Ch 9 + 10 Flashcards
What is the point of cellular respiration?
to make ATP
aerobic respiration
consumes oxygen with organic fuel to harvest chemical energy
anaerobic respiration
uses substances other than oxygen to harvest chemical energy (all same until end of ETC)
Redox reactions
oxidation-reduction reactions
electron transfers from one reactant to another, which releases energy
oxidation
loss of electron
reduction
addition of electron
reducing agent
electron donor
oxidizing agent
electron acceptor
Cellular respiration equation
C6H12O6 + 6O2 –> 6CO2 + 6H2O + ATP
Which substance is oxidized and which is reduced in respiration?
glucose is oxidized, oxygen is reduced
What particle really represents the energy content of respiration?
electrons
Electrons are ______ from _______
stripped from glucose
Calculate energy efficiency
Glucose: -686 kilocalories/mole
ATP: -7.3 kilocalories/mole
Mr. Beer: net 36, 38% efficient
Book: net 32, 34% efficient
3 stages of respiration and where they occur
- Glycolysis: cytosol
- Pyruvate Oxidation and Krebs Cycle: matrix of mitochondria
- Oxidative phosphorylation: inner membrane of mitochondria
Function of NADH and FADH
carry electrons like a wheelbarrow
Glycolysis stages
energy investment and energy payoff
Glycolysis: beginning and end, ATP, NADH and FADH
glucose to 2 pyruvates
net 2 ATP (2 used, 4 formed)
net 2 NADH
Pyruvate oxidation and Krebs Cycle: beginning, middle, and end, ATP, NADH and FADH
pyruvate to acetyl CoA to CO2
1 ATP per turn (2 total before ox phos)
3 NADH, 1 FADH
Oxidative phosphorylation stages
electron transport chain and chemiosmosis
Oxidative phosphorylation: beginning and end, ATP
NADH and FADH2 to H20 and ATP
26-28 ATP
Which two chemical mechanisms are responsible for generating ATP?
substrate-level phosphorylation and oxidative phosphorylation
substrate-level phosphorylation
enzyme transfers phosphate group from substrate to ADP
Oxidative phosphorylation
energy released by redox reactions of ETC powers ATP synthesis
Cytochromes
electron carriers in ETC made up of protein and heme group. Breaks free energy drop into manageable steps, increasing electronegativity.
chemiosmosis
energy coupling mechanism: energy stored in hydrogen ion gradient across a membrane is used to drive cellular work like ATP synthesis
ATP synthase
enzyme, molecular rotary motor, uses existing ion gradient to power ATP synthesis
Oxidative phosphorylation: big picture
ETC uses exergonic flow of electrons from NADH and FADH2 to pump hydrogen ions into intermembrane space and then they diffuse down gradient through the synthase to power synthesis
proton motive force
the hydrogen ion gradient used to synthesize ADP and Pi
fermentation
continuous generation of ATP by substrate-level phosphorylation of glycolysis
conditions for fermentation
oxygen is not present
must have sufficient supply of NAD+
alcohol fermentation
pyruvate to acetaldehyde, reduced to ethanol, and CO2
ex: yeast
lactic acid fermentation
pyruvate reduced to lactate
ex: muscle cells during strenuous exercise
control of respiration
step 3 of glycolysis: phosphofructokinase
feedback inhibition by ATP and citrate
stimulation by AMP
photosynthesis
conversion of light energy to chemical energy that is stored in organic molecules
Photosynthesis is a/an __________ process.
anabolic
What are the two processes of photosynthesis
light (dependent) reactions and the Calvin Cycle (dark/ light independent reactions)
light reactions beginning and end
solar energy to chemical energy and production of ATP and NADPH
Calvin Cycle beginning and end
chemical energy to organic molecule G3P to make others like glucose
Which substance is reduced and which is oxidized in photosynthesis?
CO2 is reduced and H20 is oxidized
What makes photosynthesis different from respiration in terms of electrons?
electrons are given by H20 rather than C6H12O6 and carried by NADPH rather than NADH
why does chlorophyll appear green?
only reflects green light, absorbs and uses rest
What does light do to electrons? What substance provides these electrons in ps?
split H20 is the source
light drives transfer of electrons to acceptor NADP+ for reduction
What prevents excited electrons from falling back to ground state?
continuous absorption of photons (provide energy required to move to excited state
What part of the z-scheme is similar to respiration?
electron transport chains
How does cyclic electron flow occur?
uses only photosystem 1
electrons cycle back to cytochrome complex
generates ATP
no production of NADPH or oxygen
What enzyme in the Calvin Cycle acquires carbon (CO2)?
RUBP carboxylase/ rubisco
(initial) products of Calvin Cycle
G3P: 3-phosphoglycerate
Three phases of dark reactions
- carbon fixation
- reduction (G3P)
- regeneration of CO2 acceptor (RUBP)
fixation
combine with another substance to make usable
Other than G3P, the Calvin Cycle also produces:
ADP and NADP+ + Pi
wasteful and slow process
photorespiration: fixation of oxygen
does not produce sugar or ATP
C4 plant pathway
O2 rich mesophyll cells export four-carbon compound to O2 poor bundle-sheath cells for Calvin Cycle
CAM plants
light reactions in day, dark reactions esp with carbon at night
