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PHOTOSYNTHESIS &
CELLULAR RESPIRATION
REMEMBER…CHARACTERISTICS OF
LIVING THINGS
made up of units called cells
reproduce
based on a universal genetic code (DNA)
grow and develop
obtain and use materials and energy (metabolism)
respond to their environment (adapt)
maintain a stable internal environment (homeostasis)
taken as a group, organisms evolve
ENERGY AND LIFE
ENERGY
Energy: the ability to do work
Living things must be able to obtain and use
energy in order to exist.
ATP (adenosine triphosphate) – chemical
compound that living things use to store energy
CHEMICAL
ENERGY
&
ATP
ATP is made of adenine, ribose
(sugar), and 3 phosphate groups.
Energy is stored in bonds between
the phosphate groups.
When a cell needs energy, one of
the phosphates is removed (leaving
ADP or adenosine di-phosphate).
Energy that had been stored in
the bond can now be used by the
cell.
ATP can be compared to a rechargeable
battery.
ATP
• Charged battery
ADP
• Partially charged battery (needs charging)
ATP AND GLUCOSE (C6H12O6)
Most cells have only a small amount of ATP
• Lasts for a few seconds of activity
• Efficient at transferring energy but not for storing energy over a
long term
A single sugar molecule stores more than 90 times the
energy of 1 molecule of ATP!
Cells can regenerate ATP from ADP as needed by using
the energy in carbohydrates like glucose
SO…WHERE DO LIVING THINGS
GET ENERGY?
FOOD
• To live, all organisms need
food and must release
energy from that food.
SO…HOW DO LIVING THINGS GET
FOOD?
Autotrophs
Organisms that make their own food
through photosynthesis (AKA:
producer)
Heterotrophs
Organisms that consume or eat
food (AKA: consumer)
Examples: plants, some protists,
certain bacteria
Chemosynthesis: process by which
ATP is synthesized by chemicals as
an energy source instead of light
Examples: animals, fungi, some
bacteria, some protists
PHOTOSYNTHESIS:
AN OVERVIEW
PHOTOSYNTHESIS…
PLANTS, ALGAE, AND SOME BACTERIA
Reactants
Products
Light energy is
converted into
chemical energy!
PHOTOSYNTHESIS EQUATION
• Photosynthesis: a process that uses the
energy of sunlight to convert water and
carbon dioxide into glucose and oxygen
6CO2 + 6H2O
(carbon dioxide)
(water)
sunlight
C6H12O6 + 6O2
(glucose)
(oxygen)
THE REACTIONS OF
PHOTOSYNTHESIS
INSIDE A CHLOROPLAST
Photosynthesis takes place within
chloroplasts.
Thylakoid membranes (labeled B) – saclike
membranes in the chloroplasts that contain
chlorophyll to capture energy from the sun
Light dependant reactions take place within
the thylakoids.
Stroma (labeled A) – fluid outside the
thylakoid membranes
Light independent reactions (Calvin Cycle)
takes place within the stroma.
REACTIONS OF
PHOTOSYNTHESIS
:
LIGHT DEPENDENT
REACTIONS
Requires water and light
which is captured by the
chlorophyll
Converts ADP and NADP+
into ATP and NADPH
which are energy carriers
needed to provide energy
for the Calvin Cycle
Releases oxygen as waste
light
carbon dioxide
water
6 carbon sugar: glucose
oxygen gas
THE SECOND STAGE OF
PHOTOSYNTHESIS USES
ENERGY FROM THE FIRST
STAGE TO MAKE SUGARS
REACTIONS OF
PHOTOSYNTHESIS:
Requires energy from
ATP and NADPH
produced during the light
dependent reaction
CALVIN CYCLE OR LIGHTINDEPENDENT REACTIONS
Converts carbon dioxide
into glucose
Regenerates ADP and
NADP+ which go back to
the light-dependent
reactions for re-charging
OVERVIEW OF THE LIGHTINDEPENDENT REACTIONS
light
carbon dioxide
water
glucose
oxygen gas
FACTORS AFFECTING
PHOTOSYNTHESIS
• photosynthesis occurs best
between 0C and 35C; above
or below this temp the
enzymes that control
photosynthesis are affected
so photosynthesis slows
down
Temperature
Water
• photosynthesis requires
water so low water
availability would slow down
the rate of photosynthesis
• more light would speed up
the rate of photosynthesis;
eventually the rate reaches a
maximum rate that it cannot
exceed
Light
FUNCTIONS OF
PHOTOSYNTHESIS
Removes CO2
from the
atmosphere
Provides
materials for
plant growth
and
development
Does more
than make
sugars!
HOW WE CAME TO
UNDERSTAND
PHOTOSYNTHESIS
THE QUESTION:
HOW DOES A TREE INCREASE ITS
MASS?
FROM THE SOIL?
FROM THE WATER?
FROM THE AIR?
VAN HELMONT’S EXPERIMENT
(1643)
• Concluded
that it was
water!!
PRIESTLEY’S EXPERIMENT (1771)
• Candle burned in the presence of oxygen
• A candle could be relit near a plant and it
would burn longer because the plant
released oxygen
INGENHOUSZ’S EXPERIMENT
(1779)
• Showed Priestley’s experiment only
worked when the plant was exposed to
light
• Light is necessary for
plants to produce oxygen
PHOTOSYNTHESIS
COMPLETED!
BUT WAIT…
HOW DO LEAVES CHANGE
COLOR?
ABSORPTION OF LIGHT ENERGY
• Light energy is a form of radiation
• Energy in the form of waves that travel
through space
• Different types of radiation (i.e. light,
heat) have different wavelengths
Pigment
A light-absorbing
substance that gives
another substance or
mixture its color
Absorbs certain
wavelengths and reflect
others
Chlorophyll
Carotenoid
Green Pigment
A pigment that absorbs
mostly blue and green
light
Absorbs violets, blues
and reds and reflects
greens and yellows
Therefore it produces
yellow and orange fall leaf
colors
Therefore plants exhibit
green and yellow colors
Color of many fruits,
vegetables and flowers
LEAF COLOR COMES FROM
PIGMENTS
• Chlorophyll (green)
• Carotenoid (yellow, orange, and brown)
• Anthocyanins (red)
• Chlorophyll covers the carotenoid -- that's why
summer leaves are green, not yellow or orange
• Trees respond to the decreasing amount of sunlight in
the fall by producing less and less chlorophyll
LEAF COLOR COMES FROM
PIGMENTS
• Eventually, a tree stops producing
chlorophyll
• When that happens, the carotenoid already
in the leaves can finally show through
• The leaves become a bright rainbow of
glowing yellows, sparkling oranges and warm
browns
PART II
CELLULAR RESPIRATION
IS LIKE
A MIRROR OF
PHOTOSYNTHESIS
CELLULAR RESPIRATION
Reactants
Products
CELLULAR
RESPIRATION
MAKES ATP BY
BREAKING
DOWN
SUGARS
CHEMICAL ENERGY AND FOOD
Food provides cells with energy and serves as raw
materials for building new molecules.
How do organisms get the energy from their food?
Cells release energy from glucose and other food
compounds by the processes of cellular respiration,
fermentation, or both.
CELLULAR RESPIRATION
enzymes
Glucose
oxygen gas
carbon dioxide
water
ATP
OVERVIEW OF
ENERGY RELEASING PROCESSES
Cellular Respiration
Fermentation
a process that
produces energy
(ATP) by breaking
down food
molecules in the
presence of oxygen
a process that
produces energy
(ATP) by breaking
down food
molecules in the
absence of oxygen
GLYCOLYSIS
The first process cells use
to break down food and
release energy.
Occurs in the cytoplasm
and breaks glucose in half
into 2 pyruvic acid
molecules creating 2 ATPs.
CELLULAR RESPIRATION
When oxygen is present, products of glycolysis enter Krebs
Cycle and electron transport chain (in mitochondria).
36 ATPs produced during cellular respiration.
Carbon dioxide and water are waste.
FERMENTATION
When oxygen is NOT present, products of glycolysis go
through fermentation instead.
Fermentation regenerates starting materials of glycolysis
so glycolysis can continue making ATP (only 2 ATPs).
Alcoholic fermentation
Lactic acid fermentation
ALCOHOLIC VS. LACTIC ACID
FERMENTATION
Alcoholic
Fermentation
Lactic Acid
Fermentation
performed by yeast and
other microorganisms
occurs in muscle cells
during strenuous exercise
when cells aren’t getting
enough oxygen
used in bread and alcohol
industries because alcohol
and carbon dioxide are
waste products
lactic acid produced as a
waste product causes
muscles to burn during a
strenuous workout
COMPARING PHOTOSYNTHESIS & CELLULAR RESPIRATION
Photosynthesis
Cellular Respiration
Function
to store energy by
making food
to release energy by
breaking down food
Location
Chloroplasts
Mitochondria
Carbon Dioxide +
Water + Sunlight
Glucose + Oxygen
Products
Glucose + Oxygen
Carbon Dioxide +
Water + Energy
Equation
6H2O + 6CO2
C6H12O6 + 6O2
C6H12O6 + 6O2
6H2O + 6CO2
autotrophs
autotrophs and
heterotrophs
Reactants
Organisms
THE CYCLE OF MATTER AND
ENERGY
sunlight
CO2 + H2O
Photosynthesis and
Cellular Respiration
work together to cycle
matter and energy
O2 + C6H12O6
ATP
REMEMBER…CHARACTERISTICS OF
LIVING THINGS
made up of units called cells
reproduce
based on a universal genetic code (DNA)
grow and develop
obtain and use materials and energy (metabolism)
respond to their environment (adapt)
maintain a stable internal environment (homeostasis)
taken as a group, organisms evolve