Name: ________________________
Biology-Harlacher
Chapter 9-Energy in a Cell Notes
In this Chapter we will discuss two main concepts:
__________________-when autotrophs/producers make sugar using sunlight.
___________________________-when any organism turns a sugar into energy
ATP
In our cells, we need energy in order to carry out vital cell processes (and live).
Most of our energy is in the form of a molecule called Adenosine TriPhosphate (_______).
ATP has a related molecule called Adenosine DiPhosphate (______). ADP can store energy
by adding a phosphate group which makes ATP.
When ATP loses a phosphate group, this __________________. It works like a battery that
can be recharged.
ATP is only used for ____________________________________, so only a small amount is
found in cells. To store energy long term, cells use the basic sugar glucose (_________).
The glucose can then be broken down as needed and used to _____________ ADP into ATP.
Photosynthesis
Photosynthesis is the process of changing __________________ into storable and
__________________ for a cell. ATP is a good storage molecule for the day, but what about
longer periods without light (like night)?
Photosynthesis turns light energy into ___________, which can then be turned into
_________ for longer-term energy storage.
Photosynthesis uses carbon dioxide and water to turn light from the sun into glucose and
oxygen gas.
The formula for photosynthesis is:
Pigments and Light
How do plants do this? They use a ___________ called __________________ which exists in
chloroplasts.
Sunlight looks white to us, but is actually a _____ of all the different colors (visible and
invisible to us).
Plants gather the sun’s energy with light absorbing molecules called pigments (which are
_____________).
The three types of pigments in plants are _________________________________________
Chlorophylls are the major pigment in plants, but _________________________green well.
What happens if a color of light is not absorbed? It is _____________.
This is why most plants appear _________ to us.
This is also why we see different colored leaves in the _________…the chlorophyll is no
longer produced and we see the other pigments that still remain (for a time).
There are two main types of Chlorophyll:
__________________
__________________
When plants absorb light, much of the energy is transferred directly to _________, which
allows photosynthesis to work.
Inside a Chloroplast
Chloroplasts, you should remember, only exist inside __________________ and the cells of
other producers.
Inside the chloroplast are sac-like membranes called __________________. They are
arranged in stacks called _________. (Granum for one.)
Proteins in the thylakoids arrange the pigments into clusters known as ________________.
These are what collect light inside of a chloroplast.
There are two parts to Photosynthesis:
The ____________________________________ which take place within the thylakoids.
The __________________ (or Dark Reactions or Light-Independent Reactions) which takes
place in the stroma. The stroma is the space inside the chloroplast that is not taken up by
thylakoids.
Energy Transfer:
When the electrons within chlorophyll are _________, they gain a lot of _________.
Think of it as a hot charcoal briquette from a fire. If you wanted to move it, you wouldn’t
pick it up with your hands, you would use a carrier. Cells treat them the same way.
Cells use __________________ to transport them. The process is called electron transport
(duh) and the carriers are known as ____________________________________.
Some of the notable carriers:
_______ holds two electrons and a Hydrogen ion (H+). This changes it into _______.
_________ holds two electrons and an H+ ion. This changes into _________.
_________ holds two electrons and two H+ ions. This changes into _________.
These carriers can then be used to carry electrons throughout the cell to be used where
needed.
The Light-Dependent Reactions (or the Light Reactions)
These reactions __________________. This is why plants need light.
The light reactions produce oxygen gas and turn ADP and NADP+ into ATP and NADPH
respectively. It happens in ___________________________:
First, pigments in __________________ absorbs light. This excites the electrons and raises
their energy levels. These electrons are then passed on to the electron transport chain.
New electrons are gained from __________________. Enzymes inside of the thylakoid
break each H2O into 2 electrons, 2 H+ ions, and 1 oxygen atom.
The two electrons replace the electrons lost by chlorophyll to the electron transport chain.
Oxygen is __________________ and released into the air. This is the source of almost all of
our oxygen on earth.
The _________ hydrogen ions from water are released within the thylakoid.
Second, the excited electrons move through the electron transport chain to _______________
Energy from the electrons is used to transport H+ ions from the _________ to inside the
_________________.
Third, pigments in Photosystem I use energy from light to ___________________________.
NADP+ picks them and H+ up and becomes NADPH.
Fourth, as electrons are ________ from chlorophyll to NADP+ more H+ ions are pumped across
the thylakoid membrane. The inside of the thylakoid fills up with __________________H+ ions.
This makes the outside membrane negatively charged. The difference between the inside
and outside in charge provides the energy to make _________.
Fifth (and last), H+ ions can’t just cross the membrane. However, they can pass through a
protein called ATP synthase which is a __________________.
As the H+ ions pass through ATP synthase the protein is turned like a ______________ and
it binds ADP and a phosphate group together to make ATP.
This means that the light reactions produce H+ ions and ATP.
But what do we do with all this _________ and _________?
The Dark Reactions
The __________________ are more commonly called the __________________.
They occur in the _________ of the chloroplast.
ATP and NADPH can hold energy, but are ___________________________ to hold onto that
energy for more than a __________________.
During the Calvin Cycle, plants (and other producers) use the ATP and NADPH to build highenergy compounds that can stored for a long time. It does this with __________________
_________ such as glucose.
It happens in 4 parts:
First, ____ carbon molecules enter the cycle from the atmosphere (courtesy of ______). These
each combine with a 5-carbon molecule called RuBP (six total). The result is 12 molecules of
___________________________.
Second, our twelve 3-carbon molecules are converted into higher energy forms. This energy
comes from _______ and _________ made in the light reactions.
This leaves us with _________ and _________ to return to the thylakoids and be used
again. The end product is called _________.
Third, two of the twelve 3-carbon molecules are removed from the cycle.
The cell uses these to make sugars, lipids, amino acids, and other compounds that are
needed for _____________________________________________.
Fourth, the remaining ten 3-carbon molecules are ___________________________ into six 5carbon molecules (_________).
They _________ the cycle again.
The Calvin Cycle needs __________________ of CO2 to produce one glucose (_________).
The plant then uses glucose to make _________ (storage), _____________ (structure), and
just to break down for energy in cellular respiration.
When other organisms eat plants, they get the energy from these __________________.
Rates of Photosynthesis
Amount of _________ available.
_______________ (the essential enzymes must be between 0°C and 35°C (32-95 degrees F).
The intensity of _________.
Because of this different producers are adapted to different conditions! Think of a cactus, vs.
an oak tree vs. a pine tree.