Carbohydrates

The structure of a Carbohydrate is C(H2O). It is a carbon (Carbo) and a water molecule (Hydrate)

Class discussion:

What does it mean when someone goes on a diet and says they are avoiding or cutting back carbs? What do you think of when you hear the word Carbs?

Carbohydrates are sugars!

-A complex carbohydrate is a lot of sugars strung together like starch

Carbs are so important because they are how most organisms get their energy. In later sections of biology you will learn that the mitochondria which is the part of the cell responsible for providing energy to cells, makes all of its energy from carbohydrates. Without carbohydrates we would not be able to live.

    Sugars have their own name...they are called Saccharides

    -A monosaccharide is a single sugar molecule or a monomer of carbohydrate

    -A Disaccharide is 2 sugars stuck together. This is a polymer of carbohydrate

    -And a Polysaccharide is more than two sugars stuck together in a chain. These are also polymers

 Student Activity:

  I am going to hand each of you a cracker. Hold that cracker until all of us have one. When I say go you are going to start chewing that cracker. DO NOT SWALLOW! chew up the cracker and hold it in your mouth.

Starch is a complex carbohydrate which means it is a long change of sugars. We do not usually think of starchy foods as sugary. That is because our body needs to break a part those long polymer changes and turn it into simple sugars in order for it to taste sweet.

You swallow a cracker long before it gets broken into simple sugars. Now that you still have your chewed up cracker in your mouth, your saliva is performing hydrolysis on the carbohydrate polymers. You also have enzymes in your mouth that are speeding up that process.

What I want you to do now is raise your hand if your chewed up cracker is starting to taste sweet. If not that is okay, we can wait for it. This is the quietest this class will ever be. Those of you who are starting to taste sweet, that is because the cracker polymers have begun to break apart into simple sugars.

Okay, you can swallow now.

Some examples

    -Monosaccharides: Glucose, Fructose, Galactose, Ribose, Deoxyribose

    -Disaccharides: Sucrose (Glucose+Fructose) Lactose (Glucose+Galactose) Maltose (Glucose+Glucose)

    -Polysaccharides: Starch, Glycogen, Cellulose, Chitin

Class Discussion:

Lets talk about how the body uses each of these types of carbohydrates.

Lipids 

Lipids are oils, fats, waxes, and steroid hormones

     -lipids do not have a monomer. They are almost completely made up of hydrogen and carbon

     -A fat is formed by attaching three fatty acid subunits to a glycerol

    -This is why they are called a triglyceride

Fats are saturated and oils are unsaturated.

    -Saturated means it has all the hydrogens it can fit which causes the fat molecules to fit tightly together. This is why fats are solid at room temperature.

    -Unsaturated means that the lipid is missing some hydrogens which causes the fatty acid chains to bend. Because of the bending the molecules cannot fit tightly together. This is why unsaturated fatty acids are oils at room temperature.

Some foods are easier to use if they are a solid. Because of that we have found a way to make an unsaturated oil, solid at room temperature. We do it by adding hydrogens. Foods that have had hydrogen added to them are called hydrogenated. 

Student Activity:

Take out your device and find as many foods as you can that are hydrogenated. 

Question:

Is butter a saturated or unsaturated fat? 

Humans have used butter for cooking for hundreds of years, but butter is high in calories. So scientists hydrogenated vegetable oil making it a solid at room temperature. We call this margarine. When margarine first came out, it was advertised as the healthy alternative to butter.

Student Activity:

In small groups and using your computer, research the difference between butter and margarine. Which one is worse for you to eat. Why? 

In most situations, fats come from animals. If it comes from a plant it tends to be an oil. Peanuts come from a plant. So real peanut butter is an oil. Peanut butter is liquid at room temperature. But it is not enjoyable to spread a liquid on bread or food so we hydrogenate it to make it a solid.

Plants mostly use carbohydrates for everything. The reason is, photosynthesis makes carbohydrates. Plants store their extra energy as starch which is a complex carbohydrate. Animals on the other hand store their extra energy as fat.

Lipids contain much more energy that carbohydrates. But to use the energy stored in lipids the bonds need to be broken down. 

Sugar is a quick and easy energy source. Lipids is a great way to store energy long term.

    -Lipids are hydrophobic meaning they do not dissolve in water.

        -Because lipids are hydrophobic many organisms use them as water proofing

 -A phospholipid is a lipid that has both a hydrophobic side and a hydrophilic side

        -We use phospholipids to make soap

            -The hydrophobic side sticks to the oils on our skin and the hydrophilic side sticks to the water washing off the oil.

        -Our cells have a membrane that is made of two layers of phospholids. It is called a phospholipid bilayer

            -A phospholipid bilayer has many properties that assist with cell homeostasis but we will talk about that later when we talk about cells.

-Another important lipid is hormones.

        -Hormones are chemical messengers the body uses to talk to other cells

            -Steroids are a type of hormone

            -Since organisms are made up of mostly water, it is important to have a chemical messenger that does not dissolve in water. This is why our bodies us lipids to send messages.