Cell Energy - PowerPoint PPT Presentation

1 / 30
About This Presentation
Title:

Cell Energy

Description:

Title: The Cell Membrane Author: Michael Link Last modified by: install Created Date: 9/1/2005 12:31:52 AM Document presentation format: On-screen Show (4:3) – PowerPoint PPT presentation

Number of Views:30
Avg rating:3.0/5.0
Slides: 31
Provided by: Michael2301
Category:

less

Transcript and Presenter's Notes

Title: Cell Energy


1
Cell Energy
  • Lets get moving!

2
Energy
  • 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

3
Types 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

4
Thermodynamics
  • The study of the behavior of energy flow in
    natural systems.

5
Laws 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.

6
The First Law The Transformation of Energy
  • Energy is conserved.

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.
7
Transferring 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?
8
A 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.

9
The 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

10
Moving 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

11
In 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).

12
Thermodynamics 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).

13
Reminder
  • Energy associated with reactions

14
Exergonic 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.

15
Endergonic 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.

16
Metabolism
  • The sum total of all the endergonic and exergonic
    reactions that take place in a working cell and
    organism.

17
Energy 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.

18
Enzymes!
  • Go back and visit your information on enzymes!
  • http//www.indiana.edu/oso/animations/An6.html

19
Cell Energy
  • ATP Adenosine triphosphate

20
ATP Notice the bonds
21
ATP Cycle
22
Phosphorylation
  • 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)
24
ATP 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!

25
ATP
26
How 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).

27
Cont
  • 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.

28
ATP Cycle
  • Remember, phosphorylation transfers energy.
  • What is ATP synthase (a.k.a. ATP ase)? What does
    it do?

29
What is this energy used for?
30
How 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
Write a Comment
User Comments (0)
About PowerShow.com