Download Photosynthesis

Bell Ringer (1 of 2)
1. Identify each form of transport as passive or
active:
•
•
•
•
•
•
Pinocytosis
Facilitated Diffusion
Exocytosis
Osmosis
Simple Diffusion
Phagocytosis
Bell Ringer (2 of 2)
2. Identify each form of transport as passive or
active:
• A protein is used to move glucose across the cell
membrane, from high to low concentrations.
• Water diffuses across the cell membrane.
• The cell membrane changes shape to allow waste
products to leave.
• Sodium ions use an ion channel to enter the cell.
• A protein is used to move glucose across the cell
membrane, from low to high concentrations.
Photosynthesis
How do plants harvest sunlight to create
food?
Photosynthesis
• Photosynthesis is the process of using water
(H2O) and carbon dioxide (CO2) to create glucose
(C6H12O6) and oxygen (O2).
• As you recall, the chloroplasts are cellular
organelles required for photosynthesis.
• Photosynthesis is important for several reasons:
• It creates glucose, or food for the cell
• It provides oxygen gas to other organisims
• It removes carbon dioxide from the atmosphere
Photosynthesis
• Photosynthesis was discovered by a number of
different scientists:
• Jan van Helmont discovered that water was a key
reactant in photosynthesis.
• Joseph Priestley discovered that oxygen was
produced during photosynthesis.
• Jan Ingenhousz discovered that light was required
for photosynthesis.
Photosynthesis
• Since photosynthesis requires light, the final
formula is:
light
• H2O +CO2 → C6H12O6 + O2
• The energy needed to reach the activation level
is provided by light. Afterwards, the glucose
produced will be used up for energy or stored as
starch (complex carbohydrate).
Photosynthesis
• Since photosynthesis requires light, the final
formula is:
light
• H2O +CO2 → C6H12O6 + O2
• The energy needed to reach the activation level
is provided by light. Afterwards, the glucose
produced will be used up for energy or stored as
starch (complex carbohydrate).
Photosynthesis
• Chloroplasts can conduct photosynthesis
because they possess chlorophyll, a pigment
that can absorb certain wavelengths of light.
• Sunlight is composed of several wavelengths of
energy, some of which are visible. There are
seven visible colors: red, orange, yellow, green,
blue, indigo and violet (ROY G BIV).
• There are two types of chlorophyll, which absorb
both the blue-violet and red parts of the visible
spectrum. Green, yellow and orange remain.
Exit Ticket
1. Write the COMPLETE reaction for
photosynthesis.
2. What pigment is primarily found within the
chloroplasts?
3. These pigments absorb red and blue-violet
light, and reflect _____________________.
Photosynthesis
• Within the chloroplasts are thylakoids, which are
stacks of sacs filled with chlorophyll and other
pigments.
• The thylakoids are the light collection units inside
the chloroplasts.
Photosynthesis
• A stack of thylakoids is called a granum. Each
stack is connected to one another.
• Photosynthesis is divided into two different sets
of reactions. The light reactions take place inside
the thylakoids.
Photosynthesis
• The extra space inside the chloroplasts BUT
outside the thylakoids is called the stroma.
• Photosynthesis is divided into two different sets
of reactions. The dark reactions take place within
the stroma.
Photosynthesis
• The light reactions
are needed to
produce ATP and
NADPH, which will be
used to make sugars.
• As you know, ATP is
used to provide
energy around the
cell as needed.
Photosynthesis
• ATP contains three
phosphate groups.
• The bonds that hold
them together all
contain energy, but
only the third
phosphate matters.
• Breaking this bond
provides us with
energy, and converts
ATP to ADP.
Photosynthesis
Photosynthesis
• NADP+ is an electron carrier – a molecule that
transports high-energy electrons where they are
needed.
• It can carry two electrons, turning NADP+ into
NADPH.
Photosynthesis
Photosynthesis
• In the light reactions:
• Energy from light is used to break the bonds in
TWO molecules of water (2 H2O). This provides us
with four electrons, four hydrogen ions (H+), and
two atoms of oxygen (2 O).
• The electrons are energized and bound to NADP+.
Since each NADP+ can carry two electrons, we get
two NADPH.
• The hydrogen ion are pumped out, forming three
ATP in the process.
• The oxygen becomes oxygen gas (O2).
Photosynthesis
• While this seems complicated, all you have to
remember is that the light reactions use water
and light to supply us with ATP, NADPH and
oxygen gas.
• The net reaction is:
light
• 2 H2O + 2 NADP+ + 3 ADP +3 Pi →
2NADPH + 3 ATP + O2
Exit Ticket
1. The light reactions take place in ____________.
2. The light reactions produce _____ for energy,
and _____ for carrying electrons.
3. Write the formula for light reactions.
Photosynthesis
• The dark reactions are needed to store all the
energy produced in the light reactions. ATP and
NADPH are not stable, so they need to be used
to make glucose rather quickly.
• For these reactions, carbon dioxide will be used
up to produce precursors for biomolecules.
These reactions are called the Calvin cycle.
Photosynthesis
• In the dark reactions:
• Six molecules of carbon dioxide (6 CO2) are
combined with six molecules of 5 carbon atoms.
All together there will be 12 3-carbon molecules
and 12 oxygen atoms.
• The energy from 12 ATP and 12 NADPH is used up
to provide hydrogen, and to bond all of the atoms
together.
• Of the 12 3-carbon molecules, two are removed
(along with the oxygen and hydrogen) to make
biomolecules.
Photosynthesis
• Dark reactions, continued:
• We are left with 10 3-carbon molecules. These are
converted back to 6 5-carbon molecules. In the
process, 6 ATP are formed.
• These 5-carbon molecules will be combined with
six new molecules of carbon dioxide (6CO2) to
begin the cycle again.
Photosynthesis
• Again, this seems complicated. What you need
to remember is that CO2, ATP, NADPH and
carbon molecules are used up to supply
biomolecules, including glucose.
• The net reaction is:
• 6 CO2 + 12 NADPH + 12 ATP + 30 C
→ [6C + 12H + 6O] + 12 NADP+ +
6ATP + 6 ADP 30 C
Exit Ticket