ch 9 Flashcards
(34 cards)
how is work powered through sunlight
energy flows into ecosystem through sunlight, and photosynthesis uses it to create oxygen and organic molecules. these products are used in cellular respiration to regenerate ATP
How do catabolic pathways yield energy
by oxidizing organic fuels
ex: fermentation and cellular respiration
oxidation reaction
substance loses electrons
reduction reaction
substance gains electrons
what does more or less reduction and oxidation mean for energy
more reduced a molecule is, the more energy it has stored in its bonds
the more oxidized, the less free energy
oxidation reduction in cellular respiration
glucose is oxidized and oxygen is reduced
why is it important that catabolism occurs step by step and not at once
large release of energy occurs
energy cant be harnessed/stored
NAD
electron acceptor
electrons from consumed organic compounds are transferred to NAD+ to create NADH
NADH
represents stored energy
created when NAD+ accepts electrons(2 H from food)
passes electrons to the ETC
3 ATP made from one NADH
forms in Glycolysis and Krebs cycle
FADH2
electron carrier
only phosphorylates
formed in Krebs cycle
2 ATP per molecule
stages of cellular respiration
glycolysis
citric acid/krebs cycle
oxidative phosphorylation and ETC
Glycolysis location and purpose
cytosol
breaks down glucose into pyruvate
splits glucose into 2
doesn’t require oxygen (anaroebic)
Krebs cycle location and purpose
mitochondrial matrix (inside)
produce carbon dioxide from pyruvate and NADH and FADH2
uses oxygen indirectly (oxygen present surrounding) —> aerobic
oxidative phosphorylation and ETClocation and purpose
inner membrane
electrons from NADH and FADH2 passed to oxygen and generates a lot of ATP
oxygen required
Substrate level phosphorylation in cellular resp
occurs in glycolysis and krebs
generate ATP by phosphorylation of ADP with phosphate from substrates
General steps of glycolysis
sugar is split into and formed into 2 pyruvate
2 ATP is used to form ADP in energy investment stages, while 4 ATP is formed in energy payoff stages
2 NAD+ receive electrons to create 2 NADH
NADH move to ETC and 2 pyruvate go to link reaction and krebs
intermediate step
link reaction
pyruvate is converted to acetylene coA
pyruvate enters the mitochondrion from the cytosol through a transport protein, releases a CO2, converts NAD+ into NADH and binds with coenzyme A
Kreb’s cycle general steps
two occurs per glucose (two pyruvate)
one acetyl coenzyme A enters the cycle and releases 2 carbon, creates 3 NADH, 1 ATP, and 1 FADH2 and NADH
total: 4 CO2, 6 NADH, 2 FADH2, 2 ATP
what do NADH and FADH2 do after Krebs cycle
donate electrons to electron transport chain
oxidative phosphorylation
production of ATP using energy derived from redox reactions of ETC
chemiosmosis
moving ions across membrane down electrochemical gradient
couple ETC to ATP synthesis
ETC general steps
- NADH and FADH2 enter chain and donate electrons via H+ and become NAD+ and FAD.
- electrons are carried from one complex to the next until oxygen accepts the electrons and bonds with hydrogen to form water
- at the same time, H+ protons are being pumped across the membrane to the intermembrane space creating an electrochemical gradient
After ETC
-Chemiosmosis
- H+ protons have a conc. gradient making them want to flow out the intermembrane space
- H+ flow powers ATP synthase, a motor protein
- ATP synthase phosphorylates ADP to form ADP
discrepancies in ATP yield
After NADH transfers electrons via H to cross mitochondrial membranes, it can result in either NAD+ or FAD. NAD+ results in 3 ATP and FAD results in 2 ATP
depends on what shuttle transports electrons from NADH in cytosol
