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
anerobic
occurring without the use of molecular oxygen
Which pathway creates the most NADH Glycolysis Pyruvate oxidation Citric Acid Cycle Electron transport
Citric acid cycle
Portion of pathway that consumes ATP Glycolysis Pyruvate oxidation Citric acid cycle Electron transport
Glycolysis
How are polysaccharides broken down to provide energy
First hydrolyzed to glucose. Glucose then passes through glycolysis, pyruvate oxidation, and the respiratory chain where its energy is captured in ATP
How are lipids broken down to provide energy
lipids are broken down into glycerol and fatty acids. Glycerol is converted to dihydroxyacetone phosphate, an intermediate of glycolysis. Fatty acids are highly reduced molecules that are converted to acetyl CoA in a process called Beta oxidation.
How are proteins broken down to provide energy
Hydrolyzed to their amino acid building blocks. 20 different amino acids feed into glycolysis or the citric acid cycle at different points
wavelength
The distance between successive peaks of a wave train, such as electromagnetic radiation
source of oxygen produced by photosynthesis comes from
H2O
three processes of the calvin cycle
Fixation of CO2, Reduction of 3PG to form glyceraldehyde 3-phosphate, regeneration of the CO2 acceptor.
Calvin Cycle: Fixation of CO2
Initial reaction adds the one-carbon CO2 to an acceptor molecule. Immediate product in a 6 carbon molecule, which quickly breaks down into 2 three-carbon molecules.
Rubisco
plants need a lot of this to perform enough photosynthesis to satisfy the needs of growth and metabolism. Is probably the most abundant protein in the world
Calvin cycle: Reduction of 3PG to form glyceraldehyde 3 phosphate
Series of reactions involves a phosphorylation and reduction. The product is G3P which is a three carbon sugar phosphate, also called trios phosphate
Calvin Cycle: Regeneration of the CO2 acceptor
Most of the G3P ends up as ribulose monophosphate, and ATP is used to convert this compound into RuBP so for every “turn” of the Calvin Cycle, one CO2 is fixed and the CO2 acceptor is regenerated.
The calvin cycle
Uses ATP and NADPH generated in the light reactions to produce G3P from CO2. The G3P is used as a starting material for the production of glucose and other carbohydrates. Six turns of the cycle are needed to produce one molecule of the hexose glucose
which statement about ATP is true?
The synthesis of ATP is an energy-neutral reaction.
The hydrolysis of ATP to ADP and Pi is an exergonic reaction.
The phosphate bond energy of ATP is used to power catabolic metabolism.
ATP is a building block of protein.
The phosphate bond energy of ATP may be transformed into the energy in a magnetic field.
The hydrolysis of ATP to ADP and Pi is an exergonic reaction
Reagents, such as dinitrophenol, increase the permeability of the mitochondrial inner membrane to protons. The addition of dinitrophenol to a suspension of animal cells should, over the short term
inhibit mitochondrial ATP synthesis
The mitochondrial ATP synthase
makes ATP at the expense of the proton gradient established by electron transport.
The mitochondrial electron transport chain
oxidizes the intermediate electron carriers, NADH and FADH2.
Glycolysis
is an oxidation–reduction process.
The end products of glycolysis are
pyruvate, ATP, and NADH.
In the complete oxidation of glucose, 6 CO2 molecules are formed per glucose molecule oxidized. From the list below, choose the correct numbers of CO2 molecules released by glycolysis (Gly), the citric acid cycle (CAC), and pyruvate oxidation (Pyr).
Gly 0; CAC 4; Pyr 2
Which statement about the citric acid cycle is true?
It requires NAD+ and FAD
Fermentation
results in the formation of lactic acid or ethanol.
The ultimate source of energy for ATP synthesis in chloroplasts is
light
What is a photosystem
A photosystem is a complex of pigments, proteins, and reaction center chlorophyll.
The immediate source of energy for ATP synthesis in chloroplasts is
the electrochemical proton gradient
During photosynthesis in green plants, water is
oxidized to O2 in the light.
In photosynthesis, NADPH is used for the
reduction of 3-phosphoglycerate (3PG).
The major product of photosynthesis that is exported from the leaves to the rest of the plant is
sucrose
