Cellular Energy
Salem Science
Biology
Cellular Energy
Energy Release
Energy Production
Oxygen
available
Photosynthesis
(use of light)
Chemosynthesis
(uses oxidation of
inorganic molecules)
Cellular Respiration
No Oxygen
available
Fermentation
2 Types:
3 Stages:
Light
Dependent
Reactions
Light
Independent
Reactions
(Calvin
Cycle)
1. Glycolysis
2. Krebs Cycle
3. ETC
1. Lactic Acid
(human
muscles
2. Alcoholic
(yeast and
bacteria)
Introduction
 All
organisms must be able to obtain and
convert energy to carry out life functions,
such as growth and reproduction.
 Photosynthesis and chemosynthesis are
ways that organisms can trap fuel from the
environment and convert it into a
biologically useful energy source.
 Cellular respiration is a way that organisms
can break down energy sources to carry out
life’s processes.
Introduction (cont’d)
 Photosynthesis
takes place in plants,
algae, and some bacteria.
 Cellular respiration takes place in all
eukaryotic cells and some prokaryotic
cells.
 Chemosynthesis takes place only in
prokaryotic cells example bacteria.
ATP

ATP (adenosine triphosphate) is a molecule
that serves as the chemical energy supply for all
cells
 Adenine, the sugar ribose, and three phosphates
compose ATP.
 Since the phosphates all carry a negative charge,
they repel one another.
 The release of a great deal of energy occurs
when the last phosphate in ATP breaks off,
forming ADP (adenosine diphosphate) and P
(an inorganic phosphate molecule).
Structure of ATP
ATP (cont’d)


1.
2.
3.
4.
5.
6.
After the ATP molecule breaks down, cells
use the released energy to drive cellular
processes and reactions.
Examples of cellular processes that require
energy include:
heat production
muscle contractions
photosynthesis
cellular respiration
locomotion
and DNA replication
Checkpoint!
 Q:
What molecule serves as chemical
energy for the cell?
 A: ATP
 Q: What are the 3 components of ATP?
 A: Adenine, ribose sugar, and 3 phosphates
 Q: How is energy released from a molecule
of ATP?
 A: The 3rd phosphate breaks off
Photosynthesis
 Photosynthesis,
which takes place in the
chloroplast of a plant cell, is the process of
converting carbon dioxide, water, and light
energy into oxygen and high energy sugar
molecules.
 Here is the formula for this process:
6CO2 + 6H20 + light (energy)→ C6H12O6 (glucose) + 6O2
REACTANTS
PRODUCTS
Photosynthesis (cont’d)


1.
2.
Plants, algae, and some bacteria can use
the sugar molecules produced during
photosynthesis to make complex
carbohydrates such as starch or cellulose
for food.
The process of photosynthesis consists of
two basic stages:
Light-dependent reactions
Light-independent reactions (a.k.a. Calvin
Cycle)
Label the following: chloroplast,
granum, thylakoid
Photosynthesis (cont’d)
1.

2.
Light-dependent reactions are converts solar
energy into chemical energy.
The light dependent reaction begins with light
and water and produces oxygen gas. ADP and
NADP+ are converted into The energy carriers
(1) ATP and (2) NADPH.
Light-Independent reactions are chemical
reactions that convert carbon dioxide and
other compounds into glucose.
Photosynthesis (cont’d)
 After
a series of many chemical reactions,
glucose is the end result!
 The glucose can then be used as food to
enter cellular respiration, or it can be
converted to other carbohydrate products
such as sucrose or starch.
Checkpoint!
 Q:
What are the reactants of
photosynthesis?
 A: Carbon dioxide, water, and sunlight
 Q: What are the products of
photosynthesis?
 A: glucose and oxygen
 Q: What are the two stages of
photosynthesis?
 A: (1) light-dependent reactions and (2)
light-independent reactions.
Cellular Respiration
 Cellular
respiration is the process of breaking
down food molecules to release energy.
 Here is the formula for cellular respiration:
C6H12O6 (glucose) + 6O2→ 6CO2 + 6H20 + ATP (energy)
REACTANTS
 Notice
PRODUCTS
that the molecules present are the same
as photosynthesis.
 The difference is the products and reactants
have switched.
Cellular Respiration



1.
2.
3.
Animals, and some bacteria use cellular
respiration to break down food molecules.
The energy released through cellular
respiration is used to create ATP.
Cellular respiration occurs in three phases:
Glycolysis
Krebs cycle.
Electron transport chain
Diagram of Cellular Respiration:
Where does glycolysis take place?
Krebs and ETC?
Cellular Respiration (step 1)
1.



Glycolysis occurs in the cytoplasm. It will
break down glucose (a six carbon compound)
into two molecules of pyruvic acid (a three
carbon compound)
If glycolysis occurs without the presence of
oxygen, it is called anaerobic resp.
(fermentation)
Fermentation releases energy from food
molecules in the absence of Oxygen.
Provides a net gain of 2 ATP.
Cellular Respiration (step 2)
2.




Krebs Cycle is the second step of cellular
respiration.
The Krebs cycle is also known as the (1) citric
acid cycle and (2) tricarboxylic acid (TCA)
cycle.
The Krebs cycle begins when the pyruvic acid
formed in glycolysis moves into the
mitochondrion.
Pyruvic acid and oxygen are used to make citric
acid. (Aerobic Respiration)
Krebs cycle generates a net gain of 2 ATP.
Cellular Respiration (step 3)
 Electron
Transport Chain (ETC) is a series
of chemical reactions that take place in
proteins embedded in a membrane
(mitochondria) along which energized
electrons are transported
 As electrons are passed from molecule to
molecule, energy is released.
 ETC generates a net gain of 34 ATP.
checkpoint






Q: What is the purpose of cellular respiration?
A: break down glucose and release energy
Q: What are the 3 stages of cellular respiration?
How many net ATP’s does each stage produce?
A: Glycolysis-2 ATP, Krebs Cycle-2 ATP, and
Electron Transport Chain-34 ATP.
Q: Where (in the cell) do these stages take
place?
A: Glycolyis- in the cytoplasm; Krebs and ETCinside mitochondria
Chemosynthesis

Chemosynthesis is the process by which
inorganic chemicals are broken down to release
energy.
 The only known organisms that are able to carry
out chemosynthesis are bacteria.
 These organisms form the base of the food
chain around thermal vents found on the ocean
floor.
 These organisms are also found around other
aquatic volcanic vents like those around
Yellowstone National park.
Photosynthesis vs.
Cellular Respiration
Photosynthesis and
Cellular Respiration
CARBON DIOXIDE
SUNLIGHT
WATER
Glycolysis
“split sugar” into
Two 3-C molecules
Outside mitochondria
Chloroplast
Light
Reactions
Calvin
Cycle
GLUCOSE
Sunlight, carbon
dioxide, and water
are used to
produce a 6carbon sugar
(glucose)
PHOTOSYNTHESIS
6 carbon
molecule
Pyruvic
acid
Pyruvic
acid
Mitochondria
Krebs & ETC
6-Carbon sugar broken
down (with use of
oxygen) to release about
38 ATP molecules
CELLULAR RESPIRATION
 The
End
Structure of ATP
Label the following: chloroplast,
granum, thylakoid
Diagram of Cellular Respiration:
Where does glycolysis take place?
Krebs and ETC?
Photosynthesis and
Cellular Respiration
CARBON DIOXIDE
SUNLIGHT
WATER
Glycolysis
“split sugar” into
Two 3-C molecules
Outside mitochondria
Chloroplast
Light
Reactions
Calvin
Cycle
GLUCOSE
Sunlight, carbon
dioxide, and water
are used to
produce a 6carbon sugar
(glucose)
PHOTOSYNTHESIS
6 carbon
molecule
Pyruvic
acid
Pyruvic
acid
Mitochondria
Krebs & ETC
6-Carbon sugar broken
down (with use of
oxygen) to release about
38 ATP molecules
CELLULAR RESPIRATION