Energy, Catalysis & Biosynthesis - Cell Bio Test 2
ΔG° (standard free energy) is independent of concentration; it depends only on the intrinsic characters of the reacting molecules, based on their behavior under ideal conditions where the concentrations of all reactants are set to the same fixed value. What is this fixed concentration?
1 mole/liter
Energy cannot be created or destroyed, but it can be converted from one form to another. What is this?
1st law of thermodynamics
The activated carriers of photosynthesis are?
ATP & NADPH
The universal tendency of things to become disordered. In the universe or in any isolated system, the degree of disorder can only increase. What is this law?
The 2nd law of thermodynamics
In any reaction in which electrons are transferred from one atom to another. This is the removal of electrons from an atom. What is this called?
oxidation
In both plants & animals, energy is extracted from food molecules by a process of controlled burning or gradual?
oxidation
When two atoms form a polar covalent bond, the atom that ends up with a lesser share of electrons is said to be?
oxidized
If an atom loses an electron, it has been ?
oxidized (Fe+ is oxidized when it loses an electron to become Fe3+)
Solar energy enters the world through?
photosynthesis
This is a process that converts the electromagnetic energy in sunlight into chemical-bond energy in cells.
photosynthesis
The higher the concentration of reactants, the greater the?
rate of a reaction (If you want a reaction to go faster, put in more reactants)
ΔG (Delta G) is concentration dependent. Even if we have an unfavorable reaction, we can force a reaction by adding?
reactants
When two atoms form a polar covalent bond, the atom that ends up with a greater share of electrons is said to be ?
reduced
If an atom gains an electron, it has been?
reduced (chlorine is reduced when it gains an electron to become Cl-)
This involves the addition of electrons to an atom
reduction
Energetically unfavorable reactions create order in the universe; they have a positive ΔG. Such reactions cannot occur spontaneously. They take place only when coupled to a ?
second reaction with a negative Delta G large enough that the net Delta G of the entire process is negative
Since there is no no net loss or gain, oxidation & reduction always occur when?
simultaneously (If one molecule gains an electron in a reaction (reduction), a second molecule must lose the electron (oxidation))
Unlike the effects of temperature, enzymes are highly selective. Each enzyme speeds up only one particular reaction out of the several possible reactions that its substrate molecules could undergo. In this way, enzymes direct each of the many different molecules in a cell along what?
specific reaction pathways (producing the compounds that the cell actually needs)
In the second stage of photosynthesis, the activated carriers are used to help drive a carbon-fixation process, in which sugars are manufactured from carbon dioxide gas, creating what?
stored chemical-bond energy
During catalysis, each enzyme binds tightly to one or two molecules and holds them in a way that greatly reduces the activation energy needed to facilitate a specific chemical interaction between them. What are these molecules to which enzymes bind?
substrates
The fact that chemical reactions tend to equilibrium, implies what?
that all reactions are reversible
ΔG (Delta G) measures?
the amount of disorder created in the universe when a reaction takes place
In the law of mass action, the reaction rate is proportional to what?
the concentration of reactants
Whether a reaction will proceed depends not only on the energy stored in each individual molecule, but also on?
the concentrations of the molecules in the reaction mixture
Movement toward disorder is a spontaneous process, requiring a periodic input of energy to reverse it. The measure of a system's disorder is called?
the entropy of the system (the greater the disorder, the greater the entropy)
What is used to find the equilibrium of a reaction?
the equilibrium constant, K (K =(X product)/(Y reactants)
As K gets larger = bigger drop in free energy between the dissociated & associated states, consequently what happens during molecular binding?
the more tightly two molecules will bind
Knowing where an equilibrium lies for any given reaction will tell you what?
which way the reaction will proceed and how far it will go
If reactants are greater than products, then the reaction will or will not proceed?
will proceed
When a molecule in a cell picks up an electron, it often picks up what at the same time in water?
a proton (H) (such hydrogenation reactions are still reductions)
In stage one of photosynthesis, kinetic energy of a photon is captured (energy from the sunlight is captured) and transiently stored as chemical bond energy in specialized molecules called?
activated carriers (All of the oxygen in the air we breathe is generated by the splitting of water molecules during this first stage of photosynthesis.)
A molecule requires a boost over an energy barrier before it can undergo a chemical reaction that moves it to a lower energy state. This boost is known as?
activation energy
Even if ΔG° (standard free energy) is >0 (greater than zero), a large excess of reactants will give ΔG <0 (a less than zero figure). In other words, we can force an unfavorable reaction by?
adding a large excess of reactants (Why? B/c we are moving AWAY from equilibrium by doing this)
ΔG° (the standard free energy )change is NOT dependent on concentrations and is used to predict whether an energetically favorable reaction is likely to have a ΔG negative enough to drive what?
an energetically unfavorable reaction
In this pathway, the energy harnessed by catabolism is used to drive the synthesis of the many molecules that form the cell. What is this pathway?
anabolic pathway (biosynthetic pathway)
All animals live on energy stored in the chemical bonds of food. These food molecules also provide ?
atoms to construct new living matter
Life is possible because enzymes can create biological order by coupling energetically unfavorable reactions with?
energetically favorable ones
Enzymes can speed up energetically favorable reactions in cells. They cannot; however, by themselves force what to occur?
energetically unfavorable reactions
Inside cells, the push over the energy barrier is aided by specialized proteins called?
enzymes
Most of the chemical reactions that cells perform would normally occur only at temps much higher than those inside a cell. Consequently, each reaction requires a major boost to enable it to proceed rapidly inside a cell. This boost is provided by specialized proteins called?
enzymes
Basically, ΔG represents how far away you are from?
equilibrium
Because ΔG changes as products accumulate & substrates are depleted, chemical reactions will generally proceed until they reach a state of?
equilibrium
The useful energy in a system is known as its?
free energy
A cell is not an isolated system. It takes in energy from its environment in the form of food, inorganic molecules or photons of light from the sun & then uses this energy to generate order w/i itself forging new chemical bonds & building large macromolecules. In the course of performing chemical reactions that generate order, some energy is lost in the form of?
heat
This is energy in its most disordered form
heat
A chemical reaction can proceed only if it results in a net (overall) ?
increase in the disorder of the universe
An easy way to tell whether a molecule is being oxidized is to count its C-H bonds: reduction occurs when the number of C-H bonds increases or decreases?
increases
The amount of heat released by a cell must be great enough that the increased order generated inside the cell is more than compensated for by the increased disorder generated in the environment. Only then, is the 2nd law of thermodynamics satisfied, b/c the total entropy of the system - that of the cell + its environment does what?
increases as a result of the chemical reactions inside the cell
The more product you have, the greater the strength of?
interaction
ΔG for a reaction, not only depends on concentrations, but also on the?
intrinsic properties of molecules (energy of reactants)
The free energy change for a reaction, determines whether?
it can occur
Chemical reactions proceed only in the direction that leads to a?
loss of free energy
Enzyme- catalyzed reactions are usually connected in series, so that the product of one reaction becomes the starting material for the next. This forms a what?
metabolic pathway
Catalysis is a benefit to the cell. It allows the cell to control its?
metabolism
This is the sum total of all the chemical reactions a cell needs to carry out - to survive, grow & reproduce, central to the chemistry of life.
metabolism
The cell cannot derive any benefit from the heat energy it produces unless the heat-generating reactions are directly linked to processes that maintain?
molecular order inside the cell (It is the tight coupling of heat production to a increase in order that distinguishes the metabolism of a cell from the wasteful burning of fuel in a fire.)
When an animal cell breaks down food, some of the energy in the chemical bonds in the food molecules is converted into the thermal motion of molecules or heat energy. This conversion of chemical energy into heat energy causes the universe as a whole to become?
more disordered
A reaction can occur spontaneously, only if ΔG is?
negative
Energetically favorable reactions, create disorder by decreasing the free energy of the system to which they belong. In other words, they have a?
negative Delta G (ΔG)
For reactions at chemical equilibrium, ΔG = 0, so the reaction will not proceed forward or backward. What does this mean concerning work?
no work can be done (Such a state would be incompatible with life. Living cells are constantly exchanging materials w/their environment, replenishing nutrients & eliminating waste.)
The equilibrium constant K, is commonly employed as a measure of the binding strength of a?
noncovalent interaction between two molecules (K becomes larger as the binding energy that is released in the binding interaction increases)
In this pathway, the breaking down of foodstuffs into smaller molecules happen, generating energy for the cell & small molecules the cell needs as building blocks. Which pathway is this?
catabolic pathway
Metabolism is made up of two opposing streams of chemical reactions that occur in cells. What are they?
catabolism & anabolism
Enzymes promote?
catalysis
This is the acceleration of the specific chemical reactions needed to sustain life
catalysis
A cell is able to obtain energy from sugars or other organic molecules by allowing the carbon & hydrogen atoms in these molecules to combine with oxygen (that is become oxidized) to ultimately produce CO2 & H2O. This process is known as?
cellular respiration
ΔG is not only represents free energy, but it is a measurement of?
chemical bond energy
In this state of the reaction, the rates of the forward & reverse reactions are equal and there is no further net change in the concentrations of substrate or product. What is this state?
chemical equilibrium
Oxidation occurs when the number of C-H bonds increases or decreases?
decreases
Disorder increases when useful energy that could be harnessed to do work is?
dissipated as heat
