Title: Cell Energy
1Cell Energy
2Energy
- The ability to do work or cause change! Involves
movement! (Even at the molecular level!) - Kinetic E (KE) The E that is actually doing
work, i.e. moving something and transferring that
motion! - Heat, light, sound
- Potential E (PE) Stored E, the capacity to
perform work due to location or position
3Types of Cell Work
- Chemical endergonic reactions that would not
occur spontaneously - Ex. Synthesis of polymers from monomer
- Mechanical physical motion
- cilia beating, muscle contraction, flow of
cytoplasm - Transport active transport
- Moving molecules against the concentration
gradient
4Thermodynamics
- The study of the behavior of energy flow in
natural systems.
5Laws of Thermodynamics
- First Law aka. The Law of Conservation of
Energy Energy is neither created nor destroyed,
energy can be transformed. - The energy in the universe is constant.
- Second Law energy conversions reduce the order
of the universe (increasing entropy) - Heat
- As a particular system becomes more ordered, its
surroundings become more disordered - A cell is an island of low entropy in an
increasingly random universe! - FYI Third Law if all the kinetic energy could
be removed, a state called absolute zero would
occur. Absolute zero results in a temperature of
0 Kelvin or -273.15 Celsius.
6The First Law The Transformation of Energy
Conservation of energy means it can change forms
between kinetic and potential, but it never
disappears.The total amount of energy is always
the same.
7Transferring Energy in Food
- Food is digested and stored in our bodies as
potential energy. - This potential energy can be transformed into
kinetic energy as our bodies move and exercise. - Chemicals may also be considered from a potential
energy (PE) or kinetic energy (KE) standpoint.
One pound of sugar has a certain PE. If that
pound of sugar is burned the E is released all at
once. The E released is KE (heat). So much is
released that organisms would burn up if all the
E was released at once. Organisms must release
the E a little bit at a time.
When you exercise, you get hot. What do you think
is happening?
8A reminder
- Heat cannot be transferred from a colder to a
hotter body. As a result of this fact of
thermodynamics, natural processes that involve
energy transfer must have one direction, and all
natural processes are irreversible.
9The Second Law of Thermodynamics
- Second Law energy conversions reduce the order
of the universe. - The amount of disorder in a system is called
entropy. (energy lost as heat.) - As a system becomes more ordered, its
surroundings become more disordered! - Lots of disorder high entropy
- Order low entropy
10Moving towards equilibrium
- The ultimate result of the Second Law of
Thermodynamics is that energy in the universe is
steadily deteriorating, or "un-winding", to lower
and lower quality. The universe is steadily
moving toward total equilibrium
11In summary
- In simplest terms, the Laws of Thermodynamics
dictate the specifics for the movement of heat
and work. - Basically, the First Law of Thermodynamics is a
statement of the conservation of energy - the Second Law is a statement about the direction
of that conservation - and the Third Law is a statement about reaching
Absolute Zero (0 K).
12Thermodynamics is the study of the inter-relation
between heat, work and internal energy of a
system.
- The British scientist and author C.P. Snow had an
excellent way of remembering the three laws - You cannot win (you cannot get something for
nothing, because matter and energy are conserved) - You cannot break even (you cannot return to the
same energy state, because there is always an
increase in disorder entropy always increases). - You cannot get out of the game (because absolute
zero is unattainable).
13Reminder
- Energy associated with reactions
14Exergonic Reactions
- Chemical reactions which involve a net release of
free E. - Ex. Cellular respiration - the chemical reaction
in which sugars are broken down to CO2 and H2O,
releasing E. - Requires an initial input of E to get the
reaction started, called activation E.
15Endergonic Reactions
- Reactions that involve a net absorption of free
energy. - Ex. photosynthesis - the chemical reaction in
which CO2 and H2O are combined to make sugars,
storing E E. - Requires an initial input of E to get the
reaction started, called activation E.
16Metabolism
- The sum total of all the endergonic and exergonic
reactions that take place in a working cell and
organism.
17Energy Coupling
- Using energy released from exergonic reactions to
drive essential endergonic reactions. - ATP molecules are the essential to energy
coupling in biological systems. - ATP powers nearly all forms of cellular work.
18Enzymes!
- Go back and visit your information on enzymes!
- http//www.indiana.edu/oso/animations/An6.html
19Cell Energy
- ATP Adenosine triphosphate
20ATP Notice the bonds
21ATP Cycle
22Phosphorylation
- ATP, the "high-energy" exchange medium in the
cell, is synthesized in the mitochondrion by
addition of a third phosphate group in a process
referred to as phosphorylation. - ATP is synthesized at the expense of solar energy
by photophosphorylation in the chloroplasts in
the of plant cells.
23(No Transcript)
24ATP moves energy around by phosphorylation.
- Phosphorylation is the addition of a phosphate
(PO4) group to a protein molecule or a small
molecule. - Think hot potato!
25ATP
26How it works
- ATP works by losing the endmost phosphate group
by hydrolysis when instructed to do so by an
enzyme. - This reaction releases a lot of energy, which the
organism can then use to build proteins, contact
muscles, etc. - The reaction product is adenosine diphosphate
(ADP), and the phosphate group - Even more energy can be extracted by removing a
second phosphate group to produce adenosine
monophosphate (AMP).
27Cont
- When the organism is resting and energy is not
immediately needed, the reverse reaction takes
place and the phosphate group is reattached to
the molecule using energy obtained from food or
sunlight. - Thus the ATP molecule acts as a chemical
'battery', storing energy when it is not needed,
but able to release it instantly when the
organism requires it. -
28ATP Cycle
- Remember, phosphorylation transfers energy.
- What is ATP synthase (a.k.a. ATP ase)? What does
it do?
29What is this energy used for?
30How much energy do we use? Biosynthesis in E.
coli modified from Ensign(1998)
Cell constituent Number of molecules per cell Molecules synthesized per second Molecules of ATP required per second for synthesis
DNA 1 0.00083 60,000
RNA 15,000 12.5 75,000
Polysacchar ides 39,000 32.5 65,000
Lipids 15,000,000 12,500.0 87,000
Proteins 1,700,000 1,400.0 2,120,000