Bioenergetics Flashcards
What is Energy?
Capacity to do work (or heat or anything that can be transformed into heat)
What are some forms that energy exists in?
heat, light, electric, mechanical, chemical, nuclear
etc.
What is Kinetic Energy?
the energy of motion, or the form of energy that is actually doing work.
Ex. Kinetic energy in heating due to movement of molecules in matter
Ex. Falling water from a waterfall has kinetic energy because of the mass of water in motion.
What is Potential Energy?
a form of stored energy, the capacity to perform work.
Ex. Water behind a dam has potential energy due to position at a higher level.
Ex. Fossil fuels (hydrocarbons like gasoline or carbon like coal) also have stored potential energy (chemical energy) which is released when they are burned in a combustion engine
What is Chemical Energy?
all chemical molecules store energy
The different molecules have various potential energy due to the arrangement of their atoms.
Potential energy due to particular arrangement of atoms in energy rich food like sugars and fats can be released by allowing certain chemical reactions to rearrange those atoms to a lower energy configuration like CO2 and H2O.
What is the First Law of Thermodynamics? The law of Energy Conservation.
the total amount of energy in the universe remains constant.
➢ Energy can be changed from one form to another.
➢ However, energy is neither created not destroyed in a closed system.
What is the Second Law of Thermodynamics? The law of energy conversion.
reducing the order of the universe, increasing its entropy (randomness - the
amount of disorder in a system).
➢ The spontaneous direction of energy flow is from forms organized (rich energy) to less organized (less energy).
➢ The amount of ‘lower quality’ energy in the universe is increasing.
➢ Energy changes are not 100% efficient.
➢ Some energy is always lost as heat.
➢ Without energy input, any organized system tends to get disorganized over time.
What is cellular metabolism?
the sum of chemical activities within a living cell.
What are metabolic pathways?
sequences of enzyme-catalyzed reactions.
What is anabolism?
refers to the various pathways in which complex molecules are synthesized
from simple substrates.
What is catabolism?
includes the pathways in which larger molecules are broken down into smaller ones
What is free energy?
(ΔG)is the amount of a system’s energy that can perform work when temperature and
pressure are uniform throughout the system, as in a living cell
What is a spontaneous reaction?
a chemical reaction which will proceed on its own, without any outside influence
What is an exergonic reaction?
an energy-releasing chemical reaction yielding products that contain less potential
energy than their reactants.
What is an endergonic reaction?
an energy-requiring chemical reaction yielding products rich in potential energy.
What is an energy coupling reaction?
the use of energy released from exergonic reactions to drive essential endergonic reaction.
What is the energy of activation?
the amount of energy that reactants must absorb before a chemical reaction will start. This represents the energy barrier that prevents molecules from breaking down spontaneously.
What is the role of enzymes?
They lower the activation energy of specific biochemical reactions
What is an enzyme?
a protein that serves as a biological catalyst
What is a catalyst?
any substance which can lower the energy of activation
What is the ATP cycle?
Continued breakdown and resynthesis of ATP
What is the active site?
the region on the surface of an enzyme where the substrate binds, and where catalysis occurs.
What are cofactors?
inorganic ions such as iron, copper or zinc that bind to certain enzymes.
What are coenzymes?
small carbon-containing molecules such as Coenzyme A (CoA), NAD, FAD or
ATP which are not permanently bound to the enzyme, and must collide with the enzyme and bind
to its active site before the catalytic reaction occurs.
What is a prosthetic group?
distinctive molecular groups that are permanently bound to their enzymes such as heme or flavin.
What regulates enzyme activity?
inhibitors, pH, temperature, etc.
What is competitive inhibition?
Inhibition of an enzyme reaction by an inhibitor molecule that resembles the normal substrate closely enough that it fits into the active site of the enzyme.
What is ATP
Adenosine triphosphate - The energy currency of the living cell.
How do living cells store energy?
in chemical bonds of lipid, starch and glycogen
What do cells use for immediate energy?
ATP. It gets used and must be replaced immediately
What is the structure of ATP?
a nucleotide consisting of 3 parts
- Adenine - a nitrogen containing organic base
- Ribose - a five carbon sugar
- three phosphate groups.
What is the function of ATP?
Exergonic reaction (hydrolysis)
ΔG = -7.6 kcal/mole.
➢ Energy liberated can drive a variety of cellular processes.
➢ When the terminal phosphate is removed from
ATP, the remaining molecule is adenosine
diphosphate (ADP).ATP + H2O ADP + Pi + ∆G (= -7.6 kcal/mol)
➢ If the phosphate group is not transferred to
another molecule, it is released as inorganic
phosphate, which is an exergonic reaction.
What are the 2 ways ATP can be generated?
Substrate-Level Phosporylation
Chemiosmosis
What is substrate-level phosporylation?
ATP is formed when a phosphate group is transferred to ADP from a phosphorylated intermediate.
What is chemiosmosis?
process by which
phosphorylation of ADP to form ATP is coupled to the transfer of electrons down an electron transport chain.
What is oxidative phosphorylation?
ATP synthesis driven by electron transfer to oxygen.
What is Photophosphorylation?
ATP synthesis driven by light
What is oxidation?
the chemical process in which a substance loses electrons
The substance that becomes oxidized gives up energy as it release electrons
What is reduction?
the chemical process in which a substance gains electrons
The substance that becomes reduced receives energy as it gains electrons
The electron transport chain happens in the final stage of cellular respiration which is called __________________?
oxidative phosphorylation
What are the membranes and compartments of the mitochondrion?
Outer mitochondrial membrane
Inner mitochondrial membrane
Matrix
Intermembrane compartment
The diagram and summary of glycolysis
What happens in the first step of the citric acid cycle?
Pyruvate (three carbons) is oxidized to an acetyl group (two carbons), which is carried to the citric acid cycle by CoA. The third carbon is released as CO2. Accepts two electrons and one proton removed in the oxidation
What drives electron transport?
the prosthetic groups and other electron carriers are organized in a very specific way: from high to low free energy. NADH has high potential energy because it contains high-energy electrons and thus can be readily oxidized.
