Transcript - Your Science Teacher

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 Information
INDICATOR
MACROMOLECULE
NEGATIVE POSITIVE
TEST
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
reddishorange
What is a Control?
• An acknowledged measure of comparison for
quantitative or qualitative value; a criterion.
Test for Simple Carbohydrates
Benedict’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 Carbohydrates
Benedict’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 Carbohydrates
IKI 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 C
Indophenol solution
• DPIP will turn colorless in the presence of
Vitamin C.
Test for Chloride
Silver 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
Question
Why 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.
Procedure
Simple 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
bath for 5 minutes.
water
Procedure
Fats (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.
Procedure
Complex carbohydrate
1. Add 1mL-2mL of food sample to test
tube
2. Add 5 drops of IKI solution
Procedure
Vitamin C
1. Add 1mL – 2mL of food sample to
test tube
2. Add 5 drops of Indophenol solution
Procedure
Chloride
1. Add 1mL – 2mL of food sample to test
tube
2. Add 5 drops of silver nitrate solution
Procedure
Protein (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
NO EDIBLE
products
in lab
THOROUGHLY
CLEAN lab area
and equipment