5 minutes and then observe the wells and record your results in the Biuret’s Test

Results column of Table #4

Table #4: Identifying Proteins

Substance Xanthroproteic

Test Results

Biuret’s

Test Results

Is the Substance

a Protein?

(Yes or No)

Fingernail Turns yellow Turns Purple

Egg White Turns yellow Turns Purple

Cotton No change No change

Dog Hair Turns yellow Hard to tell

Cream Cheese Turns Yellow Turns Purple

The Task has been


Well #1

Fingernail

clippings

Well #2

Egg White Well #3

Cotton

Well #4

Dog Hair

Well #5

Cream Cheese

Biology 30S Name:


Kelvin High School

Section Three: Lipids and Fats

The Chemistry of Lipids and Fats: Answer the following questions in the spaces provided. You may need to refer to your notes or


1. What is a Lipid?

2. What is a Fat?


(a) Fatty Acid

(b) Glycerol

(c) Monoglyceride

(d) Triglyceride

(e) Saturated Fat

(f) Unsaturated Fat

4. What is a unique characteristic of Fat Polymers that are not shared by other Polymers?

Biology 30S Name:


Kelvin High School


Fatty Acid, Glycerol, Triglyceride

6. How is a Triglyceride assembled from Glycerol and Fatty Acids?

The Task has been


Biology 30S Name:


Kelvin High School

Identification of Fats (Lipids):

Materials:

Grease pencils Test tubes test tube rack

Eye dropper distilled water brown paper

Lighter fluid oil (canola, olive) test tube stoppers

Unknown Substances X,Y and Z

Procedure #5: Solubility Test on Known Fats

Generally speaking, Fats (lipids) tend to be oils or semi solids. Fats are useful in that they can

store energy and some vitamins and nutrients. An object is considered soluble in water if it

completely disappears or is evenly mixed when added to water. An object is considered

insoluble in water if it is unable to mix with water when it is added. The following is a solubility

test of a known fat – oil.

1. Get two clean test tubes and label them one and two with a grease pencil

2. Add 10 drops of oil to each tube

3. Add 20 drops of lighter fluid to tube #1

4. Add 20 drops of cold water to tube #2. Use the diagram below as a guide:

5. Place a stopper on the end of each tube. Place your thumb over the stopper and shake

each tube for one minute

6. Wait one minute

7. Examine and compare both tubes. Record your results in Table #5

Biology 30S Name:


Kelvin High School

Procedure #6: Brown Paper Test for Fats

This is another easy test used to identify Fats. An interesting thing happens when fats are rubbed

against brown paper.

1. On separate pieces of brown paper, rub one drop of oil (a fat) and one drop of water (not a

fat)

2. Allow the paper to dry for a few minutes

3. Hold the paper toward light. If light passes through, a translucent (semitransparent) spot

has formed.

4. Examine the pieces of paper to check for a translucent spot. Record your results in Table #5

Table #5: Results of Tests on Known Fats

Test Results

Fat Mixed with Lighter Fluid Soluble

Fat mixed with Cold Water Insoluble

Fat Rubbed on Brown Paper Forms clear spot

Water Rubbed on Brown Paper No noticeable change

The Task has been


Biology 30S Name:


Kelvin High School

Procedure #7: Testing Unknown Substances for Fats

1. Get three clean test tubes and label them X, Y and Z with a grease pencil

2. Place a SMALL amount of Unknown Substance X into the tube labelled X

3. Place a SMALL amount of Unknown Substance Y into the tube labelled Y

4. Place a SMALL amount of Unknown Substance Z into the tube labelled Z

5. Add 20 drops of water to each tube

6. Cover each tube with a stopper. Place your thumb on the stopper and shake each tube for

one minute.

7. Examine the tubes and record your results in Table #6

8. Repeat steps #1 - #4 9. Add 20 drops of lighter fluid to each tube

10. Cover each tube with a stopper. Place your thumb on the stopper and shake each tube for

one minute.

11. Examine the tubes and record your results in Table #6

Table #6: Testing Unknown Substances for Fat

Substance Soluble in

Water

Soluble in

Lighter Fluid

Translucent Spot

Formed on

Brown Paper

Fat Present?

X yes

yes

yes

Y no

yes

yes

Z no

no

sort of

The Task has been


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