Energy and Metabolism Chapter 8 - PowerPoint PPT Presentation

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Energy and Metabolism Chapter 8

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Title: Energy and Metabolism Chapter 8


1
Energy and MetabolismChapter 8
2
Energy

3
Energy
4
Energy
5
Metabolism
  • All chemical reactions carried out by the cell

6
Metabolism
  • Catabolic reactions
  • Break down large molecules into smaller
    substances
  • Releases energy or is exergonic

7
Metabolism
  • Anabolic reactions
  • Synthesis of large molecules from smaller
    substances
  • Requires energy or is endergonic

8
Metabolism
  • Biochemical pathways
  • Reactions in a cell that occur in sequence
  • Product of one reaction becomes substrate in
    next reaction
  • Pathways are highly regulated coordinated
  • Feedback inhibition
  • End product of a reaction inhibits the pathway
    from producing more.

9
Energy
10
Energy
  • Bioenergetics
  • Analysis of how energy powers activities of
    living systems
  • Growth, order, reproduction, responsiveness
    regulation
  • Require energy to happen

11
Energy
  • Energy
  • Capacity to do work
  • Kinetic energy
  • Energy of motion
  • Potential energy
  • Energy of position or stored energy

12
Energy
  • Kinetic energy
  • Potential energy

13
Energy
  • Most of the work done by living organisms is the
    transformation of potential energy to kinetic
    energy
  • Thermodynamics¬†
  • Study of energy heat changes

14
Energy
  • Sun main source of energy
  • Energy from sun is used to combine smaller
    molecules to make larger molecules
  • Energy is then stored in the chemical bond

15
Energy
  • Redox(oxidation-reduction) reactions
  • Transfer of an electron or electrons
  • Play a key role in flow of energy in biological
    systems
  • An electron is passed from one atom to another
    energy is passed

16
Law of thermodynamics
  • Laws of thermodynamics govern all energy changes
    in the universe.
  • ¬†First law of thermodynamics
  • Energy cannot be created or destroyed
  • It can change from one form to another.
    (potential to kinetic)
  • Total amount of energy stays the same

17
First law
  • In living organisms
  • Eating transfers energy from bonds in food to
    organism
  • Potential energy is transferred to kinetic energy

18
First Law
  • Heat random motion of molecules
  • Heat can be lost during conversions
  • Sun replaces energy that is lost as heat

19
Second law
  • Second law of thermodynamics
  • Transformation of PE to heat (random motion of
    molecules).
  • Entropy (disorder) in universe is increasing

20
Second law
  • Energy transformations tend to proceed
    spontaneously
  • Convert matter from a more ordered state to a
    less ordered
  • More stable state.

21
Second law
  • Entropy(s) Disorder in a system
  • Enthalpy (H) heat content
  • Free energy(G) Amount of energy available to do
    work in any system.
  • Amount of energy available to break then make
    other chemical bonds

22
Second law
  • GGibbs free energy
  • ?G ??H - T?S (TKelvin temp)
  • ?G is positive than products have more energy
    than reactants
  • Due to more energy in bonds or less randomness
  • Endergonic reaction

23
Endergonic reaction
24
Second law
  • ?G is negative products have less energy than
    reactants
  • H is lower (bond energy) or
  • S is greater- more randomness
  • Exergonic any reaction that releases energy

25
Exergonic reaction
26
Exergonic reactions
27
Energy
28
ATP
  • ATP powers energy requiring processes in cell
  • 1. Chemical work (making polymers)
  • 2. Transporting substances across the membranes
  • 3. Mechanical work
  • Muscle movement, cilia

29
ATP
  • Structure of ATP
  • Ribose sugar
  • Adenine
  • 3 phosphate attached in a row

30
ATP
31
ATP
32
ATP
  • ATP
  • ADP
  • Losses a inorganic phosphate
  • Hydrolysis
  • 7.3kcal/mole of energy is released.

33
Activation Energy
  • Energy needed to initiate a reaction
  • Exergonic endergonic reactions both require
    activation energy.
  • Reactions with higher AE tend to move forward
    more slowly

34
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35
Enzymes
  • Catalyst in living organisms
  • Large three-dimensional globular protein

36
Enzymes
  • Substrate Molecule that is going to undergo the
    reaction
  • Active sites Specific spots on enzyme that
    substrates bind to.
  • Enzyme-substrate complex enzymes are bound to
    substrates with a precise fit.
  • Induced fit when the substrate causes the enzyme
    to adjust to make a better fit
  • ES ES E P

37
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38
Enzymes
  • Only small amounts are necessary
  • Can be recycled
  • Specific
  • Speeds up reactions
  • Different types of cells have different enzymes
  • Determine course of chemical reactions in the cell

39
Enzyme examples
  • Lipase, protease
  • Carbonic anhydrase
  • CO2 H2O H2CO3
  • Lactate dehydrogenase
  • Lactate to pyruvate
  • Pyruvate dehydrogenase
  • Enzyme that starts the Kreb cycle

40
Enzymes
  • Most enzymes are proteins
  • RNA has been shown to catalyze some reactions
  • Ribozymes
  • RNA catalysts are specific speed up reactions

41
Enzymes
  • Factors that affect rate of enzyme-catalyzed
    reactions
  • 1. Concentration of the enzyme substrate
  • 2. Factors that affect the 3-D shape of the
    enzyme
  • Temperature, pH, salt concentration regulatory
    molecules

42
Enzymes
  • Inhibitor
  • Binds enzyme prevents it from working
  • Occurs at end of a pathway to stop reactions
  • Two types of inhibitors
  • Competitive
  • Noncompetitive

43
Enzymes
  • Allosteric site
  • On/off switch for enzyme
  • Allosteric site usually at a different location
    than active site
  • Allosteric inhibitor
  • Binds at allosteric site stops enzyme activity
  • Activitors
  • Bind increases activity

44
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45
Enzymes
  • Cofactor
  • Assists enzyme function (Zn, Mg, Cu)
  • Coenzymes
  • Cofactors that are not proteins but are organic
    molecules
  • Help transfer electrons energy associated with
    electrons
  • Vitamins are coenzymes
  • NAD is an important coenzyme
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