ATP

Adenosine Triphosphate (ATP) - One of the
principal chemical compounds that living
things use to store and release energy
ATP

Made up of:
1.
2.
3.
Adenine
5-carbon sugar called ribose
Three phosphate groups (The key to ATP's ability
to store and release energy.)
ATP vs. ADP



Adenosine Diphosphate – ATP minus one
phosphate group
ATP – contains three phosphate groups
(tri = three)
ADP – contains two phosphate groups
(di = two)
Adenosine Triphosphate
Adenosine Diphosphate
ATP and Energy


ATP is used by all types of cells as their basic
energy source.
Energy is released when a phosphate is
removed.
Heterotroph

Heterotroph - Organism that obtains energy
from the foods it consumes; also called a
consumer
Autotroph

Autotroph - Organism that can capture energy
from sunlight or chemicals and use it to
produce its own food from inorganic
compounds; also called a producer.
Photosynthesis
Which organisms go through
Photosynthesis?

Plants
Photosynthetic Bacteria
(ex. Cyanobacteria)
Some Protists
(ex. Algae)
Photosynthesis

Photosynthesis - Process by which plants and
some other organisms use light energy to
convert water and carbon dioxide into oxygen
and high-energy carbohydrates such as sugars
and starches.
Photosynthesis

Needed (Reactants):
1.
2.
3.

Light
Water
Carbon dioxide
Given Off (Products):
1.
2.
Sugars
Oxygen
Chlorophyll


Photosynthesis also
requires chlorophyll, a
molecule located in
chloroplasts.
Chlorophyll - Principal
pigment of plants and
other photosynthetic
organisms; captures
light energy
Chlorophyll


Plants gather the sun's energy with lightabsorbing molecules called pigments.
The plants' principal pigments are called
chlorophyll.

Chlorophyll does not absorb light well in the green
region of the spectrum therefore green light is
reflected by leaves (this is why plants look green).
Chloroplast Vocabulary


Thylakoids - Saclike photosynthetic membrane
found in chloroplasts. (where chlorophyll is
found)
Stroma - Region outside the thylakoid
membranes in chloroplasts
Two Sets of Reactions in
Photosynthesis
2.
The Light-Dependent Reactions
The Light-Independent Reactions (akaCalvin Cycle)

These two chemical reactions work together!
1.
Light-Dependent Reactions




Takes place within the thylakoid membranes
Requires light
Requires: Water, ADP, and NADP+
Produce: Oxygen, ATP, and NADPH
Electron Carriers within the Light
Dependent reaction
1. Chlorophyll (in the Thylakoid membrane)
absorbs energy from sunlight and energized
electrons enter the electron transport chain.
2. Water molecules are broken down. Oxygen
is released as waste and electrons enter
chlorophyll.
3. Energy from electrons in the transport chain
is used to pump hydrogens ions across the
thylakoid membrane
Electron Carriers within the Light
Dependent reaction
4. More energy is absorbed and transferred to
electrons
5. Energized electrons leave the electron
transport chain and are used to produce
NADPH
6. Hydrogen ions flow through a channel
coupled to ATP synthase.
7. ATP synthase produces ATP.
Light Dependent Reactions

The sunlight breaks each water molecule into :



electrons
H+ ions (released into thylakoid membrane)
Oxygen atoms (released into the air)
Light Dependent Reactions

As electrons are passed from chlorophyll to
NADP+, more hydrogen ions are pumped
across the membrane.



Inside of the membrane fills up with positively
charged hydrogen ions.
Outside of thylakoid membrane becomes
negatively charged.
The difference in charges across the membrane
provides the energy to make ATP. The H+ ions
are important!
Light Dependent Reactions

ATP Synthase - Large protein/enzyme that
uses energy from H+ ions to bind ADP and a
phosphate group together to produce ATP.


Spans the thylakoid membrane and allows H+ ions
to pass through it.
Overall: Produce oxygen gas and convert ADP
and NADP+ into the energy carriers ATP and
NADPH.
The Light-Independent Reactions
(Calvin Cycle)



Takes place in the stroma
Requires: ATP, NADPH from the lightdependent reaction. Also CO2
Produces: high-energy sugars.
Calvin Cycle
1. Carbon dioxide added to the Calvin cycle.
2. Energy is used to split six CO2 molecules.
Three carbon molecules are formed and
rearranged.
A. three-carbon molecule exits the cycle.
Other three-carbon molecules stay in the
cycle.
Calvin Cycle
3. When two three-carbon molecules have left
the cycle, the bond to form a six-carbon sugar
4. Energy is used to convert the remaining
three-carbon molecules into five-carbon
molecules.
Factors Affecting Photosynthesis
1.
Water

2.
Temperature

3.
A shortage of water can slow or even stop
photosynthesis.
Photosynthesis depends on enzymes that function
best between 0°C and 35°C.
Intensity of Light

Increasing light intensity increases the rate of
photosynthesis...but a plant will reach a
maximum rate.