Cellular Energetics

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Cellular Energetics
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Catabolic pathways

• Fermentation Partial degradation (O2)
• Cellular respiration Full degradation (O2)
• Organic compounds O2 ? CO2 H2O energy
  (gasoline burning)
• C6H12O6 6O2 ? 6CO2 6H2O energy

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Redox reactions

• Explains how energy is yielded by transfer of
  electrons
• Oxidation Loss of electrons
• Reduction Gain of electrons (OILRIG)
• Na Cl ? Na Cl- (complete transfer)
• To pull electrons away from an atom requires
  input of energy

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Partial transfer

• More electronegative ? more energy needed
• When electrons shift from less electronegative to
  more electronegative atom ? Electron loses
  potential energy, which is released as heat

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• C6H12O6 6O2 ? 6CO2 6H2O energy
• C6H12O6 is oxidized/reduced while O2 is
  oxidized/reduced
• C6H12O6 is the _____agent while O2 is the ____
  agent.
• This reaction is considered exergonic/endergonic,
  therefore it is spontaneous/not spontaneous and
  has a /- change in free energy
• Why are many organic molecules great fuels?
• When a spark is applied to gasoline and oxygen it
  burns and releases a LARGE quantity of energy.
  Why doesnt glucose do the same thing in the
  presence of O2 in your body?

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• Enzyme facilitate the break down of organic fuels
  to CO2 in a SERIES of steps. Why not just one
  step?
• Electrons (along with a proton) are stripped from
  glucose, but not directly to O2, instead they are
  transferred to

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NAD

• Conezyme derived from the vitamin niacin
• NADox vs NADre
• Very little PE lost
• Energy can be tapped into when ATP needs to be
  made

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• How do electrons finally reach oxygen?

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Substrate level phosphorylation

• Enzymes transfer a phosphate group from the
  substrate to ADP
• In oxidative phosphorylation (discussed tomorrow)
  inorganic phosphate is added to ADP

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Glycolysis splitting of sugar

• Location?
• Inputs?
• Outputs?
• Purpose?

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Fermentation
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Lab 5 Cellular Respiration
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Lab 5 Cellular Respiration

• Description
• using respirometer to measure rate of O2
  production by pea seeds
• non-germinating peas
• germinating peas
• effect of temperature
• control for changes in pressure temperature in
  room

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Lab 5 Cellular Respiration

• Concepts
• respiration
• experimental design
• control vs. experimental
• function of KOH
• function of vial with only glass beads

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Lab 5 Cellular Respiration

• Conclusions
• ?temp ?respiration
• ?germination ?respiration

calculate rate?
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Sources of energy
Photosynthesis (photoautotroph)
Autotrophs (self-feed from CO2 and inorganic
materials) plants, some algae, some bacteria
Synonym Producers
Chemosynthesis (chemoautotroph)
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Chloroplast structure
Read through birth of complex cells to get
further detail about other plastids and
organelles such as peroxisomes
Water roots?veins?mesophyll cells Sugar
mesophyll cells?veins?rest of plant CO2, O2 ?
stomata
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Absorbing/reflecting light

• Problem How do plants utilize energy from light
  to produce carbohydrates?
• Properties of light
• While traveling, acts as a wave (properties
  depend on this wavelength)
• When interacting with matter (like your clothes)
  acts as a particle
• Photon Discrete packet of light

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Pigment structure/function
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Pigment structure/function

• When chlorophyll absorbs light, energy is
  transferred to electrons.
  

Plant pigments
Chlorophyll a primary pigment Chlorophyll b
broadens range of wavelengths that can be
used Carotenoids Also broadens range, absorbs,
dissipates excessive energy, prevents interaction
w/ O2 EAT YOUR CARROTS, why?
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Light dependent reactions

• Role of chlorophyll Capture energy from light
• Role of an electron carrier transport electrons
  which carry the energy initially from light
  (NADP 2e- H ? NADPH)

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6CO2 6H2O lightgt C6H12O6 6O2

• Where does the O2 come from?
• Hypothesis 1 CO2 C ? C O2 C H2O ?
  CH2O
• Hypothesis 2 (van Niels)
• Studies bacteria that DIDNt produce O2
• CO2 2H2S ? CH2O H2O 2S
• CO2 2H2O ? CH2O H2O O2
• Confirmed with radioactive tracers to track its
  fate

Visible globules
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REDOX chemistry

• REDOX! Water is split ? electrons and Hydrogen
  ions to CO2. Electrons increase in potential
  energy, so energy is NEEDED! (endergonic, ?G)
• CO2 is reduced to sugar
• H2O is oxidized

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Photosynthesis overview

• NADP Same function as NAD
• Photophosphorylation

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How do photosystems work?

• Only photons with energy equal to the atoms
  ground state? excited stated is absorbed

Why does isolated chlorophyll fluoresce?
Redox
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Noncylic electron flow
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Noncylic electron flow
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Noncylic electron flow
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Noncylic electron flow
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Noncylic electron flow
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Noncylic electron flow
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Cyclin electron flow
Function Regenerate ATP lost through Calvin
Cycle (more ATP consumed than NADPH)
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Electron transport chain

• Location _____
• Input ______
• Output ___
• Purpose _____

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Chemiosmosis comparison
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Calvin Cycle

• Purpose _____
• Location ____
• Input ____
• Output ____

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Lab 4 Photosynthesis
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Lab 4 Photosynthesis

• Description
• determine rate of photosynthesis under different
  conditions
• light vs. dark
• boiled vs. unboiled chloroplasts
• chloroplasts vs. no chloroplasts
• use DPIP in place of NADP
• DPIPox blue
• DPIPred clear
• measure light transmittance
• paper chromatography to separate plant pigments

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Lab 4 Photosynthesis

• Concepts
• photosynthesis
• Photosystem 1
• NADPH
• chlorophylls other plant pigments
• chlorophyll a
• chlorophyll b
• xanthophylls
• carotenoids
• experimental design
• control vs. experimental

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Lab 4 Photosynthesis

• Conclusions
• Pigments
• pigments move at different rates based on
  solubility in solvent
• Photosynthesis
• light unboiled chloroplasts produced highest
  rate of photosynthesis

Which is the control?
2 (DPIP chloroplasts light)
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