Chapter 6 - Pathways that Harvest and Store Chemical Energy Flashcards
redox reaction
a reaction in which one substance transfers one or more electrons to another substance (aka reduction-oxidation reaction)
Reduction
the gain of one or more electrons by an atom, ion, or molecule.
Oxidation
the loss of one or more electrons
T/F oxidation and reduction always occur together
true
T/F
The more reduced a molecule is, the more energy is stored in its covalent bonds
true
cellular respiration
set of metabolic reactions used by cells to harvest energy from food.
Glycolysis
a 6 carbon monosaccharide glucose is converted into two three carbon molecules of pyruvate.
happens in cytoplasm
involves 10 steps, steps 1 and 3 use ATP
2 NADH made in step 6
steps 7, 10 make ATP
0 FADH2 made
Pyruvate Oxidation (transition)
two three carbon molecules of pyruvate are oxidized into two-carbon molecules of acetyl CoA and two molecules of CO2 happens in mitochondria 0 ATP 1 NADH per pyruvate (x2) 0 FADH2 made
Citric Acid Cycle
two, two-carbon molecules of acetyl CoA are oxidized to four molecules of CO2
happens in mitochondria
8 steps
operates twice for each glucose molecule that enters glycolysis
3 NADH (x2) = 6
1 FADH2 (x2) = 2
1 ATP (x2) = 2
final products of glycolysis
two molecules of pyruvate, two molecules of ATP, and two molecules of NADH
oxidative phosphorylation
ATP formation in the mitochondrion, associated with flow of electrons through the respiratory chain.
electron transport
the passage of electrons through a series of proteins with a release of energy which may be captured in a concentration gradient or in chemical form such as NADH or ATP H+ gradient must be present Hydrogen ions power ATP synthase about 32 ATP 0 NADH 0 FADH2
key role of O2 in cells
is to act as an electron acceptor and become reduced
ATP synthase
This enzyme uses the H+ gradient to drive the synthesis of ATP via a mechanism called chemiosmosis.
make ATP at rates of up to 100 molecules per second
Chemiosmosis
the movement of ions (normally H+) across a semipermeable barrier from a region of higher concentration to a region of lower concentration.
in eukaryokes occurs in the mitochondria and the chloroplasts
How does the quantity of ATP produced as a result of activity by the electron transport chain compare to the quantity produced as a result of glycolysis?
The quantity of ATP produced as a result of electron transport in much more than that produced as a result of glycolysis
why is oxygen important in the electron transport pathway and ATP synthesis?
Oxygen accepts electrons at the end of the electron transport chain to free the pathway for a new set of electrons
cyanide binds to and inhibits the enzyme cytochrome oxidase. How does this property of cyanide explain its effect as a lethal poison ?
It shuts down movement of electrons along the electron transport chain
Chemical energy stored in glucose –> Chemical energy stored in NADH and FADH2 –> ______________ Chemical energy stored in ATP
Chemical energy stored in a proton concentration gradient