Energy Transfer (8.1)
State Standard
SB3A. Explain the cycling of energy through
the processes of photosynthesis and
respiration.
Chapter 8
Cellular Energy
8.1 How Organisms Obtain Energy
Transformation of Energy
 Energy is the ability to do work.
•All organisms depend on the flow of energy.
•The sun is the ultimate source of energy for
almost all food chains.
Exception: Hydrothermal Vents deep in
the ocean.
Chapter 8
Cellular Energy
8.1 How Organisms Obtain Energy
Autotrophs and Heterotrophs
 Autotrophs are organisms that make their
own food. (They are the entry point for
energy into the food chain.)
 Heterotrophs are organisms that need to
ingest food to obtain energy.
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
(carboyhydrates) for use by the cell
 Cellular respiration—organic molecules
(mainly carbs) are broken down to release
energy for use by the cell
Chapter 8
Cellular Energy
8.1 How Organisms Obtain Energy
Metabolism cont’d.
REMEMBER…
 Photosynthesis = Energy Storage
 Cellular respiration = Energy Release
Chapter 8
Cellular Energy
8.1 How Organisms Obtain Energy
ATP: The Unit of Cellular Energy
 Adenosine Triphosphate
- a special molecule that
stores & releases energy
in its bonds for the needs
of the cell.
Chapter 8
Cellular Energy
8.1 How Organisms Obtain Energy
ATP cont’d
 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.
Chapter 8
Cellular Energy
8.1 How Organisms Obtain Energy
ATP cont’d
 Phosphorylation = when
the last phosphate group
is transferred to another
molecule with the help of
an enzyme.
Chapter 8
Cellular Energy
8.1 How Organisms Obtain Energy
ATP cont’d
 Energy can be stored by
adding a phosphate
group back to the ADP
molecule.
Chapter 8
Cellular Energy
8.1 How Organisms Obtain Energy
ATP cont’d
Cells use ATP to…
 make new molecules
 build organelles &
membranes
 maintain homeostasis
 move
 transmit impulses
 produce light
 etc.
Chapter 8
Cellular Energy
8.1 Formative
Questions
All of the energy from the
food you eat comes from
the sun.
A. true
B. false
1.
2.
0%
B
A
0%
A
B
Chapter 8
Cellular Energy
8.1 Formative
Questions
Why is adenosine triphosphate (ATP) such an
important biological molecule?
1.
2.
3.
4.
A
B
C
D
0%
D
0%
C
0%
B
0%
A
A. It captures light energy
from the sun.
B. It is produced in anabolic
pathways.
C. It stores and releases
chemical energy.
D. It converts mechanical
energy to thermal energy.
Chapter 8
Cellular Energy
Chapter Assessment
Questions
Look at the following figure.
Which molecule is released
when ATP becomes ADP?
A. phosphate group
B. water molecule
C. ribose sugar
D. energy cells
1.
2.
3.
4.
0%
D
0%
C
0%
B
A
0%
A
B
C
D