1. Cellular Energy
Section 1: How Organisms Obtain Energy

2. Big Idea
Photosynthesis converts the Sun’s energy into chemical energy, while cellular respiration uses chemical energy to carry out life function.

3. All living organisms use energy to carry out all biological processes
Chapter 8
Cellular Energy
8.1 How Organisms Obtain Energy
All living organisms use energy to carry out all biological processes
Macromolecules are assembled and broken down, substances are transported across cell membranes, and genetic instructions are transmitted.
All of these cellular activities require energy.

4. Transformation of Energy
Chapter 8
Cellular Energy
8.1 How Organisms Obtain Energy
Transformation of Energy
Energy is the ability to do work.
Thermodynamics is the study of the flow and transformation of energy in the universe.

5. Laws of Thermodynamics
Chapter 8
Cellular Energy
8.1 How Organisms Obtain Energy
Laws of Thermodynamics
First law— (Law of conservation of energy)
energy can be converted from one form to another, but it cannot be created nor destroyed.
Examples:
Food is converted to chemical energy when you eat
Mechanical energy when you run or kick a ball

6. Laws of Thermodynamics
Chapter 8
Cellular Energy
8.1 How Organisms Obtain Energy
Laws of Thermodynamics
Second law—energy cannot be converted without the loss of usable energy.
“loss” energy is generally converted to thermal energy
Increases Entropy

7. Laws of Thermodynamics
Chapter 8
Cellular Energy
8.1 How Organisms Obtain Energy
Laws of Thermodynamics
Entropy –
The measure of disorder (or unusable energy) in a system

8. Autotrophs and Heterotrophs
Chapter 8
Cellular Energy
8.1 How Organisms Obtain Energy
Autotrophs and Heterotrophs
Nearly all the energy for life comes from the Sun

9. Autotrophs and Heterotrophs
Chapter 8
Cellular Energy
8.1 How Organisms Obtain Energy
Autotrophs and Heterotrophs
Autotrophs are organisms that make their own food.

10. Autotrophs and Heterotrophs
Chapter 8
Cellular Energy
8.1 How Organisms Obtain Energy
Autotrophs and Heterotrophs
Autotrophs are organisms that make their own food.
Examples:
Chemoautotrophs use inorganic substances such as hydrogen sulfide as a source of energy
Photoautotrophs (like plants) convert light energy from the Sun into chemical energy.

11. Autotrophs and Heterotrophs
Chapter 8
Cellular Energy
8.1 How Organisms Obtain Energy
Autotrophs and Heterotrophs
Heterotrophs are organisms that need to ingest food to obtain energy.
Examples:
Aphid
Lady bug

12. All of the chemical reactions in a cell
Chapter 8
Cellular Energy
8.1 How Organisms Obtain Energy
Metabolism
All of the chemical reactions in a cell
Photosynthesis—light energy from the Sun is converted to chemical energy for use by the cell
Cellular respiration—organic molecules are broken down to release energy for use by the cell

13. Metabolism Metabolic Pathway –
Chapter 8
Cellular Energy
8.1 How Organisms Obtain Energy
Metabolism
Metabolic Pathway –
Series of chemical reactions in which the product of one reaction is the substrate for the next reaction
Examples:
Catabolic pathways
Anabolic pathways

14. Metabolism Metabolic Pathway – Examples: Catabolic pathways
Chapter 8
Cellular Energy
8.1 How Organisms Obtain Energy
Metabolism
Metabolic Pathway –
Examples:
Catabolic pathways
Release energy by breaking down larger molecules into smaller molecules

15. Metabolism Metabolic Pathway – Examples: Anabolic pathways
Chapter 8
Cellular Energy
8.1 How Organisms Obtain Energy
Metabolism
Metabolic Pathway –
Examples:
Anabolic pathways
Use the energy released by catabolic pathways to build larger molecules from smaller molecules

16. Chapter 8
Cellular Energy
8.1 How Organisms Obtain Energy
Photosynthesis
Photosynthesis is the anabolic pathway in which light energy from the Sun is converted to chemical energy for use by the cell.
Autotrophs use light energy, carbon dioxide, and water to form glucose and oxygen

17. Chapter 8
Cellular Energy
8.1 How Organisms Obtain Energy
Cellular Respiration
Cellular Respiration is the catabolic pathway in which organic molecules are broken down to release energy for use by the cell.
Oxygen is used to break down organic molecules, resulting in the production of carbon dioxide and water

18. ATP: The Unit of Cellular Energy
Chapter 8
Cellular Energy
8.1 How Organisms Obtain Energy
ATP: The Unit of Cellular Energy
ATP (Adenosine Triphosphate) releases energy when the bond between the second and third phosphate groups is broken, forming a molecule called adenosine diphosphate (ADP) and a free phosphate group.

19. ATP: The Unit of Cellular Energy
Chapter 8
Cellular Energy
8.1 How Organisms Obtain Energy
ATP: The Unit of Cellular Energy
ATP structure
A nucleotide made of an adenine base, a ribose sugar, and three phosphate group

20. ATP: The Unit of Cellular Energy
Chapter 8
Cellular Energy
8.1 How Organisms Obtain Energy
ATP: The Unit of Cellular Energy
ATP function
ATP releases energy when the bond between the second and third phosphate groups is broken, forming a molecule called adenosine diphosphate (ADP) and a free phosphate group

21. Why is ATP useful to cells?
ATP can easily release and store energy by breaking and re-forming the bonds between its phosphate groups. This characteristic of ATP makes it exceptionally useful as a basic energy source for all cells.

22. Chapter
Cellular Energy
Section 1 Formative Questions
Which law of thermodynamics explains why the ladybug receives the least amount of usable energy? A B
First law—energy can be converted from one form to another, but it cannot be created nor destroyed.
Second law—energy cannot be converted without the loss of usable energy.
the first law of thermodynamics
the second law of thermodynamics
FQ 1

23. All of the energy from the food you eat comes from the sun.
Chapter
Cellular Energy
Section 1 Formative Questions
All of the energy from the food you eat comes from the sun.
true
false A B
FQ 2

24. Why is cellular respiration a catabolic pathway?
Chapter
Cellular Energy
Section 1 Formative Questions
Why is cellular respiration a catabolic pathway?
Energy is used to form glucose and oxygen.
Energy is converted from water to carbon dioxide.
Energy that is lost is converted to thermal energy.
Energy is released by the breakdown of molecules. A B C D
catabolism definition. Biochemical reactions that break down molecules in metabolism.
FQ 3

25. Why is adenosine triphosphate (ATP) such an
Chapter
Cellular Energy
Section 1 Formative Questions
Why is adenosine triphosphate (ATP) such an
important biological molecule?
It captures light energy from the sun.
It is produced in anabolic pathways.
It stores and releases chemical energy.
It converts mechanical energy to thermal energy. A B C D
FQ 4