begins with a specific molecule, which is then altered in a servies of defined steps, resulting in a certain product. Each step of the pathway is catalyzed by a specific enzyme.
A molecule →Enzyme 1 = Reaction 1 → B Molecule → Enzyme 2 = Reaction 2 → C Molecule → Enzyme 3 = Reaction 3 → D Product
Catabolic pathways
breakdown pathways
anabolic pathways
consume energy to build complicated molecules from simpler one
bioenergetics
the study of how evnery flows throught living organisms
catabolic and anabolic pathways
break down complexes and realease energy and build compounds to store energy when in excess....downhill and uphill avenues of the matabolic map
Energy
capacity to cause change
some forms of energy can be used to move matter against forces (gravity, friction)
energy exists in various forms and the work of life depends on the ability of cells to transform energy form one form to another
Kinetic Energy
energy of motion - can be transfered from one object to another - pool player
Thermal energy
kinetic energy associates with the random movement of atoms or molecules
potential energy
energy that matter possesses because of its location or structure
chemical energy
potentioal energy available for release in a chemical reaction
thermodynamics
study of energy transformations that occur in a collection of matter
1) system - matter under study
2) surroundings - everything outside the system
3) isolated systems - unable to exchange energy with its surroundings (liquid in a bottle)
4) open system - able to exchange energy with its surroundings
first law of thermodynamics
the energy of the universe is constant
Energy can be transferred and transformed byt it caoont be created or destroyed (also know as the principle of censervation of energy)
entropy
measure of disorder or randomness
second law of thermodynamics
every energy transfer or transformation increases the entropy (disorder) of the universe
any process that occurs on its own with out input of energy, will increase the entropy of the universe - water flowing downhill, a car rusting, animal giving off heat and CO2
spontaneous
a process that can occur without an input of energy
for a process to occur spontaneously it must increase the entropy of the universe
nonspontaneous
prosess that cannot occur without the input of energy
Exergonic reaction
"energy outward"
net release of free energy because the chemical mixture loses free energy
exergonic reactions are those that occur spontaneously
endergonic reaction
"energy inward"
absorbs free energy from its surroundings
stores free energy in its molecules - nonspontaneous
Metabolism and Equilibrium
systems at equilibrium have no free energy - not capable of doing work - dead
a living cell is not a equilibrium - constant flow of materials in and out of the cell keeps the metabolic pathwas from ever reaching equilibrium - cell continues to work throughout its life
Cell does three kinds of work
chemical work - pushing of endergonic reactions - nonspontanious - uphill - making polymers from monomers
Transport work - pumping substances across cell membranes against direction of spontaneous movement
Mechanical work - contraction of muscle cells, movement of chromosomes during cellular respiration
energy coupling
the use of an exergonic process to drive an endergonic one
ATP mediates most energy couplings and acts as the immediate source of energy that powers cellular work
ATP
adenosine triphosphate
contains:
ribose (5C) sugar with the nitrogenous base adenine
chain of three phosphate groups bonded to it
Hydrolysis of ATP
Reactants =ATP + 1 molecule of water
Products = ADP + free phosphate + energy
energy release comes from the chemical change to a state of lower free energy
phosphorylated
when ATP is hydrated and a phosphate group comes off and it added to some other molecule - the recipient of the phosphate group is phosphorylated
How ATP performs work
a cells proteins harness energy released by ATP hydrolysis to perform the three types of cellular work - chemical, transport, and mechanical
Fermentation
partial degradation of sugars without the use of oxygen
(catabolic process)
aerobic respiration
anaerobic repsiration
oxygen is consumed as a reactant along with organic fuel
without oxygen - some prokaryotes harvest chemical energy without any oxygen
cellular respiration
includes both aerobic and anaerobic processes but usually refers to the aerobic process