Notes

biologists want to know which reactions occur spontaneously and which require input of energy

to do so, they need to determine the energy and entropy changes that occur in chemical reactions
free energy - energy to do work - when temp and pressure are uniform
change in entropy - change in enthalpy in Kelvin - systems instability
change in energy is negative for all spontaneous processes - processes with zero or positive g are never spontaneous
spontaneous processes can be harnessed to perform work
equilibrium, is the state of maximum ability

exergonic free energy and spontaneous and endorgonic absorbs energy and not spons
reactions in a closed systems ( no outside energy to enter) will reach equilibrium
cells are never in equil - open systems
metabolism if never at equil state
catabolic pathway in a cell release free energy
kinds of work
chemical work
transport work
mechanical work
energy coupling involved ATP - energy shuttle
energy is released from ATP - forming ADP and energy
the energy from exergonic reaction drives every endergonic reactions - coupled reactions are exergonic phosphorylation transfer phosphate group to other molecule - phosphorylated intermediate

ATP hydrolysis leads to a change in protein shape and function (whenever bonds are broken)
ATP is renewable resource that is regenerated. constantly being used and remade. through catabolic and anabolic pathways

at normal temp - catalyst is a chemical agent that speeds up a reaction without being consumed by the reaction
an enzyme is a catalytic protein ex. sucrase is an enzymes that speeds up the hydrolysis of sucrose

initial energy to kickstart a chemical reaction (thermal energy absorbed by the environment) - activation energy
catalysis - enzymes speeds up specific reactions by lowering the activation energy
do not effect the change in free energy
reactant that an enzyme acts on is called the substrate
binds to substrate forming a enzyme substrate complex
fit that gets adapted when the substrate comes in - both change (induced fit)
how?
orienting substrates correctly
straining substrate bonds

affecting rate
increasing substrate concentration all active sites will be engaged
more enzymes

effected by
heat and ph
chemicals that specifically influence the enzyme

enzymes have an optimal temp and ph
optimal conditions favor the most active shape for the enzyme molecule
co facrots are non protein enzyme helpers
may be inorganic
competitive inhibitors bind to the active site of an ezyme competing with the substrate(blocking the active site)
non" " bind to another part of the enzyme causing the enzyme to change shape and making the active site less effective
ex. toxins, poisions, pesticides, etc.
mutations lead to changes in amino acid composition
altered amino acids result in novel enzyme activity or altered substrate specifity
if beneficial - natural selection - spread to future generations

allosteric regulation - may either inhibit or stimulate an enzyme's activity

cooperativity - form of ^ that amplify enzyme activity
one substrate primes an enzyme to act more readily
^ b/c it affects catalysis
feedback inhibition - the end product of a metabolic pathway shuts down the pathway
- prevents a cell from wasting chemical resources

that ones that can't be made from something else - essential enzymes

alter active site - alter reaction/function

structures within cell help bring order to metabolic pathways

enzymes act as structural components in a cell

chapter 9

living cells require energy
work = assembling polymers
ecosystem - energy enters as sunlight and leaves as heat
photosynthesis = O2 and organic molecules used in cellular respiration
cells use chemical energy stored in organic molecules to generate ATP, powers work
catabolic pathways release stored energy by breaking down complex molecules
electron transfer plays a major role in these pathways
central to cellular respiration
fermentation partial degradation of sugars that occurs with 02
aerobic respiration consumed organic molecules and 02 = ATP
ana" " is similar but consumed compounds other than 02

cellular res - includes both ana" & aero - helpful to trace cellular res with the sugar glucose
transfer of elections released energy stored in organic - redox reaction
oxidation - substance loses election
reduction - gains election(pos charge is reduced)
electron donor - reducing agent
receptor - oxidizing agent
**study redox

NADH - passes the electrons to the electron transport chain
- passes electrons in a series of steps instead of one big movement
moves to O2 in a energy yielding tumble - more it jumps down, more energy it yields
harvesting energy in three steps
glycolysis breaks down glucose into two molecules of pyruvate
citric acid cycle (completes breakdown of glucose)
oxidative phosphorylation (accounts for most of the ATP synthesis)

glycolysis two stages
energy investment
energy pay off - doesn't need oxygen

need to know what to start with, what to end with - where it occurs