Transcript Cellular Energetics - University of California, Los Angeles

Cellular Energetics
Catabolic pathways
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Fermentation: Partial degradation (O2)
Cellular respiration: Full degradation (O2)
Organic compounds + O2  CO2 + H2O +
energy (gasoline burning)
C6H12O6 + 6O2  6CO2 + 6H2O + energy
Redox reactions
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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
Partial transfer
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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 doesn’t
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…
NAD
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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?
Substrate level
phosphorylation
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Enzymes transfer a
phosphate group
from the substrate to
ADP
In oxidative
phosphorylation
(discussed tomorrow)
inorganic phosphate
is added to ADP
Glycolysis “splitting of sugar”
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Location?
Inputs?
Outputs?
Purpose?
Fermentation
Lab 5: Cellular Respiration
Lab 5: Cellular Respiration
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Description
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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
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Concepts
respiration
 experimental design
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control vs. experimental
 function of KOH
 function of vial with only glass beads
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Lab 5: Cellular Respiration
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Conclusions
temp = respiration
 germination = respiration
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calculate rate?
Sources of energy
Photosynthesis
(photoautotroph)
Autotrophs (self-feed from CO2
and inorganic materials):
plants, some algae, some bacteria
Synonym: Producers
Chemosynthesis (chemoautotroph)
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
Absorbing/reflecting light
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Problem: How do plants utilize
energy from light to produce
carbohydrates?
Properties of light
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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
Pigment structure/function
Pigment structure/function
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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?
Light dependent reactions
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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)
6CO2 + 6H2O light> C6H12O6 + 6O2
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Where does the O2 come from?
Hypothesis 1: CO2 + C  C + O2
C + H2O  CH2O
Hypothesis 2 (van Niels)
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Studies bacteria that DIDN’t produce O2
CO2 + 2H2S  CH2O + H2O + 2S
Visible
globules
CO2 + 2H2O  CH2O + H2O + O2
Confirmed with radioactive tracers to track its
fate
REDOX chemistry
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REDOX! Water is split  electrons and Hydrogen
ions to CO2. Electrons increase in potential energy,
so energy is NEEDED! (endergonic, +ΔG)
CO2 is reduced to sugar
H2O is oxidized
Photosynthesis overview
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NADP+ : Same function as NAD+
Photophosphorylation
How do photosystems work?
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Only photons with energy equal to the
atoms ground state excited stated is
absorbed
Why does isolated chlorophyll
Redox
fluoresce?
Noncylic electron flow
Noncylic electron flow
Noncylic electron flow
Noncylic electron flow
Noncylic electron flow
Noncylic electron flow
Cyclin electron flow
Function: Regenerate ATP lost
through Calvin Cycle (more
ATP consumed than NADPH)
Electron transport chain
Location: _____
Input: ______
Output: ___
Purpose: _____
Chemiosmosis comparison
Calvin Cycle
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Purpose: _____
Location: ____
Input : ____
Output : ____
Lab 4: Photosynthesis
Lab 4: Photosynthesis
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Description
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determine rate of photosynthesis under
different conditions
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use DPIP in place of NADP+
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light vs. dark
boiled vs. unboiled chloroplasts
chloroplasts vs. no chloroplasts
DPIPox = blue
DPIPred = clear
measure light transmittance
paper chromatography to
separate plant pigments
Lab 4: Photosynthesis
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Concepts
photosynthesis
 Photosystem 1
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NADPH
chlorophylls & other
plant pigments
chlorophyll a
 chlorophyll b
 xanthophylls
 carotenoids
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experimental design
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control vs. experimental
Lab 4: Photosynthesis
 Conclusions
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Pigments
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pigments move at different rates based on
solubility in solvent
Photosynthesis
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light & unboiled
chloroplasts
produced
highest rate of
photosynthesis
Which is the control? #2 (DPIP + chloroplasts + light)