Biology 5.1 Energy and Living Things

Photosynthesis and Cellular Respiration

Chapter ObjectivesToday, Students will. . .

Analyze flow of energy through living systems

Compare the metabolism of autotrophs with that of heterotrophs

Describe the role of ATP in metabolism

Describe how energy is released from ATP

Energy in Living Systems You get your energy from the

food you eat.

Where does the energy in your food come from?

Directly, or indirectly, almost all energy for living things comes from the sun.

1. Plants convert light energy to chemical energy through photosynthesis;

2. animals consume the plants,3. other animals consume the

smaller animals, 4. we consume the larger animals.

Flow of Energy through a System

Building Molecules that Store Energy

Metabolism involves either using energy to build molecules, or breaking down molecules in which energy is stored.

Photosynthesis is the process by which light energy is converted to chemical energy.

Autotrophs are organisms that use energy from sunlight to make organic compounds.

Autotrophs

Autotrophs, especially plants, are photosynthetic organisms.

Photosynthetic organisms 1. Take in carbon dioxide (CO2) and

water (H2O)2. Use the energy from sunlight as a

power source to create a reaction3. Convert the carbon dioxide +

water into food for the plant in the form of sugars

4. Give off oxygen as a product of this reaction

Heterotrophs

The chemical energy in inorganic compounds can be transferred to other organic compounds or to organisms that consume food.

Heterotrophs are organisms that must get energy from food instead of directly from sunlight.

We (humans) are Heterotrophs because we get our energy from food through the process of cellular respiration. Plants are autotrophs. All other

organisms in this food web areHeterotrophs.

Cellular Respiration

Cellular respiration is a process similar to burning fuel.

Cellular respiration is a metabolic process which releases the energy in food to make ATP.

This ATP provides cells with the energy they need to carry out cellular activities.

Transfer of Energy to ATP

The word burn is often used to describe how cells get energy.

The “burning of food” in a living cell is very different than burning wood in a fire.

When a log burns, energy is released quickly as heat and light.

Transfer of Energy to ATP

But in cells, chemical energy stored in food molecules is released gradually in a series of steps.

These steps are a series of “enzyme-assisted chemical reactions”.

Transfer of Energy to ATP

When cells break down food molecules, some of the energy in the molecules is released as heat.

Most of the remaining energy is stored temporarily in molecules of ATP.

Mitochondria MakingATP

Transfer of Energy to ATP

ATP is like a rechargeable battery that can take a charge, hold it, and deliver it’s energy to other locations in the cell when needed at a later time.

The energy released from ATP can be used to start other chemical reactions, such as those that build molecules.

Mitochondria MakingATP

What is ATP? Recall that ATP is a

nucleotide with two extra energy absorbing phosphate groups.

The three phosphate groups in ATP form a chain that branches from a 5 carbon sugar called ribose.

What is ATP?

This phosphate tail is unstable because the phosphate groups are negatively charged and repel each other.

The phosphate groups store energy like a compressed spring does.

This energy is released when the bonds that hold the phosphate groups together are broken.

ATP

Breaking this outer phosphate bond requires an input of activation energy.

The energy produced by the cell however is much greater than the activation energy used.

The result is a release of energy that the cell uses to power it’s metabolism (chemical reactions).

Reflect and Review Did we. . . .

Identify the primary source of energy that flows through most living things?

Understand the difference between an autotroph and a heterotroph when it comes to where they get their energy from?

Describe the role of ATP in metabolism?

Computer Lab Assignment Go on the internet and

produce a short one page flow chart in PowerPoint that

Demonstrates the flow of energy in a food chain from the sun to the autotrophs to heterotrophs to yourself as food

3 examples of food chains