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Making and Using Energy
in Cells
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Energy in Cells
All cells need energy. Cells get their energy
from small molecules called ATP. ATP is a
“battery” that plugs into molecules and
provides energy for reactions. ATP is made
in mitochondria and goes where it is needed
in the cell.
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ATP is:
1. A cell part
2. A small battery used by cells to do work
3. Is a process used to make energy
No, try again!
Right!
ATP is like a battery that the cell uses
when it needs energy.
ATP is made in:
1. The chloroplast
2. The nucleus
3. The mitochondria
Try again!
Right!
The mitochondria is the powerplant of the
cell because it is where ATP energy is made.
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ATP stands for Adenosine triphosphate.
Each ATP is made of one adenosine with
three phosphate molecules attached. A lot
of energy is required to hold the
phosphates together
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When cells need energy, enzymes remove a
phosphate, releasing the energy stored in
that bond. This released energy can be used
to do work in the cell.
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ATP
ADP
Removing a phosphate from ATP creates one
molecule of ADP (adenosine diphosphate).
ATP has three phosphates
ADP has two phosphates
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Which of the pictures below shows a
molecule of ATP?
Try Again
Right!
ATP is made from one adenosine and three
phosphate molecules.
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Which of the pictures below shows a
molecule of ADP?
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Right!
ADP has adenosine and two phosphates.
Where is the energy stored in ATP?
1. In the adenosine molecule
2. In the phosphate molecules
3. In the bonds between phosphates
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Right!
The energy is in the bond between
phosphates, since so much energy is
required to hold them together.
How does the cell get energy from ATP?
1. It adds another phosphate
2. It removes a phosphate
3. It breaks down Adenosine
Try again
Right!
When the cell needs a battery to run a
process, it clips one phosphate from an
ATP molecule, and then captures and uses
the energy released.
How is ATP made?
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How is ATP Made?
The cell has three ways to make ATP batteries:
• Glycolysis (anaerobic)
• Cellular Respiration (aerobic respiration)
• Fermentation (anaerobic respiration)
The word aerobic means that oxygen is needed.
Anaerobic means that oxygen is not needed.
What do you think the cell needs in order to make
ATP through cellular respiration?
1. Oxygen
2. Carbon Dioxide
Do what? Try again!
Right!
Aerobic respiration is where the cell makes
ATP in the presence of oxygen. Anaerobic
respiration is where the cell can make ATP
when no oxygen is available.
To understand how ATP is made, we have
to better understand sugar (glucose)
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Glucose
Sugar molecules contain rings of carbon. As in ATP,
energy is required to hold carbon molecules
together. Because glucose has six carbon–carbon
bonds, it has loads of stored energy.
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In glucose, the energy is stored:
1. In the bonds between carbon
molecules
2. In the carbon molecules themselves
3. In the aerobic rings
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Right!
Glucose has six carbons, and the bonds
between carbons store energy. When the
bonds are broken, energy is released.
How can glucose be used to make ATP?
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Glycolysis
The first way of making ATP from bond
energy is called glycolysis. Glycolysis is
anaerobic, meaning that no oxygen is
needed for the process to work.
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Which is correct?
1. Anaerobic means that oxygen is
needed, and aerobic means
“without oxygen”
2. Aerobic means that no oxygen is
required, and aerobic is
something that uses oxygen
Try again!
Right!
Think about doing aerobics. Anyone doing
aerobics really needs oxygen – that is
why they are breathing so hard.
Glycolysis is:
1. Aerobic
2. Anaerobic
Try again!
Right!
Glycolysis is anaerobic – no oxygen is
needed to make ATP from glucose
How does glycolysis work?
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Glycolysis
• In glycolysis, a six-carbon glucose is split into two
molecules that contain three carbons each
• These 3-carbon molecules are called pyruvic acid
• Splitting glucose in half releases enough energy to make
2 ATP
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Which is correct?
1. In glycolysis, one glucose is broken
into two pyruvic acid molecules
2. In glycolysis, one glucose is broken
into two ATP
3. In glycolysis, one glucose is
converted to a smaller pyruvic acid
molecule
Try again!
Right!
In glycolysis, one 6-carbon glucose molecule
is split to form two 3-carbon pyruvic acids
What happens when glucose is split in half?
1. The energy in glucose increases
2. It gains energy
3. The energy released is used to make 2
ATP
Try again!
Right!
In glycolysis, when glucose is split in half, the
energy released by the breaking of bonds is
used to make 2 ATP molecules.
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What happens after glycolysis?
At the end of glycolysis, the cell has 2 new
ATP batteries, and two molecules of pyruvic
acid.
The pyruvic acid still contains lots of energy
in the three carbon bonds
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Which is correct?
1. Glycolysis converts two glucose
molecules to one pyruvic acid and 2 ATP
2. Glycolysis converts two glucose
molecules to two pyruvic acids and 2
ATP
3. Glycolysis converts one glucose
molecule to two pyruvic acid and 1 ATP
4. Glycolysis converts one glucose to two
pyruvic acid and two ATP
Try again!
Right!
In glycolysis, one glucose molecule (6
carbons) is split in half to create 2 pyruvic acid
molecules (3 carbons each). By breaking
carbon bonds, enough energy is released to
create 2 ATP.
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What happens after glycolysis?
Pyruvic acid still has lots of energy left in it.
How does the cell take advantage of this?
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Following Glycolysis
After glycolysis, two methods are possible for
converting pyruvate into even more ATP:
• If oxygen is available, then Cellular (aerobic
respiration) occurs
• If no oxygen is available, then fermentation
(anaerobic respiration) occurs
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What process follows glycolysis if
oxygen is available in the cell?
1.
2.
3.
4.
Cellular respiration
Anaerobic respiration
Fermentaton
Pyruvate
Try again!
Fermentation and anaerobic respiration are
the same thing – neither requires oxygen
Try again!
Pyruvate is one of the products of glycolysis
(the other is ATP)
Right!
Cellular (aerobic) respiration follows
glycolysis when oxygen is available to the
cell.
Cellular respiration occurs in the
mitochondria and uses glucose (pyruvic
acid) to produce CO2, water, and lots of
ATP (38 ATP to be exact)
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What are the three products of
Cellular Respiration?
1.
2.
3.
4.
38 ATP, O2, and glucose
38 ATP, H2O, and glucose
38 ATP, H2O, and CO2
38 ATP, CO2, and glucose
Try again!
Right!
The products of aerobic respiration are CO2,
H2O, and 38 ATP.
Cellular respiration is very efficient – only
one glucose molecule results in 38 ATP
molecules! This is the formula:
C6H12O6 + O2
CO2 + H2O + 38 ATP
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Which is the correct formula for
Cellular respiration?
1.
2.
3.
4.
CO2 + H2O + ATP
Glucose + O2
Glucose + H2O
Glucose + ATP + O2
Glucose + O2
CO2 + H2O + ATP
CO2 + O2 + ATP
CO2 + pyruvate
Try again!
Right!
The correct formula for cellular respiration is:
Glucose + O2
CO2 + H2O + 38 ATP
So, if aerobic respiration is so efficient, why
doesn’t the cell use it all the time?
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Although cell respiration is the best way to
create ATP, it requires the presence of
oxygen. Sometimes oxygen is not
available.
What process must be used to create ATP
when oxygen is not available following
glycolysis?
1. Fermentation
2. Aerobic respiration
3. Cellular respiration
Try again!
Aerobic respiration and cellular respiration
are the same thing, and both require
oxygen.
Right!
The cell must follow glycolysis with
fermentation when no oxygen is available,
or when oxygen is in short supply.
Another name for fermentation is anaerobic
respiration.
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Fermentation
Fermentation makes ATP from glucose
without using oxygen.
Unfortunately, fermentation makes only 2
ATP from each glucose molecule, and
produces a lot of waste material that could
have been converted into more energy.
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The two types of Fermentation
There are two types of fermentation:
• Alcoholic fermentation (used to make
beer, wine, and bread)
• Lactic acid fermentation (used by muscles
in heavy exercise, and used by yeast to
make yogurt and sour cream)
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