The totality of n organism's chemical reactions.
Begins with a specific molecule, which is altered in a series of define steps, resulting in a certain product. Each step is catalyzed by specific enzyme.
A metabolic pathway that releases nergy by breaking down complex molecules to simpler compunds.
Major pathway of catabolism
A metablic pathway that consumes energy to synthesize a complex molevule from simper compounds.
The tudy of how energy flows through living organisms.
Capacity ro cause change.
Energy associated with the relatie motion of objects.
Heat/ thermal energy
Energy that matter posseses because of its location or structure.
Potential enegy available for release in a chemical reaction.
During catabolic reaction
Atoms are rearranged and energy is released, resulting in lower energy breakdown products.
The study of energy tranformations that occur in a collection of matter.
The word "system" is used to
Denote the matter under study.
Unable to exchange energy or matter with surroundings.
In an open system
Energy and matter can be transferred bteen the system and its surroundings.
First law of dynamics
Energy can be transferred and transformed bu can't be created or destroyed. Also known as the principle of energy.
A system can put heat to work only when
There is a temperatures difference that results in the heat flowing from a warme location to a cooler one.
Measure of disorder or randomness.
Second law of Thermodynamics
Every energy transformation increases the entropy (disorder) of the earth.
Entropy is evident in
The physical integration of a system's organized structure.
For process to occue on its own, it
Must increase entropy of the earth.
When process can't occur on its own.
Engy must be
Added to system for process to occur on its own.
Depletion of chemical energy is accounted for by
Heat generated during metabolism.
Energy flows into ecosystem
In form of light, exits in the form of energy.
Thesystem plus is surroundings.
Entropy of particular system
May actually decrease as long as the entropy of the universe increases.
Islands of low entropy in an increasingly random universe.
The portion of a system's energy that can perform work when temperature and pressure are uniform throughout the system, as in a living cell.
Free energy can be calculated with
Free energy = total energy-enthalpy-absolute temperature in Kelvin units.
Once you know the amount of free energy
Use it to predict whether the process will be spontaneous.
For it to be spontaneous
Process must give up enthalpy (H must increase), give up order or both.
Every spontaneous process
Decreases the system's free energy.
Processes wth positive or zero
Are never spontaneous.
Free energy equals
Final state - Initial final state.
Tend to change in such a way that they become stabler.
For system at equilibrium
'G' is at its lowest possible value in that system.
Any chnge from equilibrium position
Will have positive G ans will not be spontaneous, so system never spontaneously move away from equilibrium.
Process is spontaneous and
Can perform work only when it is moving toward equilibrium.
Proceeds with a net release of energy. Is spontaneous.
Because chmical mixture loses free energy
'G' decreaes so G is negative for an exergonic reaction.
For each mole of lucose broken down by respiration
Under standard condition 686 kcal of energy and made available for work.
Absorbs free energy from it surroundings. It is nonspontaneous since its 'G' is positive.
In endogonic reaction, the magnitude of 'G' is
The quantity of energy required to drive the reaction.
Reversible chemical process cannot
Be uphill or downhill in both directions.
Reactions in isolated system
Eventually reach equilibrium and can do no work.
Since systems at equilibrium are at a minimum of G.
They can do no work so a cell that has reached equilibrium is dead
Metabolism is never
Some of the reversible reactions of respiration
Are kept out of equilibrium
Key to maintaning lack of eqilibrium
Is that prduct of a reaction does not accumulate, but instead becomes reactant in next step.
Glucose and oxygen are
At the top of the energy "hill" and carbon dioxide and water are at the "downhill" end.
A cell does 3 kinds of work
Chemical work, the pushing of endergonic reactions.
Transport work, the pumping of substances across membranes against the direction of spontaneous movement.
Mechanical work, such as the beating of cilia and muscle contraction.
Useof exergoic process to drve endergonic one.
The sugar ribose, with he nitrogenous base adenine and a chain of three phosphate groups bonded to it.
The bonds between the phosphate groups of ATP
Can be broken down by hydrolysis.
The reaction ATP turning to ADP is an
Exergonic reaction and releases 7.3 kcal of energy per mole of ATP hydrolyzed.
In cell, conditions don't conform to standard conditions because
Reactant and product concentrations differ from 1M.
The phosphate bonds of ATP are called "high energy" because
The reactants (ATP and water) hve high energy relative to the energy of the products (ADP and inorganic phosphate).
Produces free energy which produces heat.
A molecule that's covalently bonded to a phosphate group.
phosphorylated formation is
Key to coupling exergonic and endogonic reactions since it is more reactive (less stable) than the original unphosphorylated molecule.
ATP is a
Renewable resource that can be regeneraed by the addition of phosphate to ADP.
The free energy required to phosphorylate ADP
Comes from exergonic breakdown reaction (catabolism) in the cell.
This shuttling of inorganic phosphte and enery that couples the cell's energy yielding (exergonic) processes to the energy-consuming (endergonic) ones.
Regeneration of ATP from APD and inorganic phosphate is
Endergonic. Free energy must be spent for this to occur. Catabolic (exergonic) pathways, especially cellular respiration provide energy for the endergonic process of making ATP.
The chemical potential energy
Temporarily stored in ATP drives most cellular work.
Spontaneous chemical reaction occurs
By itself but it may occur so slowly that it is impenetrable.
Acivation energy (eA)
The amount of energy that a reactant must absorb before a chemical reaction will start; also caled free energy of activation.
When reactants are in an unstable condition after being activated.
Absorption of thermal energy
Increases the speed of the reactant molecus so they collide more often and more forcefully.
Heat speeds reaction by
Alowing reactants to attain the transition state more often but this solution is inappropriate for biological systems. Heat denatures protein and won't discrimminate in which reaction it heats.
Enzyme catalyzes reaction by
Lowering eA barrier, enabling the reaction molecules to absorb enouh energy to reach the transition state even at moderate temperatures.
Hasten reactions that would occur eventually but this function makes it possible for the cell to have dynamic metabolism, routing chemicals smoothly hrough cell's metabolic pathyways.
Determine which chemical processes will be going on in thecell at any particular time.
The reactant an enzyme acts on. The two bind forming an enzyme-substrate complex.
Temporary complex formed when enzyme binds to its substrate molecule.
While enzymes and substrates are together
The catalytic action of the enzyme converts substrate to the product of the reaction.
Reaction catalzed by ach enzyme is
Specificity of an enzyme
Results from its shpe, which is a consequence of its amino acid sequence.
The specific portion of an enzyme that binds the substrate by means of multiple weak interatons that forms the packet in which catalysis occurs.
Specificity of an enzyme is attributed to
A compatible fit between te shae of its active site and the shape of the substrate.
Amino as form
The active site of the protein.
A substrate enters
The active site and then the interactions between its chemical groups and those on the R groupse (side chains) of the amino acids that form active side of protein, causing enzyme to change slightly so active site fits more snugly around substrate.
Induced by entry of substrate, the change in shape of the active site of an eenzyme so that it binds more snug to the substrate.
Enzymes emerge from reaction
In their original form, so small amounts of enzyme can have a huge metabolic impact by functioning again and again in catalytic cycles.
Because activation energy is propoiol to the difficulty of breaking the bonds
Distorting the substrate helps it approach the transition state, reducing the amount of free energy that must be absorbed to achieve that state.
At some point, concentration of substrate will be
High enough that all enzyme molecules have their active sites engaged.
When enzyme saturated
The rate of the reactionis determined by the speed at awhich the active sit converts substrate to product.
When enzyme population is satrated, only way to increase rate of prodution is to
Add more enzyme.
Up to a point th rate of an enzymatic reaction
Increases with increaing termperature, artly because substrates colide with active sites more frequently when the molecules move rapidly.
Above certain temperature
Enzymatic reaction drops sharply.
Most human ezymes have
Optimal temperatures of about 35 to 40 degrees celcius.
Optimal pH for most enzymes
However some enzymes ke pepsin (digestive enzyme in human stomach
Work best at pH 2. Pepsin is adapted to maintain its 3D shape in stomach's acidic environment.
Digestive enzyme in human intestine which has optimal pH of 8.
Any nonprotein molecule or ion that is required for the proper functioning of an enzyme. Can be permanently bound to active site or may bind loosely with the substrate during catalysis.
Organic molecule serving as a cofactor. Most vitamins function as cenzymes in metabolic reations.
A substance that reduces the activity of an enzyme by entering the active site in place of the substrate.
A substance that reduces the activity of an enzyme by binding to a location remote from the active site, changing the enzyme's shape so that the active site no longer functions effectively.
Toxins and poisons
Are often irreversible enzyme inhibitors.
Molecules naturally in cells
Often act as inhibitors.
When a protein's function at one site is affected by the binding of a regulatory molecule to a separate site. May be result in either inhibition or stimulation of an enzyme's activity.
The binding of an activator to a regulatory site
Stabilizes the shape that has functional active sites, whereas the binding of an inhibitor stabilize the inative form of an enzyme.
Through interaction of subunits
A single activator or inhibitor molecule that binds to one regulatory site will affect the active site of all subunits.
ATP binds to
Several catabolic enzymes allosterically, lowering their affinity for substrate and this inhibiting their activity.
ADP functions as
Activator of the same enzymes ATP inhibits.
If ATP production lags behind use
ADP accumulates and activates the enzymes that speed up catabolism, producing more ATP.
If ATP supply exceeds demand
Then catabolism slows down as ATP molecules accumulate and bind thses same enzymes and inhibits them.
A kind of allosteric regulation whereby a shape change in one subunit is transmitted to all the others, facilitating binding of subsequent substrate molecules.
Isn't an enzyme but is example of cooperactivity.
Example of cooperactivity
First enzyme in the pathway for pyrimidine biosynthesis in bacteria.
Allosteric regulatory molecules are
Hard to chracterize because they tend to bind the enzyme at low affinity and are hard to isolate.
Allosteric regulatory molecules
Are attractive to drug candidates for enzyme regulation because they exhibit higher specificity for particular enzymes than do inhibitor that bind to the active site.
Protein-digesting enzymes that play an active role in inflammation and cell death.
A method of metabolic control in which the end product of a metabolic pathway acts on inhibitor of an enzyme within that pathway.
In eukaryotic cells, the enzymes for cellular respiration
Reside in specific locations within the mitochondria.
Some enzymes and enzyme components
Have fixed locations within the cell and act as structural components of particular membranes.
Other enzymes are
In solution within specific membrane enclosed eukaryotic organelle, each with its own internal chemical environment.
Enzymes speed up the rate of reaction by
Decreasing the free-energy of activation.
Hypothermia - Mild - 90-95F
Increased heart rate, impaired coordination, shivering, inattentiveness, decreased motor activity, fatigue.
Hypothermia - Severe- Below 81F
Inability to follow commands, loss of consciousness, decreased ability to walk.
Metal ions - Zn++, Mn++, Mg++, Cu++, and Fe++
Help enzymes catalyze reactions.
Transfers atom, electron, or functional groups to different substrates
Nucleotides that aid enzyme action.
Accepts electrons and hydrogen atoms and transfers them to reaction sites.
NAD, FAD, NADP.
The movement of molecules from a higher to a lower concentration.
The movement of molecules from a higher to a lower concentration through a semi-permeable membrane.
The movement of water from a higher to a lower concentration through semi-permeable membrane.
Them movement of molecules from a lower to a higher concentration thrugh a semi-permeable mebrane with the expenditure of energy.
Equal concentration of solute and water
High concentration of solute and lower concentration of water.
Higher concentration of water and lower concentration of solute.
Ion's concentration gradient - Difference in number of ions.
The charge (voltage) difference between a cell's cytoplasm and the extracellular fluid.
Required Transport proteind and ATP.
Move against diffusion gradient.
Requires transport proteins.
High Substrate specificity.
Regulated channel proteins.
Function of cell membrane
Separate the living cell from the nonliving environment. Protection.
Function of cell membrane
Play on an active role in the movement of substances into and out of the cell.
Function of cell membrane
Sense and interact with the external environment (hormones and growth factors).
Fucnction of cell membrane
Maintain structural and chemical relationship of the cell.
Nature of membrane: The composition
-Phoshoplipid Bilayer (amphipathic)
Example of endocytosis?
Large molecules are transported through
Endocytosis, exocytosis, phagocytosis, pinocytosis, and receptor mediated endocytosis.