Name: ______Date: ______Period: _____ Unit 6: ENERGY in LIVING SYSTEMS Introduction: Basics of Energy Production You’ll be having lunch later today…you might hear your stomach rumbling right now! Did you ever think about why you have to eat at all? You already know that most energy for living things come from the sun, but how do we receive that energy? Remember the cycle…

Sun Grass- Autotroph Deer-Heterotroph Bear-Heterotroph

Let’s say you are going to have a ham and cheese sandwich for lunch. Follow the path of energy back to the sun. Ham (Pig) Plants  Sun Cheese Milk  Cow Plants  Sun Bread Wheat  Sun

Sunlight is collected to create organic compounds. Organic means it contains carbon atoms in molecules.

These compounds store chemical energy and can be eaten by organisms or used by the one who created it. Metabolism is one of the characteristics of life and involves either using energy to build molecules or breaking down molecules in which energy is stored.

How to Build Molecules that Store Energy: The process in which light energy from the sun is collected and converted into chemical energy it is called photosynthesis. We give organisms that do this a special name: autotrophs. They make their own organic food from inorganic substances. Inorganic simply means not organic.

There are always exceptions in Biology, and we have said before that most living things get energy from the sun, but there are organisms that live in complete darkness all the time. Some prokaryotes (bacteria) that live at the bottom of the ocean get their energy from chemicals floating around them in the water that is why they are called chemotrophs.

1 How to Break Down Molecules that Store Energy: Organisms tend to mirror each other. So if one kind of organism creates organic molecules, another kind will break it down to get the energy. We call organisms that must get energy from organic compounds already made and not directly from sunlight or inorganic substances heterotrophs. Humans are an example of such an organism.

The process of cellular respiration is a form of metabolism like burning fuel that releases ATP for the cell to use. It can be thought of as the opposite of photosynthesis. So, we begin to see why animals are so dependent on plants!

Cellular Respiration Photosynthesis

Transfer of Energy using ATP: You are always hearing about burning calories, burning energy, or burning fuel. But cellular respiration is not like burning wood or paper. True burning, like in cellular respiration, releases energy very quickly, but in cells, it’s slower and more efficient because it needs to be used carefully so there is less waste.

Adensine Tri phosphate

The structure of ATP is important. Below, is a representation of what ATP looks like in simple form. Label the parts with the following: ribose, adenine, and phosphate groups.

Adensine

Ribose Triphosphate

H2O (water) + ATP  ADP + P + Energy ------reactants------products------

When looking at an equation like the one above, it is similar to an equation in math. You enter reactants or input on one side and then it equals products or the answer on the other side. So here we added water and ATP together and that resulted in ADP, a 2 phosphate group by itself, and the release of energy. There is a similar equation for photosynthesis and cellular respiration that you will learn.

So when you look at the structure of ATP, you will notice that there are ______(#) phosphate groups all clumped together on one end. They are held together loosely and when a water molecule comes along, it can bump one of the phosphate groups off and that releases energy. The ADP (or Adensine Di phosphate) is just what we call an ATP with only 2 (#) phosphate groups! The three phosphate are like a spring all crunched up and when the bond is broken, the spring is released.

Key terms:

Photosynthesis – Process by which plants and some other organisms use light energy to power chemical reactions that convert water and carbon dioxide into oxygen and high- energy carbohydrates such as sugars and starches.

Cellular Respiration – Process that releases energy by breaking down food molecules in the presence of oxygen, the Krebs cycle, and the electron transport chain.

Autotroph – Organism that can capture energy from sunlight or chemicals and use it to produce its own food from inorganic compounds, also called a producer.

Heterotroph – Organism that obtains energy from the foods it consumes; also called a consumer.

ATP (Adensine Tri-phosphate)– One of the principal chemical compounds that living things use to store energy. Questions:

1. Identify the primary source of energy that flows through most living systems.

2. The metabolism in autotrophs is called:

3. The metabolism in heterotrophs is called:

4. How are they different?

3 5. How is energy released from ATP?

6. Short Answer (in complete sentences) Compare/Contrast What is the relationship between photosynthesis and cellular respiration?

7. Are fungi heterotrophs or autotrophs?

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