CHAPTER 8 Cellular Energy

8-1 How Organisms Obtain Energy

JOURNALWhat are some of the different forms of energy?

What do organisms need energy for?

Launch Lab: How is Energy Transformed? Page 216 The flow of energy in living systems is

driven by a variety of chemical reactions and chemical processes. Energy is transformed from the Sun’s radiant energy to chemical energy to other forms of energy along the way. In this lab, you will observe two processes in which energy is transformed.

Transformation of Energy

Energy is the ability to do work.

Cellular Energy

Thermodynamics is the study of the flow and transformation of energy in the universe.

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.Example: Stored energy in food is converted to chemical energy when you eat, and then mechanical energy when you kick a ball.

Laws of Thermodynamics

Second law “Entropy increases” energy cannot be converted without the loss of usable energy. Energy that is “lost” is usually

converted to thermal energy Example – energy lost in food chains

Entropy is the measure of disorder, or unusuable energy, in a system

Autotrophs and Heterotrophs Autotrophs are organisms that make their own

food. Heterotrophs are organisms that need to

ingest food to obtain energy.

MetabolismAll of the chemical reactions in a cell

Catabolic Pathways – Release energy by breaking down large molecules into smaller molecules

Anabolic Pathways - Use the energy released by catabolic pathways to build larger molecules from smaller molecules

Result in the continual flow of energy in an organism

ANABOLIC PATHWAYPhotosynthesis

light energy from the Sun is converted to chemical energy for use by the cell

CATABOLIC PATHWAYCellular respiration

organic molecules are broken down to release energy for use by the cell

Metabolic PathwaySeries of chemical reactions in which the product of one reaction is the substrate for the next reaction

Photosynthesis(autotrophs)

Cellular Respiration(heterotrophs &

autotrophs)

Adenosine TriphosphateThe cell’s key to being able to store and

release energy

ATP: The Unit of Cellular Energy

ATP: The Unit of Cellular Energy

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.

ATP

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.

Quick CheckWhat is energy?The ability to do workCan energy be created? NoCan energy be destroyed?No

List some forms of energy.Thermal/heat, mechanical, chemical, lightAnalyze why living things need energy.To grow, to move, to reproduce, to break down food, etc…How do humans obtain energy?By eating and digesting food

Journal

Explain how ADP and ATP are like a battery in the cell. Which one is partially charged and which one is fully charged?

JOURNAL

Using vocabulary from 8-1, discuss the metabolic pathway that includes photosynthesis and cellular respiration.

JOURNAL

Explain how the ultimate source of energy for heterotrophs is the sun even though they cannot make their own food.

energy

thermodynamics

metabolism

Photosynthesis

cellular respiration

adenosine triphosphate (ATP)

Cellular Energy

Vocabulary

Section 1