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Bioenergetic

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Biosynthesis is the formation of new bonds. Create new molecules for ... is related to changes in enthalpy and entropy H = G T S where T is temperature in K ... – PowerPoint PPT presentation

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Title: Bioenergetic


1
Chapter 5
  • Bioenergetic

2
Energy
  • Capacity to do work
  • Ability to cause specific changes
  • 6 categories of change
  • Synthetic
  • Mechanical
  • Concentration
  • Electrical
  • Generation of heat
  • Generation of light

3
Types of Change
4
Synthetic Work
  • Biosynthesis is the formation of new bonds
  • Create new molecules for growing cell
  • Also must maintain structures in the cell
  • Energy needed to make energy rich organic
    molecules from subunits active subunits

5
Mechanical Work
  • Physical change in position or orientation of
    cell flagella or cilium to move organisms
  • Muscle contraction
  • Separate chromosomes
  • Cytoplasmic streaming
  • Ribosomes moving on mRNA

6
Concentration Work
  • Move molecules or ions against a gradient
  • Increase the concentration in cell or remove
    cellular waste
  • Maintaining Na/K concentration in the cell

7
Electrical Work
  • Specialized concentration work
  • Ions transported across membrane, establishes an
    electrical potential across the membrane
  • ATP generation in cellular respiration
  • Photosynthesis
  • Nerve impulses
  • Uses 2/3 of the total energy in an organism

8
Heat
  • Major use of energy in animals that regulate
    their body temperature
  • Takes about 2/3 of total energy
  • Create heat when the ion transport is happening

9
Bioluminescence
  • Light production
  • Specialized kind of energy

10
Sunshine Ultimate Energy Source
  • Energy comes from the sun or organic food
    molecules
  • 2 types of organisms
  • Phototrophs capture light by photosynthetic
    pigments
  • Store energy as organic molecule
  • Can also act as chemotrophs
  • Chemotrophs energy is stored in chemical bonds
  • Fermentation partial breakdown of organic
    molecules
  • Cellular respiration electrons move from
    chemical bonds to O2
  • Aerobic is when O2 is final electron acceptor
  • Anaerobic is when no O2 is present

11
Flow of Energy in Biosphere
12
Bioenergentic
  • Applied thermodynamics energy flow
  • Heat, other forms of energy, conversions from 1
    form to another
  • System part of a universe we want to study
  • Open system shares energy with surroundings
  • Closed system cannot take in energy or release
    energy to the surroundings
  • Surrounding everything else

13
Energy Exchange
  • Between system and surroundings
  • As heat hotter to colder, not useful to cells
  • As work drive any process other than heat flow
  • Energy changes expressed in calories amount of
    energy required to warm 1 gram of water 1 degree
    C at 1 atmosphere pressure

14
1st Law of Thermodynamics
  • Law of conservation of energy
  • Amount of energy is constant in the universe
    although the form of the energy may change
  • Never created or destroyed

15
Internal Energy (E)
  • Energy stored in a system
  • ?E E2 E1 where 2 is after process or products
    and 1 is before process or reactants
  • Change in heat content or enethalpy (H)
  • ?H estimated to be ?E
  • ?H Hproducts Hreactants
  • -?H is exothermic, reactants release heat
  • ?H is endothermic, heat taken up by reactants

16
Exothermic and Endothermic
17
2nd Law of Themodynamics
  • Thermodynamic spontaneity whether a reaction or
    process can go but says nothing about whether it
    will go
  • In every physical or chemical change, the
    universe always tends to greater disorder or
    randomness or entropy or free energy (S)
  • ?S change in randomness

18
Free Energy (G)
  • Measure of spontaneity for a system
  • ?G is related to changes in enthalpy and entropy
  • ?H ?G T ?S where T is temperature in K
  • Exothermic - ?H is negative and increase in
    entropy (?S) - ?G is negative
  • Endothermic - ?H is and increase in entropy
    (?S) - ?G can be negative or positive

19
?G
20
Spontaneous Reactions
  • Decrease in ?G, ?G is lt 0 and is negative
  • Exergonic energy yielding in terms of ?G
  • Endogonic energy requiring, increase in ?G
  • Tells only that a reaction can go, potential to go

21
Understanding ?G
  • Equilibrium constant (Keq) is the ration of
    products to reactants at equilibrium
  • A ? B Keq Beq/Aeq with B being product
    and A being reactants
  • If concentration ratio is lt Keq then not enough
    of B and reaction will tend to go to the right to
    generate more B
  • If concentration ratio is gt Keq then B is too
    high and the reaction will move to the left to
    make more A

22
Free Energy vs Equilibrium
  • Free energy is lowest at equilibrium
  • The tendency for equilibrium is the driving force
    for every chemical reaction

23
Standard Free Energy
  • Standard state - 25C temperature, 1 atmosphere
    pressure, reactants and products at mol/L and at
    standard H
  • ?G - standard free energy
  • standard conditions
  • pH 7
  • ?G (?G at pH 7) is more useful
  • If negative thermodynamically spontaneous
  • If positive cannot occur in the direction
    written
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