You Are What You Eat

Tuesday, Sept. 28, 2010

Objectives: SWBAT Describe 4 major biomolecules & describe why scientists use indicators.

Bellringer: What food categories are represented on this label?

Macromolecules

Macromolecules

Carbohydrates

Simple (sugars)

Complex (starches)

Lipids

(Fats & Oils)

Proteins

(Structural & Enzymes)

Nucleic Acids

(DNA & RNA)

CarbohydratesSimple Sugars &

Complex StarchesWhat foods contain carbohydrate?Foods high in carbohydrates include breads, pastas, beans, potatoes, bran, rice and cereals.

LipidsFats & Oils

What's the difference between saturated and unsaturated fat?The difference is down to their chemical composition. Fats are classified by their "saturation" - i.e. the amount of hydrogen atoms attached to the molecules of fat. Saturated fats are completely "saturated", i.e. each fat molecule is covered in hydrogen atoms. This type of fat is typically found in meat, meat products, dairy products, and coconut oil. A completely saturated fat would be very solid and have the consistency of hard wax.

Unsaturated fatsBoth polyunsaturated and monounsaturated fats are classified as unsaturated fats. Polyunsaturated fats, such as fish oils, are beneficial to health by lowering blood cholesterol levels, thus preventing the risk of heart disease. They also provide the body with linoleic acid, a fatty acid that helps us absorb fat-soluble vitamins and minerals. Some nutritional experts believe that monounsaturated fat, such as olive oil, have health benefits.

ProteinsStructural &

EnzymesWhat foods provide protein?Dietary sources of protein include meats, eggs, nuts, grain, legumes and dairy products such as milk and cheese. Protein from animal sources, such as meat and milk is called complete, because it contains all nine of the essential amino acids. Most vegetable protein is considered incomplete because it lacks one or more of the essential amino acids. You don't have to eat all the essential amino acids in every meal though - as long as you have a variety of protein sources throughout the day, your body will use what is needs from each meal.

Indicators

• Color indicators show the presence (+) or absence (-) of a substance

• Example:– Clear Blue Easy

Pregnancy Test

Color IndicatorsOrganic Molecules

• Paper Bag Lipids• Iodine Starches• Bennedict’s Sugars• Biuret’s Proteins

Homework

• Find a food label that is high in each of the 3 categories we talked about.– Carbohydrates– Lipids (Fat)– Protein

Principle types of Organic Molecules4 Principal Molecules Types of Principal Molecules Main components/ elements Foods/Special Facts Functions

Carbohydrates Polysaccharides

Starch

Glycogen

Cellulose

Monosaccharides

Glucose

Fructose

Lipids Fats

Oils

Waxes

Steroids

Proteins Amino acids

Enzymes

Nucleic Acids DNA

RNA

CARBOHYDRATES PROTEINS LIPIDS

Sugar Starch (Simple ) (Complex)

- + - + - + - +

Indicator used_sugar________________________starch_______________________

Indicator used________________________________________________________

Indicator used__________________________________________________________

Carbohydrate - SugarBenedicts Solution

BEFORE

AFTER

- +

CAUTION

Carbohydrate - StarchIodine Solution

BEFORE AFTER

- +

Lipids - FatsPaper Bag Test

Negative for lipids

Positive for lipids

ProteinBiuret Solution

BEFORE AFTER

- +

Iodine (Lugo’s) is a brown solution which turns black in the presence of starches.

Benedict's solution is used to detect the presence of simple sugars such as glucose. When a simple sugar is mixed in Benedict's solution and heated for a short period of time, it goes through a variety of color changes, eventually ending as an orange-red or brick red color.

Biuret’s reagent is a pale blue solution which turns purple in the presence of protein.

Benidicts BiuretsIodine

Paper Bag