ENERGY OF LIFE
Photosynthesis & ATP
Characteristics of Living Things
Made of
Cells
DNA
Obtain and
Use Energy
& Materials
Grow &
Develop
Evolve
Reproduce
(Change Over Time)
Respond to
Stimuli
Maintain
Homeostasis
Energy
3
Has many forms:
light, heat, electrical,
chemical, mechanical, kinetic
 Law of Conservation of Energy

 Energy
can neither be created nor
destroyed, but can be converted
from one form to another.
Living things are classified based on
how they obtain energy

Autotrophs – Organisms that make their own food.
 Photosynthesis
is the process by which plants use
the sun’s energy to make sugar (glucose) for food.
 Chemosynthesis is the process by which food
(glucose) is made by bacteria using chemicals as the
energy source, rather than sunlight.

Heterotrophs – Organisms that consume other living
things.
Life Evolved Before Photosynthesis, so first
life forms were chemosynthetic



During chemosynthesis,
bacteria use energy
stored in the chemical
bonds of hydrogen
sulfide and methane to
make glucose from
water and carbon
dioxide.
Occurs in hydrothermal
vents deep in the ocean
and methane seeps.
Typical environments on
early Earth
First Life Forms on Earth


Still a mystery how life came to be on Earth. There
are several theories.
First life was simple
 Small
 Anaerobic
 Single
celled
 Prokaryotic Bacteria and Archea
 Chemosynthetic
Prokaryotic Cells


No nucleus
No membrane bound organelles
Questions to answer
1.
2.
3.
4.
How many billions of years ago did photosynthesis
evolve?
Which type of microbe was the first to develop
photosynthesis?
What was the “Great Oxygenation Event”? How
long ago was it?
Explain how plants became photosynthetic.
Evolution of Photosynthesis and
Oxygenation of the Atmosphere
Origin of the Chloroplast



1.8 billion years ago
Developed through endosymbiosis
Cyanobacteria were engulfed by an aerobic
eukaryotic cell.
Great Oxygenation Event – 2.5 bya



Photosynthetic cyanobacteria
Cyanobacteria colonies formed stromatolites – mats
of cyanobacteria and other microbes trapped and
bound with sediments
38-44 Origins
Atmosphere 3



Main Gases: Nitrogen (N2) – 78%, Oxygen (O2)21%, Carbon Dioxide <1%
Source of Gases: Oxygen from photosynthetic
organisms, carbon dioxide from respiration and
burning of fossil fuels. Nitrogen from break up of
ammonia gases from volcanic outgassing.
Description: Plants and animals are in balance.
Plants take in carbon dioxide and give off oxygen.
Animals take in oxygen and give off carbon
dioxide. Original oxygen from cyanobacteria.
How do heterotrophs get energy?



Eat other organisms
Breakdown their macromolecules to release energy
Main process: Cellular Respiration
What are you? Autotroph or Heterotroph?
Your body is hard at work, right now!



It is trying to maintain homeostasis and keep you
alive
But, where is all of the energy for all of that work
coming from?
How does your body store energy and release it
when it is needed?
 What
form is that energy in?
ATP – Cellular Energy
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


Adenosine Triphosphate
Main source of energy in living things
Made of a nitrogen base (adenine), a sugar
(ribose) and 3 phosphate groups.
Releasing Energy From ATP
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ATP is constantly being used and
remade by cells
 ATP releases energy when the high
energy phosphate bond is BROKEN

ADP
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•
•
Adenosine Diphosphate – 1 less phosphate group
ATP releases energy, a free phosphate, & ADP
when cells take energy from ATP
One phosphate bond has been removed
Cells Using Biochemical Energy
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Cells Use ATP For:
 Active transport
 Movement
 Photosynthesis
 Protein Synthesis
 Cellular respiration
 All other cellular reactions
Glucose
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
In photosynthesis, plants make glucose
using the sun’s energy, carbon dioxide
and water.
 They
transform solar energy into chemical
energy in the form of glucose.
 Glucose is a sugar (carbohydrate).
 C6H12O6

In cellular respiration, energy in glucose
is transformed into ATP.
ENERGY OF LIGHT
Electromagnetic Radiation – A type of energy
If something is green, does it absorb
green light or reflect green light?
Green things absorb all colors except green. Green is
reflected.
 What about something that is black?
 Absorbs

all colors.
What about something that is white?
 Reflects
all colors.
Light & Pigments
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Different pigments absorb different
wavelengths of light
 Light “excites” electrons in the plant’s
pigments
 Excited electrons carry the absorbed
energy

Pigments in Plants
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•
•
•
Chlorophyll is the primary lightabsorbing pigment in plants.
Chlorophyll is found inside chloroplasts
Chlorophyll absorbs red & blue light
and REFLECTS GREEN
Plant Pigments
25

There are other pigments in plants:


Carotenoid (reflects orange)
Xanthophyll (reflects yellow)
Fall Colors
26
Photosynthesis
Photosynthesis
28

In photosynthesis, Light Energy
converts Water (H20) and Carbon
Dioxide (CO2) into Oxygen (O2) and
glucose (C6H12O6)
It begins with sunlight!
29
The chloroplasts in plants
Inside
A Chloroplast
absorbs light
energy. Draw
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and label a chloroplast.
Structure of the Chloroplast
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Double membrane organelle
 Outer membrane smooth
 Inner membrane forms stacks of
connected sacs called thylakoids
 Thylakoid stack is called the granun
(grana-plural)
 Gel-like material around grana called
stroma

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Light Dependent Reaction
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Light Dependent Reactions


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Location: Thylakoid membrane of the chloroplast
Inputs: H20, ADP, NADP+ (Light)
Outputs: O2, NADPH, ATP
Summary:
Light-absorbing pigments in the chloroplast absorb sunlight
and generate high-energy electrons that are passed down
an electron transport chain to make ATP energy and NADPH
(electron carrier). Oxygen is released as a byproduct.
 The ATP and NADPH are sent to the second part of
photosynthesis: The Calvin Cycle or Light Independent
Reactions

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Electron Carriers


High energy electrons are highly reactive, in order
to move them around the cell, they need a carrier.
An electron carrier is a compound that can accept a
pair of high-energy electrons and transfer them,
along with most of their energy, to another
molecule.
 NADP+
is an electron carrier, it accepts two highenergy electrons and a H+ which converts it to NADPH.
It carries these electrons and ions from the light
dependent to the light independent reactions.
Light Independent Reactions = Calvin
Cylce


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Location: Stroma of chloroplast
Inputs: CO2, NADPH, ATP
Outputs: Glucose, ADP, NADP+
Summary:
NADPH and ATP produced during the light dependent
reactions are used to produce high energy sugars from
carbon dioxide.
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The Calvin Cycle
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Factors Affecting the Rate of
Photosynthesis
40
Amount of
available water
 Temperature
 Amount of
available light
energy
 Amount of CO2
