Transcript Photosynthesis

Photosynthesis
Why it’s Important for
Biological Energy
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Overview
• Biology: Study of Living Things
– Includes: Plants, Animals, Bacteria etc.
• All energy on earth comes from the sun.
• We depend on:
– Plants
– Algae (underwater plants)
– Cyanobacteria (photosynthetic bacteria)
• To provide this energy to us!
Overview
• Carbon dioxide and water are taken in
by plants
• Plants absorb light energy and convert
it to a usable form.
– ATP
• Energy is used to “fix” carbon dioxide
into sugar molecules
– Chemical energy
• Sugar is converted to starch and stored
for use by the plant, and by animals
when they eat plants.
Chloroplasts
• All light energy is
transformed into
sugar (chemical
energy) in the
chloroplasts….
The green part of
the leaf.
Image source: http://www.daviddarling.info/encyclopedia/C/chloroplasts.html
Chloroplasts
• Chlorophyll molecules
are embedded in the
thylakoid membrane
• Act like a light “antenna”
• These molecules can
absorb sunlight energy.
Image from Biology 11: College Preparation. Pg 73. Nelson,
Toronto. 2003.
Light (dependent)Reactions
•
Happen ONLY in
sunlight
– Hence they depend
on light!
1. Light is absorbed
by chlorophyll
molecules
2. The energy
generates
molecules of ATP
Image from: Biology 11: College Preparation. Pg 74. Nelson, Toronto. 2003.
Overall Reaction
What is the equation for photosynthesis?
carbon dioxide + water  glucose + oxygen +
energy
6CO2 + 6H2O  C6H12O6 + 6O2 + energy
Summary
Image from: Biology 11: College Preparation. Pg 74. Nelson, Toronto. 2003.
Why do leaves turn brown in
the fall?
• It’s all about pigments!
• Write a short description of why you
think they turn brown and fall off.
• If you wrote that Leaves turn brown and
fall off because photosynthesis does not
occur efficiently in the winter with less
sunlight, so the tree is trying to save up
energy by holding chlorophyll in the tree
trunk and not in the leaves…. Then
you’re right!
What is Respiration?
• Respiration is the opposite of
photosynthesis.
• It’s how we and all other animals receive
energy.
• Glucose + Oxygen = Carbon Dioxide +
Water + Energy
• C6H12O6+6O2=6CO2+6H2O+Energy
The Energy is in the form of ATP.
Structure of ATP
adenosine
Pi
Pi
Pi
Formation of ATP
ATP is made when another molecule
called adenosine diphosphate (ADP) is
bonded to a third inorganic phosphate
(Pi) using the energy released from
glucose.
Energy from respiration
adenosine
Pi
Pi
+
Pi
Enzymes
adenosine
Pi
Pi
Pi
Energy Rich bond formed
Summary
ATP
ATP
cellular
respiration
cellular
respiration
energy
(out)
energy
(in)
energy
(out)
cell
cell
activities
activities
ADP + Pi
The whole process is an enzyme controlled reaction.
ATP production – summary
glucose
2 ADP + 2 Pi =
2 ATP
pyruvic acid
36 ADP + 36 Pi =
36 ATP
carbon dioxide + water