chapter 8: bioenergetics Flashcards
1st law of thermodynamics
energy is neither created or destroyed
2nd law of thermodynamics
when energy is converted from one form to another, some of that energy becomes unavailable to do work
why can products have less potential energy than reactants?
at least some energy is lost during the reaction; changes forms (heat)
chemical form of energy
stored in bonds
electrical form of energy
separation of charges
heat form of energy
transfer due to temperature difference
light form of energy
electromagnetic radiation stored as photons
mechanical form of energy
energy of motion
metabolism
the sum of all biochemical reactions in an organism
spontaneous, exergonic reactions
when delta G is negative, energy released, energetically favorable
nonspontaneous, endergonic reactions
delta G is positive, energy consumed, need energy input to occur
redox reactions
- may transfer electrons alone or with protons
- reduction: gain of electron
- oxidation: loss of electron
FAD and NAD
- oxidized and reduced constantly - very easy to oxidize and reduce
- need to couple the reduction reaction with another one
- endergonic, nonspontaneous
coupling reactions
exergonic reaction drives an endergonic reaction
ATP
energy currency of the cell
where does ATP hold its energy
phosphate bonds
when is energy released from ATP?
when it is hydrolyzed
- not a redox reaction
- catabolic bc it involves breaking down a molecule
how much ATP does the body turn over every day?
equivalent to its own body weight; ATP continuously recycled in organisms
what is ATP hydrolysis coupled to
endergonic reactions in cells
enzymes
- contain binding sites for coupled reactions so they can occur together
- increase reaction rate exponentially
- max rate depending on concentration
- if all enzyme is bound to substrate - max reaction rate
how do enzymes help biochemical reactions occur
they reduce energy investment into biochemical reactions by facilitating the reaction between molecules
allosteric regulation: noncompetitive inhibition
- binding of regulatory subunit to enzyme, changes shape of enzymes so substrate cant bind at active site anymore
competitive inhibition
molecule similar to substrate binds to active site and blocks substrate binding
allosteric regulation: activation
binding of a regulatory subunit to enzyme, changes shape of enzymes and now substrates can bind to active site
allosteric regulation: adding a phosphate
i could see this being on an exam
changes 3-D shape of a protein to reveal an active site so a substrate can bind
cofactors
nonprotein molecules or inorganic ions, often a metal ion, that some proteins require in order to function - includes coenzymes and ATP
how did metabolic pathways probably evolve?
not sure if we will actually need to know this
backwards
1) enzyme 1 evolves and converts substrate 1 into a key product
2) substrate 1 is used up, new enzymatic activity evolves to produce substrate 1 from another substrate
3) the cycle repeats, additional steps added to series of reactions ultimately forming a full pathway
glycogen
carbohydrate that represents a huge amount of energy; >30 ATP from one molecule
