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 What is energy?
 How do we get energy?
 Do all organisms get energy the same way
as we do?
Objectives
 To define energy.
 To list the different types of energy.
 To explain the laws of thermodynamics.
 To understand the general idea of
photosynthesis and respiration.
Cellular Energy!!
Chapter 8
8.1: What is energy?!
 Energy The ability to do work
 Thermodynamics is the study of the flow and transformation of
energy in the universe.
*All cells need energy for many
Functions that they carry out
To stay alive
Types of Energy
 Chemical- energy found in bonds between
atoms of every molecule:
 Released when bonds break
 Glucose: Sugar that is major energy source,
used to make ATP (ENERGY!!)
•Solar Energy- Energy from Sunlight:
•Can’t be used directly:
•Plants convert solar energy to usable chemical
energy (Glucose)
Laws of Thermodynamics
 First law —energy can be converted from
one form to another, but it cannot be
created nor destroyed.
 Ex. Chemical Energy to Mechanical
Energy
Laws of Thermodynamics
 Second law —energy cannot be converted
without the loss of usable energy.
 Ex. Energy Lost as Heat
Second Law of Thermodynamics
 Entropy
 Measure of disorder (randomness)
 Measure of unusable energy
 Entropy always ___________.
Review of Reactions…
 Endothermic- uses energy to make bonds
 H+H
H2
Energy put in
 Exothermic- breaks bonds and releases
energy
 H2
H + H
Energy Released
Autotrophs and Heterotrophs
 Autotrophs are organisms that make their
own food.
-Ex.
 Heterotrophs are organisms that need to
ingest food to obtain energy.
Ex.
Metabolism
 Metabolism:
 All chemical reactions in a cell
 Two types of Metabolic Pathways:
 Catabolic: Release energy by breaking down
larger molecules
 Anabolic: Use energy to build larger
molecules from smaller ones
Think- Pair - Share
 Of the following examples, list which ones
are catabolic and anabolic
 1. Amino acids becoming polypeptide chain
 2. Glucose becoming glycogen
 3. Your body breaking down food
 4. Fatty Acids becoming triglycerides
Adenosine Tri Phosphate
(ATP)
 Structure:
 Adenine base, ribose sugar, and 3
phosphate groups
Adenosine Tri Phosphate
(ATP)
 Function:
 bond breaks between the second and third
phosphate groups to release energy
 Creating adenosine diphosphate (ADP) and a
free phosphate group.
Processes involving
Energy…
 Cellular respiration —organic
molecules are broken down to release
energy for use by the cell
-type of process:
 Photosynthesis —light energy from the
Sun is converted to chemical energy for
use by the cell
-Type of Process:
Glucose