Download Photosynthesis and Cellular Respiration

Photosynthesis and
Cellular Respiration
Light Energy Harvested by Plants &
Other Photosynthetic Autotrophs
6 CO2 + 6 H2O + light energy → C6H12O6
+ 6 O2
THE BASICS OF PHOTOSYNTHESIS
• Almost all plants are photosynthetic autotrophs, as
are some bacteria and protists
– Autotrophs generate their own organic matter through
photosynthesis
– Sunlight energy is transformed to energy stored in the
form of chemical bonds
(c) Euglena
(b) Kelp
(a) Mosses, ferns, and
flowering plants
(d) Cyanobacteria
THE SUN: WHY IS IT
IMPORTANT?
Source of light energy
Source of heat energy
Gravitational attraction
Source of radiation
Day and night
Source of all energy(electricity)
Source of food for all organisms!!!!
SUN’S SPECTRUM
Pigment and Light
Energy from the Sun travels to the Earth as light.
We see sunlight as “white light” which is really different
wavelengths(ROYGBIV).
Plant gather the Sun’s energy with light-absorbing
molecules called PIGMENTS.
Pigments: photosynthetic organisms capture energy
using pigments.
Chlorophyll: pigments plants use to absorb light energy.
Plant have different pigments.
WHY ARE PLANTS GREEN?
Plant Cells
have Green
Chloroplasts
The thylakoid
membrane of the
chloroplast is
impregnated with
photosynthetic
pigments (i.e.,
chlorophylls,
carotenoids).
THE COLOR OF LIGHT SEEN IS THE
COLOR NOT ABSORBED


Chloroplasts
absorb light energy
and convert it to
chemical energy.
They absorb the
reds and blue.
Reflects the green.
That is why they
look green.
Light
Reflected
light
Transmitted
light
Chloroplast
Absorbed
light
Different pigments absorb light
differently
Different Pigments
– Chlorophyll a – green pigments in plants and
bacteria
– Chlorophyll b in green algae
– Carotenoids – orange, red, yellow when
chloroplast die in plants. Chlorophyll breaks
down first in the fall so we see these colors.
– Xanthophyll – yellow pigments in
diatoms(protists)
Figure 7.7
Why are Chloroplast Important?
The chloroplasts absorb the Sun’s energy and
use this energy to excite electrons which powers
photosynthesis. To break apart water and carbon
Dioxide, you must have energy!!!!
ATP for energy
ATP powers cellular work- made in photosynthesis
amd cellular respiration
 A cell does three main kinds of work:
 Mechanical work, beating of cilia, contraction of
muscle cells, and movement of
chromosomes(produces heat)
 Transport work, pumping substances across
membranes against the direction of spontaneous
movement
 Chemical work, driving endergonic reactions such
as the synthesis of polymers from monomers
High Energy Electrons and Molecules
Once the sun’s energy has been trapped and
excited an electron, what happens to it?
Electron Carrier: a molecule that picks up the
electron and uses this energy to break
apart bonds.
Examples of electron carriers: NADP and ATP
NADP captures two electrons of H and
becomes NADPH.
ADP becomes ATP!!!
How Does ATP Work?






So what?
Energy is stored in these bonds.
So?
The breaking of the chemical bond releases the
energy
ATP + H2O→ ADP + P + ENERGY
ATP is made in photosynthesis and
respiration!!!
ATP (adenosine triphosphate) is a a molecule that
carries energy that cells can use.
How Does ATP Work?


The bonds between phosphate groups can be
broken by hydrolysis which produces
energy!!!
ATP has 3 phosphate groups The bond to the
third bond is easily broken. When the third
bond is broken, energy is released. Becomes
ADP – no energy!!
Photosynthesis
Photosynthesis uses the energy of the sunlight to
convert water and carbon dioxide(reactants)
into high-energy sugars and oxygen(products)
Photosynthesis occurs in the parts of the chlorplasts.
There are three parts involved.
Parts of the Chloroplasts
Thylakoids: flat compartments in the chloroplast that
contain chlorophyll. LIGHT DEPEDENT REACTION
occurs here.
Grana: are stacks of thylakoids.
Stroma: fluid that is all around the grana inside
the chorplast. LIGHT INDEPENDENT REACTION
occurs here.

Occurs in the membrane of the thylakoids
Overview of Photosynthesis
Step 1 – Light dependent reaction(depends on Light)
Traps the sunlight and energy is moved along
the thylakoid membrane.
Water is broken in to O and H by the electrons tha
are in ATP and NADPH required for dark
reaction.
Oxygen given off as waste.
Photosystem I and photosystem II - pigments
Step 2 – Dark reaction(Calvin Cycle)
Carbon Dioxide now is added to cycle to build
glucose.Uses ATP and electrons from light
reaction to make glucose.
Electron transport chains and
photosystems

Photosystems: cluster of chlorophyll and
proteins absorb the sun’s energy and generate the
high
energy electrons that are passed to the
electron carrier molecules.

Their energy ends up in ATP and NADPH
Photosynthesis
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Step 1 – Light Dependent Reaction
The light reactions convert solar energy to
chemical energy. Takes place in thylakoids.
Photosystem II and electron transport
1. chlorophyll absorbs the sun’s energy.
2. Energy as electrons is moved along the
membrane(electron transport chain)
3. Water is split into H and O. O released as waste
through stoma.
4. H is pumped over and over again in the
membrane until they build up.
Plants produce O2 gas by splitting H2O

The O2 liberated by photosynthesis is made from
the oxygen in water (H+ and e-)
Electron Transport Chain
When the electrons are excited from the light reaction,
they are passed along the membrane through the
protein pumps. They passed from Photosystem I to
photosystem II.
Photosynthesis
Photosystem I
1.1. Electrons from photosytem II is moved
along the membrane to photosystem I.
2.2. Chlorophyll continue to adsorb sunlight
and free electrons.
3.3. Electrons are added to NADPH which is
the energy carrier for the rest of
photosynthesis.
4.4. The electrons are pumped though a
channel as part of an enzyme ATP
synthase to make ATP.
Summary of Light-dependent
Reaction

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* Energy is captured from sunlight and
transferred to electrons(electron transport
chain).
Water molecule pulled apart to provide H
ions.
The ions are used to make ATP and
NADPH.
Need: sunlight and water
Produce: energy carrying molecules
and oxygen(waste).

Thylakoid
compartm
ent
(high H+)
The production of ATP
Lig
ht
Lig
ht
Thylakoid
membrane
Antenn
a
molecul
es
Stroma
(low H+)
ELECTRON
TRANSPORT
CHAIN
PHOTOSYSTEM
PHOTOSYSTE
II
MI
ATP
SYNTHASE
Summary—Light Dependent
Reactions
a. Overall input
light energy, H2O.
b. Overall output
ATP, NADPH, O2.
AN OVERVIEW OF PHOTOSYNTHESIS
• Step 2 – Light Independent Reaction – CALVIN
CYCLE Occurs in the stroma.
• The Calvin cycle makes sugar from carbon dioxide
1.ATP generated by the light reactions provides
the energy for sugar synthesis
2.The NADPH produced by the light reactions
provides the electrons for the reduction of
carbon dioxide to glucose. Carbon Dioxide is
built to make a 6 carbon sugar called glucose.
– END GOAL – to break carbon dioxide down and
combine into glucose!!! Need energy to do
this!! That is why ATP and NADPH was made!!
Light Independent Reaction Overview
1. Carbon dioxide added:Carbon Dioxide enters the
plant from the atmosphere. Bonds with a 5-carbon sugar.
2. Three-carbon molecules formed: ATP and NADPH
use enzymes in the stroma to split the six carbon into
3 carbon sugars.
3. Three-carbon molecules exit: Most 3 carbon stay in cycle.
When 2 leave, they form glucose.
4. Three-carbon molecules recycled: Energy from ATP
Change 3carbon molecules back into 5 carbon to start the
cycle over again.
*Energy provided by Light dependent reaction.
The plants uses the carbohydrates to meet its energy needs
to make all of the macromolecules that it needs(proteins, lipi
Overview Calvin Cycle
In put: ATP, NADPH, and Carbon dioxide
Output: GLUCOSE!!
The end goal – Make glucose from the SUN!!
Harvesting Chemical Energy
Energy enters food chains (via autotrophs) we can
look at how organisms use that energy to fuel
their bodies.
 Plants and animals both use products of
photosynthesis (glucose) for metabolic fuel
 Heterotrophs: must take in energy from outside
sources, cannot make their own e.g. animals
Cellular Respiration
RELEASES CHEMICAL ENERGY
FROM SUGARS AND OTHER
CARBON-BASED MOLECULES TO
MAKE ATP WHEN OXYGEN IS
PRESENT!!!!
NO OXYGEN – FERMENTATION!!!!
The Purpose of Cellular Respiration
It is to make and break bonds to generate ATP and
electrons.
You end up with ATP, H ions and electrons.
The electrons are sent to the Electron Transport Chain
where they help to make ATP through ATP synthase.
****Hydrogen ions are bonded with oxygen to make
water which is used in photosynthesis.
HOW DO WE MAKE ATP?
Just like in photosynthesis. ATP is made
by pumping H across ATP synthase to
attach a P onto ADP. This is the goal of
cellular respiration.
Relationship between Photosynthesis and Cellular
Respiration
The products on one are used for the other to
produce ATP from the Sun!
Creates the Carbon- Oxygen Cycle!!!
Carbon Oxygen Cycle
NADP and NAD
Photosynthesis use the electron carrier NADP
(nicotinmide adenine dinucleotide phosophate)
Cellular respiration uses - NAD
( nicotinmide adenine dinucleotide)
Cellular Respiration Overview
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Transformation of chemical energy in food into
chemical energy cells can use: ATP
These reactions proceed the same way in plants
and animals. Process is called cellular
respiration
Overall Reaction:
–
C6H12O6 + 6O2 → 6CO2 + 6H2O
Cellular Respiration
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Glycolysis – Occurs before Cell. Resp.
Krebs Cycle (Citric Acid Cycle)
Electron Transport Chain (ETC)
Glucose
Glycolysis
Krebs
cycle
Fermentation
(without oxygen)
Electron
transport
Alcohol or
lactic acid
Overall Reaction
C6H12O6 + 6O2 → 6CO2 + 6H2O + 38 ATP
Overall this is a three stage process
Glycolysis: before cellular respiration

1.
•
•
Occurs in the cytoplasm
Glucose is broken down
Krebs Cycle
2.
•
•
Breaks down pyruvate into CO2
Occurs in mitochondrial matrix
Electron Transport Chain
3.
•
ATP is synthesized - Occurs in mito membrane
Section 9-2
Flowchart
Cellular Respiration
Glucose
(C6H1206)
+
Oxygen
(02)
Glycolysis
Krebs
Cycle
Electron
Transport
Chain
Carbon
Dioxide
(CO2)
+
Water
(H2O)
+
ATP
Cellular Respiration Overview


Breakdown of glucose begins in the cytoplasm:
the liquid matrix inside the cell
After glycolysis, life diverges into two forms and
two pathways
–
–
Anaerobic cellular respiration (aka fermentation) No
oxygen
Aerobic cellular respiration I Oxygen needed!!
ANAEROBIC VS. AEROBIC
Anaerobic – no oxygen present
fermentation or lactic acid can be formed.
No oxygen then no cellular respiration.
Aerobic –oxygen present. If oxygen is
present , then cellular respiration can
occur.
Aerobic vs. Anaerobic
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Anaerobic DOES
NOT require oxygenfermentation
–
–
–
Simple
fast
produces smaller
amounts of energy
(ATP)

Aerobic requires
oxygen – cellular
respiration
–
–
Yields large
amounts of energy
What is this energy
molecule?
 ATP, ATP, ATP
Glycolysis
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Glyco = glucose
Lysis = break down
LOCATION: Occurs in the cytoplasm
This stage occurs in BOTH aerobic and
anaerobic respiration
Glucose breaks down into 2 pyruvate (2 ATP are
also made)
– Glucose is a 6-carbon sugar
– Pyruvate is a 3-carbon molecule (there are
two of them)
Steps of Glycolysis
1.Two ATP molecules are used to energize a
glucose molecule.
2. Glucose is split into 2 3 carbon molecules.
Enzymes rearrange the molecules.
3. Electrons are transferred to NADP. The
carbon molecules are converted to pyurate
which enters cellular respiration.
Glycolysis
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End Product: Breaks glucose into 2 –3 carbon
molecules called PYRUVIC ACID.
2 atoms of ATP are needed to breakdown this
molecule.
High energy electrons are passed to NAD to
form NADH(sent to ETC)
4 ATPS are synthesized and 2 are used for a net
gain of 2 ATPs.
Glycolysis
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Locatiom: Cytoplasm
NO O2 required
Energy Yield net gain of 2 ATP at the
expense of 2 ATP
6-C glucose  TWO 3-C pyruvates
Free e- and H+ combine with organic ion
carriers called NAD+  NADH + H+
(nicotinamide dinucleotide)Used in ETC.
Hydrogen attached to water.
Glycolysis:
Figure 9–3 Glycolysis
Step 1
Glucose
2 Pyruvic acid
To the electron
transport chain
Glycolysis Reactants and Products
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Reactants
1 glucose
Enzymes are needed
2 ATP are needed to start
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Products
2 Pyruvates (go to next
step)
4 ATP (2 are gained)
2 NADH (go to ETC)
Really 10 steps with 10 different enzymes
involved.
Main Goals of Krebs Cycle
Transfer high energy electrons(NADPH and
FADH) to molecules that can carry them to the
electron transport chain.
* Form some ATP molecules.

Section 9-2
Figure 9–6 The Krebs
Cycle
Citric Acid
Production
Mitochondrion
Krebs Cycle- MATRIX

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Pyruvic acid(3carbon) enters mitochondria. In
the innermost layer of mitochondria or the
MATRIX pyruvic acid are broken down into
carbon dioxide and acteyl CoA molecules.
Acetyl- CoA combines with 4 carbon compounds
forming a 6 carbon molecule citric acid. Energy
is released by breaking and reforming these
bonds.
Kreb Cycle
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1. Pyruvate broken down
2. Coenzyme A bonds to 2 carbon molecule
3. Citric Acid formed: 2 carbon bonded to 4
carbon. Coenzyme goes back to step 2.
4. Citric Acid brokendown: into 5 carbon sugar
carbon dioxide and NADH
5. 5 carbon sugar broken down: Into 4 carbon
sugar, NADH, ATP and Carbon dioxide.
6. 4 carbon rearranged by enzymes. Molecules
of NADH, FADH(electron carrier).
Second Step: Citric Acid Cycle (Krebs
Cycle)
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Where Mitochondrial matrix
Energy Yield 2 ATP and more eAcetyl-CoA (2-C) combines with 4-C to form
6-C CITRIC ACID
Citric Acid (6-C) changed to 5-C then to a 4-C
Gives off a CO2 molecule
NAD+ and FAD pick up the released eFAD becomes FADH2
NAD+ becomes NADH + H+
Cycle ALWAYS reforming a 4-C molecule
Krebs Cycle Reactants and Products

Reactants
2 Acetyl CoA
Products
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Remember when you
form a bond energy is
released!! This is the key!!
2 ATP
6 NADH (go to ETC)
2 FADH2 (go to ETC)
4 CO2 (given off as
waste)
Products of Kreb Cycle
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High energy carriers – NADH and FADH – This
is the main goal!!!
Carbon Dioxide
2 ATP molecules
4 carbon molecules to start again
HYDROGEN IONS ARE SENT DOWN THE
ELECTRON TRANSPORT CHAIN to make ATP.
Krebs Cycle
Electron Transport
ATP synthesis
Electron Transport Chain
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Where inner membrane of mitochondria called
cristea.
Energy Yield Total of 32 ATP
O2 combines with TWO H+ to form H2O
Exhale - CO2, H2O comes from cellular
respiration
Electron Transport - Step 3
1. Proteins inside the membrane of the mito.
Remove electrons from NADPh and FADH.
2. Electrons(hydrogen) are transported down the
chain of the membrane to be pumped across.
3. ATP synthase(enzyme) puts a P on ADP to
make ATP(END GOAL!!).
4. Oxygen enters the cycle to pick up electrons and
hydrogen ions to make water that leaves the
cycle.
Electron Transport Chain
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Electron carriers loaded with electrons and
protons from the Kreb’s cycle move to this chainlike a series of steps (staircase).
As electrons drop down stairs, energy released
to form a total of 32 ATP – Final Goal!!
Oxygen waits at bottom of staircase, picks up
electrons and protons and in doing so becomes
water
Electron Transport Chain

Occurs in the cristae of the mitochondria
Electron Transport Chain
Section 9-2
Electron Transport
Hydrogen Ion Movement
Channel
Mitochondrion
Intermembrane
Space
ATP synthase
Inner
Membrane
Matrix
ATP Production
Photosynthesis
What happens to the glucose formed in photosynthesis?
PHOTOSYNTHESIS
CELLULOSE
LIPIDS
GLUCOSE
respiration
ATP
Required to make plant cell walls. It is made
of 100s of glucose molecules bonded
together.
Glucose is chemically converted to fatty acids and
glycerol to make lipids, which are needed to make
plant cell membranes and seed storage oils.
STARCH
Is used by roots and leaves to store excess
glucose in an osmotically inactive form. It is
made of 100s of glucose molecules.
PROTEINS
Using nitrate ions absorbed by plant roots,
glucose is converted first to amino acids
then to protein.
CARBON
DIOXIDE AND
WATER
The carbon dioxide can be used again in
photosynthesis or may diffuse out of the
leaf via the stomata
Anaerobic Cellular Respiration

Some organisms thrive in environments with little or no
oxygen
–
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Marshes, bogs, gut of animals, sewage treatment ponds
No oxygen used= ‘an’aerobic
Results in no more ATP, final steps in these pathways
serve ONLY to regenerate NAD+ so it can return to pick
up more electrons and hydrogens in glycolysis.
End products such as ethanol and CO2 (single cell fungi
(yeast) in beer/bread) or lactic acid (muscle cells)
Two Types of Fermentation
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Alcoholic Fermentation
Pyruvate converted to
ethyl alcohol and CO2
Carried out by yeast and
some bacteria
Used in producing alcohol
(both consumable and for
ethanol), and for baking

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Lactic Acid Fermentation
Pyruvate converted to
lactic acid
Carried out by muscles
when working hard
(muscles need ATP but
can’t get O2 )
Causes muscle soreness
and cramps
Alcohol Fermentation

Pyruvate
C6H12O6 → 2 C2H5OH + 2CO2 + 2 ATP
quation
Sugar (glucose) → Alcohol (ethanol) + Carbon Dioxide + Energy (ATP)
Alcoholic Fermentation
C6H12O6
(Ethyl Alcohol
or Ethanol)
2 C2H5OH + 2 CO2
As a result of Alcoholic
Fermentation,
Glucose is converted into 2
molecules of Ethyl Alcohol and 2
Molecules of Carbon Dioxide.
Importance of Fermentation

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Alcohol Industry - almost every society has a
fermented beverage.
Baking Industry - many breads use yeast to
provide bubbles to raise the dough.
Alcoholic Fermentation

Bacteria and fungi (yeast)

Ethyl alcohol and carbon dioxide are
the end products

Process used to form beer, wine, and
other alcoholic beverages
Also used to raise dough, bread

Lactic Acid Fermentation
Uses only Glycolysis.
 Does NOT require O2
 Produces ATP when O2 is not
available.

Lactic Acid Fermentation
Carried out by human muscle cells under
oxygen debt.
 Lactic Acid is a toxin and causes fatigue,
soreness and stiffness in muscles.

Lactic Acid Formation

pyruvate + NADH----- lactic acid + NAD+
Lactic Glycolysis
Acid Fermentation
4 ATP’s are
produced
Pyruvic Acid (3C)
Lactic Acid (3C)
Pyruvic Acid (3C)
Lactic Acid (3C)
Glucose
(6 carbons)
2 ATP’s supply the
activation energy
2 NAD+ + 2 e-
2 NADH
2 NAD+ + 2 e-
4 ATP Yield = 2 ATP Net Gain
Fermentation - Summary


Releases 2 ATP from the breakdown of a
glucose molecule
Provides ATP to a cell even when O2 is
absent.
Energy Tally

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36 ATP for aerobic vs. 2 ATP for anaerobic
–
Glycolysis
2 ATP
–
Kreb’s
2 ATP
–
Electron Transport
32 ATP
36 ATP
Anaerobic organisms can’t be too energetic but
are important for global recycling of carbon