Photosynthesis
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Takes place in the chloroplasts of plant cells
Organisms that can perform photosynthesis are called “autotrophs” – they
produce their own food.
Overall reaction: CO2 + H2O + Sunlight  O2 + C6H12O6
Can be split into 2 parts
Light Reaction
 Needs light energy and water to proceed
 Produces O2
 Also produces temporary energy storage molecules – ATP and NADPH.
These are used to provide energy for dark cycle
Dark Reaction
 Does NOT need light energy to proceed
 Needs CO2 and water to proceed
 CO2 comes into leaves via pores in leaves call “stomata”
 Enzyme called “Rubisco” catalyzes the process
 Also called “Calvin Cycle”
 Produces long-term energy storage molecule - Glucose
 Passes ADP (product of stripping energy from ATP) and NADP+ (product of
stripping energy from NADPH) back to Light Reaction
PHOTOSYNTHESIS – Light and
Dark Reactions
Respiration
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Inputs are O2 and Glucose
Produces CO2 and H2O
Also produces lots of ATP (up to 40 molecules of ATP per molecule of
Glucose)
Respiration is done by both “heterotrophs” (organisms that cannot produce
their own food, such as fungi and animals) and “autotrophs” (organisms that
produce their own food).
Overall reaction (for aerobic respiration):
O2 + C6H12O6  CO2 + H2O + Energy
Can be split into two parts
Glycolysis
 Takes place in the cytoplasm of cells
 Each Glucose molecule is broken down into two “pyruvic acid” molecules
 Produces overall 2 molecules of ATP and 2 molecules of NADH (ATP and
NADH are temporary energy storage molecules)
 Does NOT require O2 and does NOT produce much energy.
Aerobic Respiration
 Takes place in mitochondria
 Pyruvic acid is broken down into CO2 and H2O
 This process is called the “Krebs Cycle”
 Can produce up to 38 ATP
 Requires O2 and DOES produce lots of energy
Fermentation
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Called “Anaerobic Respiration” because doesn’t require O2
Done by prokaryotes (since they don’t have mitochondria)
Done by eukaryotes in the absence of O2
Consists of Glycolysis and then the regeneration of NAD+ from NADH
Two types of fermentation – one type produces alcohol, one type produces
lactic acid
Alcohol Fermentation – how we make beer and wine
Lactic acid build-up in muscles – results from anaerobic respiration during
exercise – the “burn” in your muscles
How are Photosynthesis and Respiration
Related?
Outputs of Photosynthesis are the Inputs of Respiration
Outputs of Respiration are the Inputs of Photosynthesis
Vocabulary – Define the following terms
Photosynthesis –
A process in which plants use energy from light to produce
glucose and oxygen from carbon dioxide and water
Carbon Dioxide Gas –
A colorless, odorless gas that is produced during
respiration.
Oxygen Gas –
Chemical formula is CO2
A colorless, odorless gas that is used during aerobic
respiration.
Produced by photosynthesis.
Chemical formula
is O2
Glucose –
a simple sugar that serves as the major energy source for
all cellular processes. The chemical formula of glucose is
C6H12O6.
Electromagnetic EnergyVisible Light is a form of electromagnetic energy, with
wavelengths between 400-700 nm.
Light Reaction
The reaction in the thylakoid membranes of chloroplasts
that absorbs light energy and produces oxygen gas, NADPH
and ATP
Dark Reaction
The reaction in the stroma of chloroplasts that takes in
CO2 and produces glucose.
Calvin Cycle
Another name for “Dark Reaction”
ATP
Adenosine Tri-Phosphate.
A temporary energy storage
molecule that provides energy for cellular processes.
ADP
Adenosine Di-Phosphate.
The energy depleted form of ATP.
NADPH
nicotinamide adenine dinucleotide phosphate-oxidase – A
temporary energy storage molecule used in photosynthesis.
NADP+
Nicotinamide adenine dinucleotide phosphate – The energy
depleted form of NADPH
NADH
Nicotinamide adenine dinucleotide – A temporary energy
storage molecule which is used in cellular respiration
NAD+
The energy depleted from of NADH
Glycolysis
The 1st step of cellular respiration –
a process in the
cytoplasm that converts [[glucose] C6H12O6, into pyruvate,
Pyruvic Acid
A 3 carbon organic acid produced during glycolysis.
to fermentation and aerobic respiration
Pyruvate
For the purposes of this class, an alternate name for
pyruvic acid.
Krebs Cycle
Input
a series of enzyme-catalysed chemical reactions, which is
of central importance in all living cells that use oxygen
as part of cellular respiration. Also known as the citric
acid cycle.
Produces up to 38 ATP
Aerobic Respiration
Same as Krebs cycle
Anaerobic Respiration
Glycolysis + Fermentation.
require oxygen.
Respiration that does not
Produces 2 ATP
Fermentation
The process of anaerobic respiration. There are two types –
alcohol fermentation and lactic acid fermentation.
Questions:
Compare and Contrast Photosynthesis and Respiration:
Photosynthesis
Respiration
Inputs:
CO2 , H2O and sunlight
Inputs:
O2 and glucose
Steps:
Steps:
Glycolysis followed by
Light reaction and Dark
Reaction
Outputs:
O2 and Glucose
Where does it happen?:
In chloroplasts
What kind of organism does it?:
Autotrophs (plants and
photosynthetic bacteria)
fermentation or aerobic
respiration
Outputs:
CO2 and H2O and energy
Where does it happen?
In cytoplasm and mitochondria
What kind of organism does it?
Autotrophs and heterotrophs
Photosynthesis and Respiration – How are they Related?
Photosynthesis stores energy.
Respiration releases energy.
The outputs of photosynthesis are the inputs of respiration
and vice versa.
When does fermentation take place?
In low O2 or now O2 or in prokaryotes
Which produces more energy, fermentation or aerobic respiration?
Aerobic respiration
What is the relationship between ATP and ADP? What is the relationship
between NADPH and NADP+? What is the relationship between NADH and
NAD+?
They are all temporary energy storage molecules.
ATP is the energy rich form. ADP is the energy poor form.
NADPH is the energy rich form.
NADP+ is the energy poor
form.
NADH is the energy rich form.
NAD+ is the energy poor form
In your opinion, could life as we know it exist without photosynthesis? Why or
why not?
If there were no photosynthesis, then the only kind of
respiration that could be done would be anaerobic
respiration.
This form of respiration does not produce
much energy in the form of ATP.
It can support only very
simple forms of life that do not have high energy needs,
such as bacteria.
If there were no photosynthesis, only
very simple life would exist – not larger organisms that
require lots of energy, such as animals and plants.
What molecules do plants use for short-term energy storage? What molecules
do plants use for longer-term energy storage?
ATP, NADPH and NADH are short term energy storage
molecules.
Glucose and starch are longer-term energy storage
molecules.
What is an autotroph? Give an example.
An autotroph is an organism that produces its own food,
e.g. a plant
What is a heterotroph? Give an example.
A heterotroph is an organism that must ingest food to
provide energy for its metabolic processes, e.g. an animal
or a fungus
Sketch the energy flow of the heterotrophs, the sun, and autotrophs.
Sun  autotrophs  heterotrophs