Intro to metabolism Flashcards
What is photosynthesis
Plants capture energy from the sun and store it in the chemical bonds of sugars and other food molecules
Cellular Respiration
Organisms release energy stored in the chemical bonds of food molecules they eat (or the sugar they produce in photosynthesis) and use it as fuel
What is potential energy
energy that matter possesses because of its location or structure
what is kinetic energy
energy associated with random movement of atoms or molecules
what is chemical energy
potential energy available for release in a chemical reaction
What is the general definition of metabolism
it is the totality of an organisms chemical reactions
what is a metabolic pathway
it begins with a specific molecule and ends with a product. Each step is catalyzed by a specific enzyme
What are Catabolic pathways?
they release energy by breaking down complex molecules into simpler ones
(cellular respiration)
Exergonic process
What are anabolic pathways?
They consume energy to build complex molecules from simpler ones
(photosynthesis)
Endergonic
What is the general definition of energy?
the capacity to do work or cause change
What is a system and the surroundings?
the system is the matter under study and the surroundings is everything outside of that
What is the first law of thermodynamics
energy can be converted and transformed but cannot be created or destroyed
what is the second law of thermodynamics?
Every energy transfer increases the entropy of the universe
What occurs in a spontaneous process of energy transformation?
the more orderly forms are less stable and are converted into a less ordered and more stable form
What is free energy
it is a measure of a systems instability and its tendency to flow into a more stable state
When can a spontaneous process occur?
When it is moving toward equilibrium
When does free energy decrease?
during a spontaneous process
What does it mean when G is positive
products have more free energy than reactants
it is non spontaneous
it is endergonic
What does it mean when G is negative
Products have less free energy
it is spontaneous
it is exergonic
whats the difference between endergonic and exergonic
endergonic reactions require energy
exergonic reactions release energy
How does ATP release energy?
When the terminal phosphate groups break by hydrolysis
this produces a lower free energy state since the phosphate groups repel eachother and have higher potential energy
how does ATP power cellular work?
by coupling exergonic (spontaneous) reactions to power endergonic (non-spontaneous) reactions
what are the three types of work a cell does?
chemical (synthesis of polymers)
transport (pumping of substances across a membrane against its concentration gradient
Mechanical: movement of chromosomes during mitosis, cilia and flagella, contraction of muscles
ATP hydrolysis drives
endergonic reactions
How does ATP drive transport
it phosphorylates transport proteins, causing them to change shape that allows transport of solutes
how does ATP drive mechanical work?
it binds noncovalently to motor proteins and then is hydrolyzed, causing a shape change that walks the motor protein forward
How does atp drive chemical work
energy coupling using ATP hydrolysis
How is ATP regenerated
it is regenerated by the addition of a phosphate group to ADP
energy is required for this process and is supplied through catabolic (exergonic) reactions in the cell
what is a catalyst
it is a chemical agent that speeds up a reaction without being consumed by it
what does the shape of the enzyme do
it stabilizes a temporary association between substrates
what is activitation energy
it is energy needed to start a chemical reaction
energy must be absorbed before energy is released to form products
how is the rate of a reaction affected by activation energy?
if the activation energy is larger, the reaction proceeds more slowly
what do enzymes do to activation energy?
they lower it
what are substrates
the reactant that the enzyme acts on
what is the active site of an enzyme
a pocket for substrate binding
what is induced fit
it occurs when a substrate brings chemical groups of the active site into positions that enhance their ability to catalyze the reaction
what are cofactors
they are nonprotein enzyme helpers
they may be inorganic (metal in ionic form)
or organic
what are coenzymes
organic cofactors (vitamins)
what are competitive inhibitors
they bind to the active site of an enzyme, competing with the substrate
what are noncompetitive inhibitors
they bind to another part of an enzyme and cause it to change shape, making the active site less effective
what is allosteric regulation
it occurs when a regulatory molecule binds to a enzyme at one site and affects the proteins function at another site
what is the affect of allosteric regulation on enzymes
it may inhibit or stimulate an enzymes activity
What is feedback inhibition
it occurs when the end product of a metabolic pathway shuts down the pathway
it prevents the cell from wasting chemical resources
