Exam 2 - Lecture 9 Flashcards
what three kinds of work must cells do?
- chemical work
- transport work
- mechanical work
what is chemical work?
the synthesis of complex molecules
what is transport work?
the take up of nutrients, elimination of wastes, and maintenance of ion balances
what is mechanical work?
cell motility and movement of structures within the cell
metabolism is a _______ of all the chemical reactions in a cell
total
which of the following generates precursors for biosynthesis, catabolism or anabolism?
catabolism
which of the following requires energy, catabolism or anabolism?
anabolism
match the following:
a. catabolism
b. anabolism
- synthesis of large, complex molecules
- breakdown of large molecules into smaller, simpler ones
a2. catabolism: breakdown of large molecules into smaller, simpler ones
b1. anabolism: synthesis of large, complex molecules
what is thermodynamics?
a science the analyzes the energy changes in a collection of matter called a system (example: a cell)
what are the laws of thermodynamics?
- energy can neither be created nor destroyed
- entropy (the universe wants to constantly increase in entropy)
what is entropy?
the amount of disorder/chaos in a system
what is the free energy equation?
deltaG = deltaH - TdeltaS
(G = H - TS)
what is the free energy equation used for?
it is used to indicate if a reaction will proceed spontaneously
true or false: a positive deltaG mean a rxn is spontaneous.
false; a negative deltaG means a rxn is spontaneous
is a negative deltaG indicate an exergonic or endergonic reaction?
exergonic = negative deltaG
when is a reaction at equilibrium?
when the rate of the forward reaction matches that of the reverse reaction
what is the Keq equation?
[C][D]/[A][B]
- concentration of products over reactants
deltaG = -RT*log(Keq)
just know this i guess
what is the energy currency of the cell?
adenosine 5’-triphosphate; ATP
what is done to make endergonic reactions more favorable?
they are coupled with the breakdown of high energy ATP (an exergonic reaction)
what is the deltaG of ATP hydrolysis?
-7.3 kcal/mol
many metabolic processes involve oxidation-reduction reactions, which is the transfer of ___________
electrons
when electrons move from a donor to an acceptor, this can result in energy _________ which can then be used to form ATP
release
the more electrons a molecule has to donate, the more _________ _____ it is
energy rich
an electron donor and acceptor pair are called what?
conjugate redox pair
what is the equilibrium constant for a redox reaction called?
the standard reduction potential (Eo; “E-naught”)
what is Eo a measure of?
the tendency of a donor agent to lose its electrons
a more negative Eo, the better electron ________ it is. the more positive, the better _________ it is
donor; acceptor
does NADH have a positive or negative Eo? what about O2?
- NADH: negative
- O2: positive
- when electrons move from NADH to O2, energy is made available
the first electron carrier in the ETC has the most ___________ Eo (hint: it’s NADH)
negative
the first electron carrier in the ETC is _________ when electrons are moved onto the next carrier
oxidized (OIL RIG)
where does the electron transport chain take place in bacterial and archaeal cells? how about eukaryotic cells?
- plasma membranes
- mitochondrial (or chloroplast) membranes
what does NAD(P) stand for?
nicotinamide adenosine dinucleotide (phosphate)
an important consequence of the ETC is the formation of a __________ __________
proton gradient
during oxidation of NADH, protons are transported _____ ___ the cell. they ________ the cell through ATP synthase and generate ATP
out of; re-enter
reactions can be linked together to form ______________ __________
biological pathways
what are three biological pathway orientations?
- linear
- cyclic
- branched
what are enzymes?
molecules that speed up reactions
enzymes can be made from ________ or _____ (___________)
protein or RNA (ribozymes)
what are protein catalysts?
highly specific substrates that increase the rate of a rxn without being permanently altered
what are substrates? products?
- substrates: reacting molecules
- products: substances formed by the reaction
what is an apoenzyme?
the protein component of an enzyme
what is a cofactor?
non-protein component of an enzyme
what are two types of cofactors?
- prosthetic group: firmly attached
- coenzyme: loosely attached; can act as carriers/shuttles
what is a holoenzyme?
apoenzyme + cofactor
what are the six general classes of enzymes?
- oxidoreductases
- transferases
- hydrolases (breakdown using water)
- lyases (breakdown w/o water)
- isomerases
- ligases
what does the transition state complex resemble in a reaction?
it resembles both the substrates and the products
what is the activation energy of a reaction?
the energy required to form the transition state complex
how do enzymes speed up reactions?
by lowering the activation energy (Ea)
what are three environmental factors that significantly impact enzyme activity?
- substrate concentration
- pH
- temperature
what are the effects of substrate concentration on enzyme activity?
- the rate of a rxn increases as the substrate conc. increases
- it stops increasing when all enzyme molecules are saturated with substrate
how do pH and tempertaure affect enzyme activity?
the enzyme can be denatured if the pH or temp goes outside its specific range that it can tolerate
what are the three important mechanisms of metabolism for conservation of energy?
- metabolic channeling
- regulation of the synthesis of a particular enzyme (transcription or translation)
- direct stimulation or inhibition of the activity of the activity of a critical enzyme (post-translational)
what is compartmentation?
differential distribution of enzymes and metabolites among other cell structures and organelles
what the the two types of reversible post-translation regulation of enzyme activity?
- allosteric regulation
- covalent modifications
what is an allosteric effector?
a small molecule that non-covalently binds to the regulatory site, changing the shape of the enzyme and altering its catalytic activity
- positive effector: increases enzymatic activity
- negative effector: inhibits
what is covalent modification of an enzyme?
- addition or removal of a chemical group (example: phosphate, methyl, adenylyl)
- reversible on and off switch
what is feedback inhibition (end-product inhibition)?
when the product builds up and inhibits the pathway
what is a pacemaker enzyme?
an enzyme that catalyzes the slowest step/rate-limiting reaction in a pathway
