cellular metabolism Flashcards
metabolic pathways
series of steps to alter molecules
anabolic pathways
build molecules, requires energy
catabolic pathways
break down molecules, releases energy
energy is the ability to
create change
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energy of movement
thermal energy
energy of heat due to random molecule movement
electrical energy
energy of charged particles
chemical energy
energy stored in covalent bonds
1st rule of thermodynamics
energy cannot be created or destroyed
2nd law of thermodynamics: energy transformation…
energy transformation increases entropy (disorder)
processes that decrease entropy require
require energy
biological systems are highly ordered which means
they require a lot of energy to maintain, and lose a lot of energy as heat
Gibbs free energy measures
energy of chemical reaction
Gibbs free energy
energy available to do work
+ Gibbs free energy
reaction requires energy and universe becomes more organized
negative gibs free energy
reaction releases energy and universe becomes less organized
why is negative Gibbs free energy more stable than positive?
*More stable because disorder in the universe is always trending towards randomness and disorder
*Since they change less, they have less ability to do work (they just want to sit there since they are so stable)
exergonic reaction: change in free energy is …
G < 0
in exergonic reactions:
reactants have ____ energy than products?
reactions ____ energy?
reaction is ______?
Reactants have more energy than products
Releases energy
Reaction is spontaneous
in endergonic reactions: change in free energy is
G > 0
in endergonic reactions:
reactants have ____ energy than products?
reactions ____ energy?
reaction is ______?
less; require; non spontaneous
what happens if cells reach equilibrium?
they will die
three main categories of work that cells do:
chemical reactions, transporting things, and mechanical.
chemical work (by cells)
powering endergonic reactions
transport work (by cells)
pumping substances up concentration gradients
mechanical work (by cell)
move the cell or nearby structures
to do work, cells use
adenosine triphosphate (ATP)
ATP is composed of
Nucleotide (adenine) attached to 3 phosphates
energy currency of cells
ATP
smallest unit of energy in the cell
ATP
- ATP hydrolysis
-phosphates can be removed via hydrolysis
*Releases energy and creates ADP (adenosine diphosphate)
- phosphorylation
phosphate released from ATP hydrolysis is transferred to another molecule, creating a phosphorylated intermediate
Couples exergonic ATP hydrolysis with endergonic reaction
phosphorylation
Coupled reactions are still exergonic if
ATP releases more energy than endergonic reaction uses
- regenerating ATP
Phosphate can be added to ADP via dehydration to recreate ATP
regenerating ATP requires
energy
primary purpose of cellular respiration
to create ATP
activation energy
energy needed (IN) to start reaction
____reactions require energy to start
exergonic
catalysts function
decrease activation energy