Warm Up• How many

total carbohydrates can be found in 1 bag of chips?

Testing for the Presence of

MACROMOLECULES

Let’s Review• Carbohydrates, proteins,

and fats are all essential nutrients.

• We cannot manufacture these nutrients so we must obtain them from our environment.

What is an indicator?

• Indicators are chemical compounds used to detect the presence of other compounds.

Background InformationINDICATOR MACRO-

MOLECULENEGATIVE

TESTPOSITIVE

TEST

Benedict’s solution

simple carbohydrate

blue orange

IKI solution complex carbohydrate

dark red black

Biuret solution

protein blue violet, black

Sudan IV lipid dark red reddish- orange

What is a Control?

• An acknowledged measure of comparison for quantitative or qualitative value; a criterion.

Test for Simple CarbohydratesBenedict’s solution

• Benedict's solution is a chemical indicator for simple sugars such as glucose: C6H12O6.

• Aqua blue: negative test • yellow/green/brick red: positive test

Test for Simple CarbohydratesBenedict’s solution

• Unlike some other indicators, Benedict’s solution does not work at room temperature - it must be heated first.

Test for Complex Carbohydrates: Starches using IKI solution

• IKI solution (Iodine Potassium Iodine) AKA Lugol’s Iodine

• color change = blue to black

Test for Complex CarbohydratesIKI solution

• Iodine solution is an indicator for a molecule called starch.

• Starch is a huge molecule made up of hundreds of simple sugar molecules (such as glucose) connected to each other.

Test for Vitamin CIndophenol solution

• DPIP will turn colorless in the presence of Vitamin C.

Test for ChlorideSilver nitrate solution

• Silver nitrate reacts with chlorides to form a cloudy white precipitate.

Test for Protein (amino acids)Biuret solution

• Biuret solution dark violet blue to pinkish purple

QuestionWhy didn’t the test tube containing starch

change colors?

Who took Jerell’s iPod? • Jerell is an 11th grade student at NotHere High

School who works at McDonald’s on the weekends.

• While on break, Jerell was studying for his biology test and listening to his new iPod. There were four other workers taking a break at the same time, each having something different for lunch.

• Jerell‘s girlfriend stopped by near the end of his break and he rushed out to see her. Unfortunately, he forgot his iPod and biology book in the break room. When he realized, he hurried back and found only his biology book. Where his iPod was contained food crumbs instead. His iPod was gone!

• First Jerell freaked out, but he calmed down when he realized he could use his knowledge of macromolecules to figure out which of his coworkers left the crumbs on his textbook and who took his iPod.

ProcedureSimple carbohydrate

1. Add 5ml of food sample to test tube

2. Add 20 drops (3mL) of Benedict solution

3. Place test tube in a hot water bath for 5 minutes.

ProcedureFats (lipids)

1. Place one drop of food sample on a piece of brown paper.

2. Wait a few minutes for the spot to dry.

3. Hold the papers up to the light and determine if each spot is translucent.

ProcedureComplex carbohydrate

1. Add 1mL-2mL of food sample to test tube

2. Add 5 drops of IKI solution

ProcedureVitamin C

1. Add 1mL – 2mL of food sample to test tube

2. Add 5 drops of Indophenol solution

ProcedureChloride

1. Add 1mL – 2mL of food sample to test tube

2. Add 5 drops of silver nitrate solution

ProcedureProtein (amino acids)

1. Add 1mL – 2mL of food sample to test tube

2. Add 10 drops of Biuret solution

LAB SAFETY and CLEAN UP

WEAR safety goggles at all

times

THOROUGHLY CLEAN lab area and equipment

NO EDIBLE products

in lab