Bioenergetics and Enzymes Flashcards
Metabolism
chemical reactions which organisms acquire and use energy and transform materials
catabolic pathways
release energy by breaking down complex molecules into simple molecules
anabolic pathways
absorb energy by using simple molecules to build complex molecules
energy that can do work in the cell (free energy)
chemical- synthesizing polymers from monomers
transport- pumping substances across the membranes
mechanical- beating of cilia and muscle contraction
energy that cannot do work (thermal)
never 100% effienct
Free energy
can perform work when thermal and pressure are uniform through the system
spontaneous reaction
releases free energy (G will be negative) and exergonic (energy outwards), free energy lost, downhill
non-spontaneous reaction
absorbs free energy (G will be positive) and endergonic (energy inward), will not proceed unless coupled with an outside process that supplies energy
Exergonic
releases energy, and produces more reactant potential energy then the products
Endergonic
absorbs energy, and have products with more potential energy then reactants
Cellular Metabolism
sum of endergonic and exergonic reactions in the cell
Energy coupling
using energy released from exergonic reactions to drive endergonic reactions
Kinetic energy
contains a moving mass or particles
energy transferred through a work place its involved
chemical energy
flow of charged particles
mechanical energy
energy in mechanical devices
light energy
harnessed in photosynthesis
Potential energy
stored engery
chemical energy
stored in molecular bonds
Bond energy: chemical bonds take the same amount to break as to release energy
Living Cells
stored energy on atomic bonds of food
release stored energy slowly through respiration
ATP
energy carrier in cells - energizes molecules by phosphorylating them
Hydrolysis of ATP is an?
Exergonic process
- ADP and Pi are more stable (less free energy) than ATP because charge repulsion
- stabilization of inorganic phosphate group
- loss of H+ by terminal phosphate group on ADP
- enhanced hydration of the products of the reaction compared to the reactants
- ATP has high activation energy therefore enzyme is needed for hydrolysis to occur at a rapid rate
ATP synthesis is an ?
Endergonic process
- requires energy
- hydrolysis yields
What happens when endergonic process and ATP hydrolysis are coupled?
reaction would be exergonic and spontaneous
Because
-hydrolysis doesn’t provide heat, phosphorylation does
- ATP hydrolysis only heats surrounding
-ATP hydrolysis provides own energy without phosphorylation and is bound tightly at the myosin head, then hydrolyzed, and the head changes position while ADP and Pi are released
Enzymes are proteins that catalyze biochemical reactions
- lower activation energy of reactions makes reactions go faster
- doesn’t change G of reaction
Enzymes are specific
one or few substrate (enzyme works on)
Enzymes have active sites
(small part of enzyme to bind to substrate)
Induce fit: substrate binding causes a change in the shape of the active site
Enzyme can lower activation energy by
- holding reactants in position to promote reaction
- provide suitable micro-environment
- employing amino acid side chains in the active site for covalent bond reorganization
- Enzyme regenerates during reaction (further catalytic cycles) but not indefinitely (enzymes have half life)
Affecting enzymes : Substrate concentration
- too little substrate= active sites arent occupied enough
- too much substrate= not enough active sites avaliable
Affecting enzymes : Temperature
- high= high rate of enzyme reaction
-too high= enzyme denatures (broken down)
Enzyme has an optimal temperature
Affecting enzymes : pH
- optimal pH 6-8
- extreme pH = enzyme denatures (breaks down)
Cofactors
small, non-proteinaceous molecules required by most enzymes for their catalytic activity
- may bind tightly or loosely to active site or enzyme
- some organic eg. coenzyme
- some inorganic eg. metals
Inhibitors and Activators; Competitive inhibitors
resembles enzymes normal substrate and competes with substrates for active site
Inhibitors and Activators; Non-Competitive inhibitors
does not enter active site but binds elsewhere
Feedback inhibition
product pathway inhibits the first enzyme of a pathway
Negative Feedback
(metabolic path or hormone-secreting gland) is inhibited by the product of the reaction, gland or path as the concentration builds up the product molecules inhibit the process that produced them
