Cellular Energetics

Catabolic pathways Fermentation: Partial degradation (O 2 ) Cellular respiration: Full degradation (O 2 ) Organic compounds + O 2  CO 2 + H 2 O + energy (gasoline burning) C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 O + energy

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

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

C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 O + energy C 6 H 12 O 6 is oxidized/reduced while O 2 is oxidized/reduced C 6 H 12 O 6 is the _____agent while O 2 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 O 2 in your body?

Enzyme facilitate the break down of organic fuels to CO 2 in a SERIES of steps. Why not just one step? Electrons (along with a proton) are stripped from glucose, but not directly to O 2, instead they are transferred to…

NAD Conezyme derived from the vitamin niacin NAD ox vs NAD re Very little PE lost Energy can be tapped into when ATP needs to be made

How do electrons finally reach oxygen?

Substrate level phosphorylation 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” Location? Inputs? Outputs? Purpose?

Fermentation

Lab 5: Cellular Respiration

Description  using respirometer to measure rate of O 2 production by pea seeds non-germinating peas germinating peas effect of temperature control for changes in pressure & temperature in room

Lab 5: Cellular Respiration Concepts  respiration  experimental design control vs. experimental function of KOH function of vial with only glass beads

Lab 5: Cellular Respiration Conclusions   temp =  respiration   germination =  respiration calculate rate?

Sources of energy Autotrophs (self-feed from CO2 and inorganic materials): plants, some algae, some bacteria Synonym: Producers Photosynthesis (photoautotroph) 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 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

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?

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)

6CO 2 + 6H 2 O light > C 6 H 12 O 6 + 6O 2 Where does the O2 come from? Hypothesis 1: CO2 + C  C + O2 C + H2O  CH2O Hypothesis 2 (van Niels)  Studies bacteria that DIDN’t produce O2  CO2 + 2H2S  CH2O + H2O + 2S  CO2 + 2H2O  CH2O + H2O + O2  Confirmed with radioactive tracers to track its fate Visible globules

REDOX chemistry 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 NADP+ : Same function as NAD+ Photophosphorylation

How do photosystems work? Only photons with energy equal to the atoms ground state  excited stated is absorbed Redox Why does isolated chlorophyll fluoresce?

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 Purpose: _____ Location: ____ Input : ____ Output : ____

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 + DPIP ox = blue DPIP red = clear  measure light transmittance  paper chromatography to separate plant pigments

Lab 4: Photosynthesis Concepts  photosynthesis  Photosystem 1 NADPH  chlorophylls & other plant pigments chlorophyll a chlorophyll b xanthophylls carotenoids  experimental design control vs. experimental

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)