Unit 3: Cellular Energetics Flashcards
Metabolism
totality of an organisms chemical reactions; arises from orderly interactions between molecules
catabolic pathways
release energy by breaking down complex molecules into simpler compounds
ex) cellular respiration breaks down glucose
anabolic pathways
consume energy to build complicated molecules from simpler ones
ex) synthesis of an amino acid from simpler molecules and then the synthesis of a protein from amino acids
Exergonic Reaction
proceeds with a net release of free energy
G is negative
spontaneous (does not require energy to begin), so energetically favorable
ex: cellular respiration
endergonic reaction
absorbs FREE energy from its surroundings
G is positive
stores energy, non-spontaneous
ex: photosynthesis
What is ATP made of?
nucleotides: a triphosphate group, adenine base, phosphate group, and ribose
holds energy in its chemical bonds between the phosphate groups
ATP is recyclable after it loses a phosphate (releasing energy), the cell recharges by adding another
Hydrolysis is the process in which the bond breaks by the addition of a water molecule.
catalyst
chemical agent that speeds up a reaction without being consumed by it
Activation Energy
the energy that reactants must absorb before a chemical reaction will start also called free energy of activation
enzymes lower the Ea barrier and enable the reactant molecules to absorb enough energy to reach the transition state even at moderate.
Induced fit
tightening of binding after initial contact.
brings chemical groups of the active site into positions to enhance their ability to catalyze the chemical reaction.
what affects the rate of enzyme action
- initial concentration of substrate: the more substrate available, the more frequently they can be pushed by adding more substrate to a fixed amount of enzyme. at some point, the concentration of substrates will be high enough that the enzyme molecules will be maxed out
- pH- change in pH levels can denature most enzymes
- temperature- up to a point, the rate of an enzymatic reaction increases with temperature partly because substrates collide with active sites more frequently when the molecules move rapidly. Above that temp, the speed of enzymatic reaction drops. Thermal agitation disrupts the hydrogen and ionic and other weak bonds.
Cofactors
any nonprotein molecule or ion that is required for the proper functioning an enzyme
can be permanently bound to the active site or may bind loosely and reversibly along with the substrate
ex: inorganic, metal atoms like zinc, copper and iron
coenzymes
an organic material serving as a cofactor. most vitamins function as coenzymes in metabolic reactions
ex: most vitamins are important in nutrition because they act as coenzymes or raw materials from which coenzymes are made
competitive inhibitors
Competitive inhibitors reduce the productivity of enzymes by blocking substrates from entering active sites. They can be overcome by increasing the concentration of a substrate so that as active sites become available, more substrate molecules than inhibitor molecules are around to gain entry to the sites.
noncompetitive inhibitors
Noncompetitive inhibitors do not directly compete with the substrate to bind to the enzyme at the active site. They impede enzymatic reactions by binding to another part of the enzyme. This interaction causes the enzyme molecule to change its shape in such a way that the active site becomes much less effective at catalyzing the conversion of a substrate to a product.
allosteric regulation
describes any situation in which a protein’s function at one site is affected by the binding of a regulatory molecule to a separate site. may result in either inhibition or enzyme stimulation
