Energy for Life
Chapter 4 Section 3
p. 113- 117
A. Cells use Chemical Reactions

Cells use chemical
reactions to change
the chemical energy
stored in food into
forms needed to
perform cell
activities
A. Cells use Chemical Reactions

1. Metabolism – The
total of all
chemical reactions
in an organism
A. Cells use Chemical Reactions

2. Chemical reactions
require enzymes
(which cause, or
speed up, or slow down
reactions without
themselves being
changed and
therefore can be used
again and again.)
B. Photosynthesis

The process that plants
and other organisms use
to convert sunlight
energy into chemical
energy or sugars
(glucose) to be used as
food.
B. Photosynthesis


1. Producers – organisms that make their own
food
Consumers – organisms that can not make
their own food.
B. Photosynthesis


Chlorophyll and
other pigments are
used in
photosynthesis to
capture sunlight
Which is used to
produce sugar
(glucose) and oxygen
C. Respiration

The process in which chemical reactions break
down food molecules into simpler substances
and release stored energy
C. Respiration

1. Respiration of carbohydrates begins in the
cytoplasm
C. Respiration


1. Respiration of carbohydrates begins in the
cytoplasm
a. Carbohydrates are broken down into glucose
molecules
C. Respiration



1. Respiration of carbohydrates begins in the
cytoplasm
a. Carbohydrates are broken down into glucose
molecules
b. Each glucose molecule is broken down into
two simpler molecules, releasing energy.
+
+
C. Respiration

2. Respiration moves into the mitochondria
C. Respiration


2. Respiration moves into the mitochondria
a. The two simpler molecules are broken down
again, releasing much more energy.
+
C. Respiration



2. Respiration moves into the mitochondria
a. The two simpler molecules are broken down
again, releasing much more energy.
b. This process uses oxygen and produces
carbon dioxide (CO2) and water as waste
products.
C6H12O6 + 6O2  6CO2 + 6H2O + energy
glucose
oxygen
carbon
dioxide
water
D. Fermentation

Cells that do not have enough oxygen for
respiration use this process to release some of
the energy stored in glucose molecules
D. Fermentation


Cells that do not have enough oxygen for
respiration use this process to release some of
the energy stored in glucose molecules
1. Entire process occurs in the cytoplasm.
D. Fermentation



Cells that do not have enough oxygen for
respiration use this process to release some of
the energy stored in glucose molecules
1. Entire process occurs in the cytoplasm.
2. Produces lactic acid, alcohol, and carbon
dioxide as wastes
E. Comparisons

Photosynthesis and respiration are almost the
opposite of each other.
E. Comparisons


Photosynthesis and respiration are almost the
opposite of each other.
1. Photosynthesis produces (end products are)
glucose and oxygen which are used in
respiration
6CO2 + 6H2O
carbon
dioxide
water
+ energy
sunlight
energy

C6H12O6
glucose
+ 6O2
oxygen
E. Comparisons



Photosynthesis and respiration are almost the
opposite of each other.
1. Photosynthesis produces (end products are)
glucose and oxygen which are used in respiration
2. Respiration produces (end products are) carbon
dioxide and water, which are used in
photosynthesis
6CO2 + 6H2O
carbon
+ energy
water
sunlight
dioxide
C6H12O6
glucose

C6H12O6
glucose
+ 6O2
oxygen
energy
+ 6O2
oxygen

6CO2 +
carbon
dioxide
6H2O + energy
water
chemical
energy