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An introduction to metabolism (ch 8)/cellular respiration &…
An introduction to metabolism (ch 8)/cellular respiration & fermentation (ch 9)
The free-energy change of a reaction tells us whether or not the reaction occurs spontaneously (8.2)
spontaneous energy/non-spontaneous
spontaneous energy: A reaction that occur without energy input; they can happen quickly or slowly
ΔG is negative for all spontaneous processes, as no energy would be required
Reactions don’t normally happen spontaneously because some reactions need energy and have less entropy than others
processes with zero or positive ΔG are never spontaneous, as energy would be required
entropy
Entropy is a measure of molecular disorder, or randomness
free energy
energy that can do work when temperature and pressure are uniform, as in a living cell
Gibs free energy equation
ΔG = ΔH – TΔS
ΔH: the change in enthalpy (change in total energy)
ΔS: change in entropy
ΔG: change in free energy
T: temperature in Kelvin units
enthalpy
the system's internal energy plus the product of its pressure and volume
ATP powers cellular work by coupling exergonic reactions to endergonic reactions (8.3)
ATP is composed of ribose (a sugar), adenine (a nitrogenous base), and three phosphate groups
When ATP is hydrolyzed, Energy is released from ATP when the terminal phosphate bond is broken. This release of energy comes from the chemical change to a state of lower free energy, not from the phosphate bonds themselves.
Through energy coupling, the exergonic process of ATP hydrolysis drives endergonic reactions by transfer of a phosphate group to specific reactants, forming a phosphorylated intermediate
ATP becomes ADP after it is hydrolyzed, it becomes “recharged” through the addition of a phosphate to ADP
mechanical
transport
chemical
ATP facilitates these activities as the exergonic process of ATP hydrolysis is used to drive an endergonic process
An organism's metabolism transforms matter & energy, subject to the laws of thermodynamics
Anabolic
Anabolic means consuming energy to build complex molecules from simpler ones
the synthesis of glucose
sugars joining together to form glycogen
the synthesis of protein from amino acids
fatty acids forming a triglyceride
A + B = AB
Catabolic
Catabolic means releasing energy by breaking down complex molecules into simpler compounds.
the breakdown of glucose
in the presence of oxygen
Cellular respiration
AB = A + B
metabolism
Metabolism is the totality of an organism’s chemical reactions. Metabolism is an emergent property of life that arises from orderly interactions between molecules
energy
the capacity to cause change; some forms of energy do work by moving matter
potential energy
the energy that matter possess based as a result of its location or structure (stored energy).
chemical energy
kinetic energy
energy associated with the relative motion of objects (energy in motion)
thermal energy
heat (thermal energy in transfer from one body of matter to another)
temperature (a measure of the average kinetic energy of the molecules in a body of matter)
laws of thermodynamics
According to the first law of thermodynamics, the energy of the universe is constant, energy can be transferred and transformed, but it cannot be created or destroyed.
According to the second law of thermodynamics, every energy transfer or transformation increases the entropy of the universe; entropy is a measure of molecular disorder, or randomness. Stating as energy changes from one form to another, disorder in a closed system increases.
Enzymes speed up metabolic reactions by lowering energy barriers (8.4)
An Enzyme is a protein that is often called a catalyst
Enzyme-substrate complex: when the enzyme binds to its substrate
Substrate: The reactant that an enzyme acts on
Active site: refers to the specific region of an enzyme where a substrate binds and catalysis takes place
Enzymes can only affect very specific reactions through the use of an active site & induced fitting ( the tightening of the binding between a substrate and an enzyme)
Two major environmental factors can hinder an enzyme’s ability to function
temperature
pH level
Regulation of enzyme activity helps control metabolism (8.5)
Enzymes are regulated in an organism through, In feedback inhibition
the end product of a metabolic pathway shuts down the pathway, as feedback inhibition prevents a cell from wasting chemical resources by synthesizing more product than is needed.
competitive inhibitor
binds to the active site
Enzymes are regulated in an organism through allosteric regulation
Cooperativity is a form of allosteric regulation that can amplify enzyme activity as, One substrate molecule primes an enzyme to act on additional substrate molecules more readily
occurs when a regulatory molecule binds to a protein at one site and affects the protein’s function at another site.
noncompetitive inhibitator
does not bind to the active site
intermediate step (9.2)
reactants
2 Pyruvate
products
2 Acetyl CoA
2 CO2
2 NADH
between glycolysis and Krebs cycle
Acetyl coA formed by the removal of -CO2 & H+ from pyruvic acid
glycolysis (9.1
)
Reactants
2 ATP
1 Glucose
products
2 Pyruvate
4 ATP
2 NADH
Glycolysis is a sequence of ten enzyme-catalyzed reactions
transforms glucose into pyruvate acid
citric acid cycle (9.3)
reactants
2 Acetyl CoA
products
2 ATP
6 NADH
2 FADH2
4 CO2
releases stored energy through the oxidation of acetyl-CoA derived from carbohydrates, fats, and proteins, into adenosine triphosphate and carbon dioxide
Oxidative Phosphorylation and Electron Transport Chain
(9.4)
reactants
10 NADH
2 FADH2
product
Up to 34 ATP
In the electron transport chain, electrons are passed from one molecule to another, and energy released in these electron transfers is used to form an electrochemical gradient.