lecture 2: energy and metabolism Flashcards
what is metabolism?
sum of all the chemical reactions within an organism
what catalyzes reactions in our body?
enzymes
what is a catabolic reaction?
-breaks down complex molecules into simpler compounds
-releases energy
what type of reaction is cellular respiration?
catabolic
what is an anabolic reaction?
-builds complex molecules from simpler ones
-requires energy
what type of reaction is photosynthesis?
anabolic
what are metabolic pathways?
they are series of reactions where the product of one reaction is the reactant of the next one. these pathways exist in our body. an enzyme catalyzes each reaction.
what is the first law of thermodynamics?
energy is neither created or destroyed, it is transformed.
what is the second law of thermodynamics?
every energy transformation makes the universe more disordered (increases entropy).
what is the cause of the second law of thermodynamics?
during every reaction, some usable energy is lost as heat.
true or false, all energy transformations are 100% efficient.
false! always some energy lost as heat
what is Gibb’s free energy? what is the formula?
portion of a system’s energy that is available for work. G=H-TS
what shows you if a chemical reaction is spontaneous or not?
-if delta G is negative: spontaneous, energy is released
-if delta G if positive: not spontaneous, energy us consumed
what is the formula for the change in free energy (2)
-delta G= G final state-G starting state
-delta G= delta H- T(Delta S)
what is the difference between endergonic and exergonic?
-endergonic: requires an input of energy
-exergonic: net release of energy
give an example of a spontaneous (exergonic) reaction
cellular respiration
give an example of a non-spontaneous (endergonic) reaction
photosynthesis
what is a trick to know if a reaction is spontaneous/non-spontaneous, depending on a free energy graph?
if the energy level of the products is greater than the reactants, its non-spontaneous
when can a system not do ANY work?
when its at equilibrium, because Delta G=0
if a human cell is at equilibrium, can it survive?
no. since no work can be done inside the cell, the cell would die
how are non-spontaneous reactions powered?
through energy coupling
true or false? going against the concentration gradient requires energy
true!
what is energy coupling?
when a spontaneous reaction is physically coupled with a non-spontaneous process so that energy released from the spontaneous reaction is used to power the non-spontaneous one
how is the production of ATP an example of energy coupling?
1) glucose is broken down (spontaneous)
2) protons are (H+) are pumped from one side of the mitochondria to the other, against the concentration gradient (non-spontaneous)
3) the protons return to equilibrium, respecting the concentration gradient (spontaneous)
4) when the proteins return to equilibrium, they pass by a channel that is attached to a turbine. when they pass this turbine, they spin it, which attaches pi to ADP, and thus make ATP (non-spontaneous)
is the work in our body endergonic or exergonic?
endergonic. thats why we need food and water to power cellular work.
what are the 3 types of work done in our body that are endergonic?
-chemical (synthesis), like protein synthesis
-mechanical (beating cilia, chromosome movement, actin-myosin muscle contraction)
-intracellular transport (active transport)
is the hydrolysis (breakdown) of ATP exergonic or endergonic?
it is highly exergonic. the energy released is how we power cellular work
what is inorganic phosphate (pi)?
H3PO4
where does the main source of energy come from when ATP IS hydrolisized? what does the part broken off become?
the last phosphate group. the broken off phosphate group becomes an inorganic phosphate
How is the ATP cycle renewable?
how much ATP can be formed from one glucose molecule?
in theory 94, in reality, 32 (energy lost as heat)
how can ATP activate a reactant? give an example.
it can couple its hydrolysis to an endergonic chemical reaction. it can transfer one of its PHOSPHATE groups to the reactant. an example of this is the conversion of glutamic acid glutamine. We can link the hydrolysis of ATP to an endergonic reaction
true or false? a reaction coupled to ATP hydrolysis is spontaneous.
true!
what type of work can we couple ATP to in order to power them?
chemical (Synthesis) and transport work (active transport)
how does ATP couple in order to power transport work?
the addition of a phosphate group (negative charge) to a carrier protein disrupts bonds on the protein, which makes it change forms. this change of shape allows it to move a molecule across a membrane. when P comes off, its now Pi, and the carrier protein changes shapes again.
