How Organisms Obtain
Energy
Mr. Wagner
Vocabulary:
 Metabolism
 Photosynthesis
 Cellular Respiration
 Adenosine
Triphosphate (ATP)
 Anabolic
 Catabolic
All living organisms use energy to
carry out all biological processes.
Like the city that
never sleeps, cells
never sleep!
Transformation of energy
Your cells are
constantly working,
breaking down
molecules,
transporting
substances across
membranes,
growing, & dying.
This all requires
ENERGY the
ability to do work
Thermodynamics
 the study of
the flow &
transformation of
Energy in the
universe
Autotrophs & heterotrophs
All organisms need
energy.
Most energy comes
from the Sun.
Autotrophs make
their own food.
Heterotrophs need to
eat food to obtain
energy.
Metabolism
All of the
chemical
reactions that
occur within
a cell.
Metabolic pathway series of
chemical reactions in which the
product of 1 reaction is the substrate
for the next reaction
(a substrate binds to an enzyme to
help speed up chemical reactions)
2 types of metabolic
pathways:
1) Catabolic
release E by
breaking down
large molecules
into smaller ones
2) Anabolic use
the E released by
catabolic to take
small particles &
put them together
to make bigger
ones
Photosynthesis is
the anabolic
pathway that
takes light
energy from the
Sun & converts
it to chemical
energy for use
by the cell.
Autotrophs: light +
CO2+ H2O = glucose
& oxygen
The energy stored in
the glucose can now
be used by other
organisms when they
eat it as food.
Cellular respiration is
catabolic pathway in
which organic
molecules are broken
down to release E for
use by the cell.
Oxygen is used to
break down organic
molecules, resulting
in the production of
CO2 & H2O
Cyclical! One
pathway’s
products are
other pathway’s
reactants.
ATP: The Unit of Cellular Energy
Energy comes in diff.
forms:
light E, mechanical E,
thermal E, & chemical
E.
In organisms,
chemcial energy can
be stored & then
converted into
another form of
energy when needed.
Like when your
muscles contract!
Adenosine
triphosphate
(ATP) the
most important
biological
molecule that
provides
chemical E
ATP structure
Most abundant
energy-carrier
molecule in cells.
ATP is made of an
adenine base, a
ribose sugar, & 3
phosphate groups.
ATP Function
It releases energy when the
nd
rd
bond between the 2 & 3
phosphate group is broken
forming a molecule called
adenosine diphosphate (ADP) &
a free phosphate group.
Review Section 1
Answer the following question:
 What are the two metabolic pathways?
 Catabolic & Anabolic
Answer the following question:
 What is the first law of thermodynamics?
 Law of Conservation
Answer the following question:
 Chemical reactions in a cell are referred to as the cells
____________.
 Metabolism
Answer the following question:
 Where does all the energy for organisms come from?
 The Sun
Answer the following question:
 What does ATP stand for?
 Adenosine Triphosphate
Answer the following question:
 What are the three molecules that make up an ATP molecule?
 An adenine molecule
 A ribose sugar
 3 phosphates (phosphate group)
Answer the following question:
 What are two examples of a catabolic pathway?
 Cellular Respiration & Diet Pills
Answer the following question:
 What are heterotrophs?
 Organisms that rely on others to obtain energy
Answer the following question:
 What is a metabolic pathway?
 Where the reactants make a product, and the product is used
in another chemical reaction.
 A+BC
C+DE
E+FG
Answer the following question:
 Where is the bond broken to release energy in an ATP
molecule?
 Between the 2nd & 3rd phosphate group.
Answer the following question:
 What is the 2nd law of thermodynamics?
 Entropy Increases
Answer the following question:
 What are autotrophs?
 Organisms that make their own energy.
Answer the following question:
 What is entropy?
 Heat
Chapter 8 Section 1 Practice Problems
 YOU MUST WRITE OUT THE QUESTION &
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COMPLETELY ANSWER TO RECEIVE FULL CREDIT!
1. Recall the basic components of ATP.
2. Paraphrase the first law of thermodynamics.
3. Contrast catabolic pathways and anabolic pathways.
4. Examine how nearly all energy for life comes directly or
indirectly from the Sun, given that heterotrophs get their
energy from the food that they eat.
5. Classify the synthesis of a protein from amino acids as
anabolic or catabolic. Explain.