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Photosynthesis & Cellular
Respiration
Cellular Energy
Or
Bioenergetics

How does energy
from the sun
become energy for
life?

Organisms called
producers convert
light energy to
chemical energy using
a process called
photosynthesis.
PhotosynthesisAmoeba Sisters

The chemical
energy produced in
photosynthesis is in
the form of sugar.
 This allows
producers to store
the energy for later
use.
Photosynthesis
Method of converting sun energy into
chemical energy usable by cells
 Autotrophs utilize this process

–
Photoautotrophs- light
– Chemoautotrophs- chemicals

Equation
6CO2 + 6H2O + light → C6H12O6 + 6O2
Fill It In …
The goal of photosynthesis is …
Photosynthesis takes place
within the cell

In eukaryotic cells,
organelles called
chloroplasts are the
site of photosynthesis
Photosynthesis takes place
within the cell

Chloroplasts are filled with a pigment called
chlorophyll.
 This pigment allows the cell to “gather”
energy from light waves.
Photosynthesis takes place
within the cell

Some prokaryotic cells
can photosynthesize,
but they do NOT have
chloroplasts.
 They do, however,
contain chlorophyll.

Photosynthesis is a metabolic
pathway. This means it is a series of
chemical reactions. All of these
reactions can be simplified into one
chemical equation:
CO2 + H2O + sunlight (radiant energy) -> C6H12O6 + O2
(reactants)
(products)
http://www.youtube.c
om/watch?v=wj8TGh
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CO2 + H2O + sunlight (radiant energy) -> C6H12O6 + O2

The reactants (things that
are used) for
photosynthesis are
obtained from the
environment.
 The carbon dioxide enters
the leaves from the air
and the water enters the
roots from the soil.
CO2 + H2O + sunlight (radiant energy) -> C6H12O6 + O2

The products (things
that are made) of
photosynthesis include
sugar and oxygen.
 Sugar is stored in the
cell and used as food.
 Oxygen is released into
the air.
Electron Carriers

Carrier molecule- a compound that can
accept a pair of high-energy electrons
and transfer them along with most of
their energy to another molecule
–
Process: electron transport
– Molecule: electron transport chain
NADP+: NADP+ accepts and holds 2
high-energy electrons along with H+
 When this occurs it becomes NADPH
 NADPH can then carry high-energy
electrons to chemical reactions
elsewhere

Light-Dependent Reactions
Require light
 Produce oxygen gas
 Convert ADP and NADP into ATP and
NADPH

Light-Dependent Reactions
Pigments in photosystem II absorb
light
Energy is absorbed by electrons
which are passed on to electron
transport chain
1.
2.
-
Electrons come from breaking bonds
between water molecules
-
Create 2 electrons, H+ ions, and
oxygen
Light-Dependent Reactions
3. Electrons move through electron transport
chain
–
–
from photosystem II to photosystem I
Energy is used to transport H+ ions from
stroma to inner thylakoid
4. Pigments in photosystem I use energy from
light to reenergize the electrons
–
–
NADP+ picks up high energy electrons and H+
ions
Becomes NADPH
Light-Independent Reaction
Calvin Cycle
 Uses ATP and NADPH to produce
high-energy sugars
 Does not require light

Calvin Cycle
1.
6 CO2 molecules enter cycle
–
–
Combine with 6 5-carbon molecules
Result = 12 3-carbon molecules
2. 3-carbon molecules are converted into
higher-energy forms (energy from ATP
and NADPH)
3. 2 3-carbon molecules are removed from
cycle
–
Used to produce sugars, lipids, amino acids,
etc.. For metabolism and growth of plant
Calvin Cycle
4. Remaining 10 3-carbon molecules are
converted back to 6 5-carbon
molecules
–
Combine with 6 new carbon dioxide
molecules to begin the next cycle
Factors affecting Photosynthesis

Water
–
Lack of water can slow or even stop
photosynthesis
– Desert plants have waxy coating to reduce
water loss

Temperature
–

Enzymes function at particular temp ranges
Intensity of Light
–
Increasing light increases rate of
photosynthesis
– There is a maximum rate of photosynthesis
Fill It In …
Reactants for photosynthesis:
1.
2.
3.
Products of photosynthesis:
1.
2.

Photosynthesis
provides no DIRECT
source of energy for
the cell.
 The cell must convert
the sugar produced to
another form of
energy: ATP
What is ATP, and why should I
care?

ATP stands for
adenosine
triphosphate
 This basically
means that it is a
chemical with three
phosphate groups
attached.
What is ATP, and why should I
care?

The cell uses ATP for
energy.
 ATP is much smaller
and faster to use than
a larger molecule such
as sugar.
 The energy in ATP is
in the bonds
connecting the four
parts together.
Energy and ATP

ATP
–
Adenosine
triphosphate
– Adenine, 5-carbon
sugar, 3 phosphate
groups

ADP
–
Adenosine
diphosphate
– Adenine, 5-carbon
sugar, 2 phosphate
groups
Fill It In …
ATP is used for …
What is ATP, and why should I
care?



When the cell needs
energy from ATP, it uses
enzymes to break the
third phosphate off of the
molecule.
The energy released is
used for things in the cell
such as active transport
Removing the third
phosphate creates ADP
and a loose phosphate
ENERGY
What is ATP, and why should I
care?

ATP can be
recycled.
 When more energy
is available, a third
phosphate is added
to ADP to make
more ATP.
ADP and ATP

Storing energy
–

When a cell has energy available, it can store
small amounts by adding a phosphate group to
ADP, producing ATP
Releasing energy
Breaking bonds between the 2nd and 3rd
phosphate groups
– Powers several cellular activities
–
 Active
transport, protein synthesis, muscle
contraction
How do cells use the sugar to
Cellular Respirationmake ATP?

All cells must use a
process called
cellular respiration
to create ATP.
 Cellular respiration
converts sugar
(produced in
photosynthesis) to
create ATP
 Cellular respiration
takes place in the
Mitochondria
Amoeba Sister
Fill It In …
The goal of cellular respiration is …
Cellular respiration takes place
within the cell

In eukaryotic cells,
organelles called
mitochondria are
the sites of cellular
respiration
Cellular respiration takes place
within the cell

Mitochondria use
many enzymes to
break down sugar
(glucose) and store
the energy in the
chemical bonds of
ATP
Cellular respiration takes place
within the cell

Prokaryotes also
use cellular
respiration, but the
do NOT have
mitochondria.
 Instead,
prokaryotes use
parts of their cell
membrane.
Fill It In …
Types of organisms that use cellular
respiration:

Cellular respiration is also a metabolic
pathway. The simplified equation for
cellular respiration is:
C6H12O6 + O2 -> CO2 + H2O + ATP
(reactants)
(products)
C6H12O6 + O2 -> CO2 + H2O + ATP



The reactants of
respiration are glucose
and oxygen.
The sugar (glucose) is
obtained from the
vacuole (in plant cells)
or from ingestion
(eating) of food.
If oxygen is used, it is
obtained from the air.
C6H12O6 + O2 -> CO2 + H2O + ATP



The products of
respiration are ATP,
water, and carbon
dioxide.
The water and carbon
dioxide are released
into the environment as
waste products.
ATP is kept in the cell
for use as an energy
molecule.
Cellular Respiration

Breakdown of glucose to produce energy
–
–
1g of sugar releases 3811 calories of heat energy
Calorie- amount of energy needed to raise the temp of 1g
of water 1˚ Celsius
6O2 + C6H12O6 → 6CO2 + 6H2O + energy

Steps:
–
–
–
Glycolysis
Krebs Cycle
Electron Transport Chain
Glycolysis
Process in which one molecule of
glucose is broken in half, producing 2
molecules of pyruvic acid (3-carbon
compound)
 In cytoplasm
 2 ATP → 4 ATP
 NAD+ = electron carrier

–
Accepts 4 high-energy electrons
– Becomes NADH
Glycolysis
Energy yield is small but happens very
fast
 Does not require oxygen
 Problem: NAD+ molecules fill up with
electrons; without NAD+ ATP
production stops

Fill It In …
Reactants of cellular respiration:
1.
2.
Products of cellular respiration:
1.
2.
3.
There are two types of cellular
respiration: aerobic and
anaerobic
There are two types of cellular
respiration:

Aerobic
respiration
requires the use of
oxygen and makes
A LOT of ATP
Krebs Cycle
Pyruvic acid is broken down into
carbon dioxide in a series of energyextracting reactions
 Aerobic- requires oxygen
 AKA citric acid cycle – because citric
acid is the first compound produced
 In mitochondrion

Krebs
Cycle
Krebs Cycle

Pyruvate Oxidation:
–
Pyruvic acid enters mitochondrion
– A carbon atom is removed to form CO2
– The other 2 carbon atoms are joined to
coenzyme A to form acetyl-CoA
A. Acetyl-CoA adds to a 4-carbon
molecule producing a 6-carbon
molecule called citric acid
Krebs Cycle
B. -Citric acid is broken down to produce a 5-carbon chain
- CO2 is released
- electrons transferred to energy carriers
C.- 5-carbon chain is broken down into a 4 carbon chain
- CO2 is released
- ATP is produced
D. – 4 carbon chain is ready to accept acetyl CoA to start
cycle all over
- FAD is converted to FADH2
- NAD+ is converted to NADH
Electron Transport Chain
Uses high-energy electrons from the
Krebs cycle to convert ADP to ATP
 In mitochondrion

Electron Transport Chain
A.-NADH and FADH2 are passed along ETC
and transfer their electrons down ETC
 Eukaryotes:
membrane of mitochondrion
 Prokaryotes: cell membrane
–
H+ ions are transferred to intermembrane
space
B.-electrons from ETC combine with H+ ions
and oxygen to produce H2O
Electron Transport Chain
C. Energy is used to transport of
hydrogen ions by 2 high-energy
electrons
–
H+ ions build up in the intermembrane
space making it positively charged
– The other side of the membrane is
negatively charged
Electron Transport Chain
D.-Inner membranes of mitochondria
contain ATP synthase
- ATP spins when H+ ion crosses
membrane
- While rotating, the enzyme grabs a
low-energy ADP and attaches a
phosphate producing ATP
Totals
Glucose = 2 ATP
 Krebs + ETC = 34 ATP
 Total = 36 ATP


Final wastes: water and carbon dioxide
There are two types of cellular
respiration:


Anaerobic respiration
(also called
fermentation) takes
place when no oxygen
is available to the cell
and produces very little
ATP.
However, this process
is much faster than
aerobic respiration.
Fermentation

Releases energy from food molecules
by producing ATP in the absence of
oxygen
–

Anaerobic- not in air
2 main types
–
Alcoholic fermentation
– Lactic acid fermentation

Convert NADH to NAD+
–
Allows glycolysis to continue producing a
steady supply of ATP
Alcoholic Fermentation
Pyruvic acid + NADH → alcohol + CO2 + NAD+
 Causes bread dough to rise
 Yeast in dough runs out of oxygen, begins
fermentation which produces CO2

Lactic Acid Fermentation
Pyruvic acid + NADH → lactic acid + NAD+
 Produced in muscles during rapid exercise
when the body cannot supply enough
oxygen to the tissues
 Some unicellular organisms produce lactic
acid as a waste product

–
Cheese, yogurt, buttermilk, sour cream
– Pickles, sauerkraut
Fill It In …
Differences in ATP production in aerobic
vs. anaerobic respiration:
Aerobic Anaerobic -
Fill It In …
Anaerobic respiration is also called …
Types of anaerobic respiration:

In most microorganisms, fungi, and plant cells,
anaerobic respiration produces alcohol as a waste
product (alcoholic fermentation)
 Alcohol fermentation also produces carbon dioxide
gas
 Alcohol fermentation occurs in yeast
–
–
The carbon dioxide causes dough to rise
The alcohol burns off when the dough is baked
Types of anaerobic respiration:

In animal cells, anaerobic respiration
produces lactic acid as a waste product
(lactic acid fermentation)
 This mostly occurs in muscle cells.
 Build up of lactic acid causes cramps.
Uses for anaerobic respiration
A key idea …

Photosynthesis and
respiration form a
cycle!
A key idea …

Photosynthesis and
respiration form a
cycle!
A key idea …

The products from one reaction become the
reactants for the other reaction
A key idea …

The products from one reaction become the
reactants for the other reaction
A key idea …
Check Yourself!
1.
2.
3.
4.
5.
6.
7.
8.
9.
What pigment AND reactants are required for
photosynthesis to occur?
What does photosynthesis produce?
Where does photosynthesis occur in eukaryotic cells?
Where is the energy in ATP stored?
Why does the cell use ATP instead of sugar for
energy?
What reactants are required for cellular respiration to
occur?
What does cellular respiration produce?
Where does cellular respiration occur in eukaryotic
cells?
How is fermentation alike and different from aerobic
respiration?
Check Yourself!
1.
What pigment AND reactants are required for
photosynthesis to occur?
CHLOROPHYLL
CARBON DIOXIDE (CO2)
WATER (H2O)
SUNLIGHT (ENERGY)
Check Yourself!
2.
What does photosynthesis produce?
GLUCOSE (C6H12O6) OR SUGAR
OXYGEN (O2)
Check Yourself!
3. Where does photosynthesis occur in eukaryotic cells?
CHLOROPLAST
Check Yourself!
4. Where is the energy in ATP stored?
IN THE BONDS CONNECTING THE PHOSPHATES
Check Yourself!
5. Why does the cell use ATP instead of sugar for energy?
ATP IS FASTER AND SMALLER TO USE
Check Yourself!
6. What reactants are required for cellular respiration to
occur?
GLUCOSE (C6H12O6) OR SUGAR
OXYGEN (O2)
Check Yourself!
7. What does cellular respiration produce?
CARBON DIOXIDE (CO2)
WATER (H2O)
ATP (ENERGY)
Check Yourself!
8. Where does cellular respiration occur in eukaryotic
cells?
MITOCHONDRIA
Check Yourself!
9.
How is fermentation alike and different from aerobic
respiration?
ALIKE - USES GLUCOSE AS A REACTANT
PRODUCES ATP (ENERGY)
DIFFERENT - AEROBIC USES OXYGEN
FERMENTATION DOES NOT
AEROBIC PRODUCES LOTS OF ATP
FERMENTATION PRODUCES ONLY 2
ATP
Comparing Photosynthesis &
Respiration
Photosynthesis
Cellular
Respiration
Function
Energy Storage
Energy Release
Location
Chloroplasts
Mitochondria
Reactants
CO2 and H2O and C6H12O6 and O2
sun
C6H12O6 and O2
CO2 and H2O
and energy
Products
Equation
6CO2 + 6H2O +sun
 C6H12O6 + 6O2
C6H12O6 + 6O2
6CO2 + 6H2O +
energy
Cell Energy
Cell Energy
Processes
include:
Photosynthesis
Photosynthesis
is a
STERNGRR
process
Cellular
Respiration is
a STERNGRR
process
and
Cellular
Respiration
The two
processes
work
together
in a cycle!
Photosynthesis
Involves making FOOD (sugar/glucose) for nutrition
CO2 + H2O + sun  C6H12O6 + O2
REACTANTS
PRODUCTS
Occurs in the CHLOROPLASTS of plant cells.
Uses the green pigment CHLOROPHYLL to capture light energy
Green light is reflected… all other wavelengths of light are
absorbed by the plant.
Photosynthesis
What is going in and coming out of the plant?
ATP
The food made
in
photosynthesis
is used to
make energy
for cells!
Organisms
(including
plants) must
use this food to
produce
energy
Plants make
food for all
living
organisms
(sugar)
Food is NOT energy!
They are 2 different
things!
Adenosine
Energy is stored in a
chemical bond – when
the bond is broken,
energy is released!
P
Energy
P
P
ATP is the
energy
molecule
for cells
Cellular Respiration
Involves using food made in photosynthesis for
respiration, to make ATP for energy.
C6H12O6 + O2
REACTANTS
 CO2 + H2O + ATP
PRODUCTS
Occurs in the Mitochondria of ALL cells
Cellular Respiration
Cellular
respiration
can take
place
WITH
Aerobic
respiration
occurs when
oxygen is
present
Anaerobic
respiration
(fermentation)
takes place
when oxygen
is NOT present
Makes
a LOT
of ATP
Makes
a little
ATP
Or
WITHOUT
Oxygen!
In plants and
microorganisms:
Alcoholic
fermentation
In animals:
Lactic acid
fermentation