Ch. 8 An Introduction to Metabolism Flashcards
big ideas: different types of energy, (exer/ender/free), ATP structure & function, enzymes, and allosteric activation/inhibition
what is a catabolic pathway?
breaking down of complex things into simpler things: hydrolysis, energy releasing, is exergonic
what is an anabolic pathway?
building up: dehydration synthesis, energy is needed = endergonic
what is the 1st law of thermodynamics?
-there is a finite amount of energy in the universe, and it cannot be created or destroyed, only changed forms
what is the 2nd law of thermodynamics?
the entropy of the universe increases with every energy transfer = organisms must absorb energy to stay organized
what is kinetic energy?
energy of motion - such as molecules moving
what is potential energy?
energy of position or state - such as a reaction giving off energy
what is an open system?
a system that allows both heat and matter to leave it
what is a closed system?
a system that allows heat, but not matter, to leave it
what is free energy?
the portion of a system’s energy that can perform work = G
larger G = more work can be done
-unstable systems have more G than stable ones
what can the body do with spontaneous free energy?
- transport - ex - Na/K pump
- mechanical work - ex - muscle movement
- chemical work - ex - building polymers
how does ATP perform work?
when atp undergoes hydrolysis, it releases a LOT of free energy, which is coupled to reactions that are endergonic [need an input of energy]
what are the three components of ATP?
adenosine [nucleic acid] attached to a ribose sugar, with 3 phosphate groups on the end
-the bond in the last 2 phosphate has a LOT of potential energy stored
what are the functions of enzymes in biological systems?
to reduce the amount of energy required for a reaction by lowering the activation energy
what are the characteristics of enzymes? [6]
- they reduce activation energy
- they have ACTIVE SITES which are very specific, only work w/ certain molecules
- the enzyme is unchanged at the end of the reaction
- enzyme reactions are mostly reversible, depends on [S] and [P]
- if there is unlimited substrate, increasing [enzyme] will increase rate of reaction
- if there is a fixed amount of enzyme, increasing [substrate] will increase rate of reaction until all active sites are filled
what is activation energy?
the amount of energy that must be put into a reaction for it to commence
what is free energy change?
the amount of energy released in the conversion of reactants to products
what is a transition state?
the part of a reaction with the highest potential energy
what factors can affect the function of enzymes?
temperature - too high and the enzyme is denatured, too low and the molecules move too slowly for a reaction to occur
pH - extremes on either end lead to loss of shape and function
what are enzyme cofactors?
inorganic molecules that help enzymes - Fe2+, Cu2+, Zn2+
what are coenzymes?
organic molecules that help enzymes, many involved in ATP-making reactions:
Vitamin B3 = niacin = NADH
Riboflavin = FMN and FAD
Pantothenate = Acetyl CoA
what is competitive inhibition of enzymes?
-a molecule binds to the active site and prevents substrate binding
-often the product of a metabolic pathway
what is a non-competitive inhibitor of enzymes?
a molecule that binds to the enzyme at someplace other than the active site
-ex heavy metals
what is allosteric regulation?
when another molecule binds to a site other than the active site - occurs on enzymes with active/inactive forms
what is an allosteric activator?
a molecule that stabilizes the active form of an enzyme
what is an allosteric inhibitor?
a molecule that stabilizes the inactive form of an enzyme
what is feedback inhibition?
when the first enzymes in a metabolic pathway are inhibited by the product of the pathway
-> avoids unnecessary production of the end product
