Energy and Metabolism (Chapter 6) Flashcards
The significant properties by which we define life are
Order, growth, reproduction, responsiveness, and internal regulation.
The significant properties by which we define life requires a constant supply of
energy
bioenergetics
the analysis of how energy powers the activities of living systems.
1.What is Thermodynamics? 2.What does the term mean?
- A branch of chemistry concerned with energy changes. 2. “Heat changes”
The study of transformations of energy, using heat as the most convenient form of measurement of energy.
Thermodynamics.
Energy
The capacity to do work.
Energy exists in two states, which are:
1) Kinetic energy 2) potential energy
Kinetic energy
energy in motion
potential energy
stored energy; energy that is not being used, but could be.
Objects that are not actively moving but have the capacity to do so possess what form of energy?
potential energy Example: A boulder at a hilltop; or a child sitting at the top of a slide
Stored potential energy is released as what form of energy?
Kinetic Energy Ex: Child going down a slide.
Name 6 forms of energy
mechanical heat sound electric light radioactive
What form of energy is the most convenient way of measuring energy?
Heat
Unit of heat most commonly employed in biology
kilocalorie (kcal)
1 kilocalorie =
1000 calories
1 calorie =
the amount of heat required to raise the temperature of water one degree Celsius.
1 joule =
0.239 calories
What provides energy for living systems?
the sun
Energy flows into the biological world from t
the sun
Plants, algae, and certain bacteria capture energy through
photosynthesis
What occurs in photosynthesis?
- Energy is absorbed form sunlight. 2. Energy absorbed is used to combine small molecules (water + carbon dioxide) 3. Carbon is converted from inorganic to organic form. 4. Energy from sunlight is stored as potential energy in the covalent bonds between atoms in sugar molecules.
Breaking bonds between atoms requires
energy
During a chemical reaction, the energy stored in chemical bonds can be used to make what?
new bonds
When is an atom or molecule said to be oxidized?
when electrons are lost
Oxidation (process)
Loss of an electron by an atom or molecule.
What is the most common electron acceptor in biological systems?
Oxygen
When is an atom or molecule said to be reduced?
when electrons are gained
Reduction (process)
gain of electrons by an atom or molecule
What form of a molecule has the higher level of energy, the reduced form or the oxidized form?
reduced form
Oxidation-reduction, or redox reaction
A type of paired reaction in living systems in which electrons are lost (oxidation) by one atom and gained by another atom (reduction) ** oxidation and reduction always take place together.
True or False All activities of organisms– growing, running, thinking, singing, reading, involves changes in energy.
true
The first law of thermodynamics states that
The total amount of energy in the universe remains constant; as energy cannot be created or destroyed, it can only change from one form to another (potential to kinetic).
What is heat? Heat is a form of what type of energy?
- A measure of the random motion of molecules, the greater the heat the greater the motion. 2. Kinetic energy
During the conversion of chemical potential energy stored in some molecules, some of the energy dissipates into the environment as
heat
Heat can be harnessed to do work only when there is a
heat gradient; that is, a temperature difference between two areas.
Is heat energy capable of doing the work of cells?
no; cells are to small to maintain significant internal temperature differences.
What type of reaction do cells rely on for energy?
chemical reaction
Second Law of Thermodynamics states that
disorder in the universe, aka entropy is continuously increasing in the universe as energy changes occur … so disorder is more likely than order.
concerns the transformation of potential energy into heat, or random molecular motion during any energy transaction.
second law of thermodynamics
Entropy
a measure of the randomness or disorder of a system, a measure of how much energy in a system has become dispersed that is no longer available to do work. 2) continuously increasing
What form of energy increases atomic motion, thus making it easier for atoms to pull apart.
heat energy
DOES chemial bonding reduce or increase disorder?
….Does heat reduduce or increase chemical bonding?
Chemical bonding reduces disorder
…..Heat increases chemical bonding
Free energy
the amount of energy actually available to break and subsequently form other chemical bonds, is called
The energy available to do work in any system
free energy
Free energy is denoted by what symbol?
G
- In a chemical reaction, the energy contained in the chemical bonds of the molecule,
- symbolized as H;
- in a cellular reaction, the f_ree energy_ is equal to the enthalpy of the reactant molecules in the reaction
enthalpy
S is the symbol for what?
What does T represent?
- S is the symbol for entropy
- T is the absolute temperature (k= C + 273)
What is free energy (G) equal too?
G= H - TS
- If the products have more free energy than the reactants, ΔG is
- such reactions require an input of energy, thus, are they(spontaneous/ not spontaeous)?
- What is the name of this reaction?
- positive
- not spontaneous - this can be because either the bond energy (H) is higher*, or the *disorder (S) in the system is lower
- Endergonic reaction
Describes a chemical reaction in which the products contain more energy than the reactants, so that free energy must be put into the reaction from an outside source to allow it to proceed.
endergonic reaction
- Products of the reaction contain more energy than the reactants, and the extra energy must be supplied for the reaction to proceed. What is the name the reaction?
- Products contain less energy than the reactants, and the excess energy is released. What is the name of the reaction?
- endergonic reaction
- exergonic reaction
- If the products have less free energy than the reactants, ΔG is
- Will the reaction proceed spontaneously or not spoontaneously?
- This reaction releases excess free energy as what?
- What is the name of this reaction?
- Negative
- Spontaneously - the negative ΔG can be because the bond energy (H) is lower, or the disorder (S) is higher, or both.
- releases excess free energy as heat
- Exergonic reaction
Describes a chemical reaction in which the products contain less free energy thatn the reactants, so that free energy is released in the reaction.
Exergonic reaction
Chemical reactions are reversible.
- A reaction that is exergonic in the foward direction will be __________ in the reverse reaction.
- enedergonic
- An exergonic reaction has an equilibrium favoring products or reactants?
- An endergonic reaction has an equilibrium favoring products or reactants?
- Products
- Reactants
Spontaneous chemical reactions require what type of energy?
activation energy
The extra energy needed to destabilize existing chemical bonds and initiate a chemical reaction is called
Activation energy
Activation Energy
The energy that must be processed by a molecule in order for it to undergo a specififc chemical reaction.
Why don’t exergonic reactions proceed rapidly?
Because activation energy must be supplied to destabilize existing chemical bonds.
- Catalysts accelerate particular reactions by
- Do catalysts alter the free energy change produced by the reaction?
- lowering the amount of activation energy required to initiate the reaction.
- NO
- The rate of an exergonic reaction depends on what? For the reaction to begin
- Activation energy
Reactions with larger activation energies tend to proceed much faster or more slowly?
- more slowly
Give two ways to increase the rate of reactions
- increase energy of reacting molecules (ex: heating up reactants)
- lower activation energy (ex: use a catalyst)
- The process of influencing chemical bonds in a way that lowers activation energy needed to initiate a reaction is called
- Substances that accomplish this are known as
- Catalysis
- Catalysts
Catalysis
The process by which chemical subunits of larger organic molecules are held and positioned by enezymes that stress their chemical bonds, leading to the disassembly of the larger molecule into its subunits, often with the release of energy.
- What stage in a reaction do catalysts affect?
- The energy needed to reach this stage is called?
- Catalysts stabalize this stage, thus a result of?
- Intermediate stage (transition state)
- Activation energy
- lowering activation energy
- Can catalysts violate the basic laws of thermodynamics?
- Can catalysts make an endergonic reaction proceed sponaneously?
- By reducing activation energy, how does a catalyst affect the foward and reverse reaction?
- Does a catalyst alter the proportion of reactant ultimately converted into product?
- What can catalysts do for a reaction?
- In living systems, what acts as a catalyst?
- no
- no
- accelerates both by exactly the same amount.
- no
- What catalysts can do is make a reaction proceed much faster.
- In living systems, enzymes act as catalysts.
The direction in which a chemical reaction proceeds is determined solely by
the difference in free energy between reactants and products.
The chief “currency” all cells use for their energy transactions is the nucleotide
ATP
Power almost every energy requiring process in cells
ATP
ATP is composed of three smaller components. What are they?
- 5- Carbon sugar, ribose
- Adenine - an organic molecule composed of two carbon nitrogen rings.
- Chain of 3 phosphates
The key to how ATP stores energy lies in which of its 3 components?
The key to how ATP stores energy lies in its triphosphate group.
- Phosphate groups storngly repel eachother. Are they highly positively or negatively charged?
- Are the covalent bonds joining the phosphates stable or unstable?
- The (stable/unstable) bonds holding the phosphates together in the ATP molecule have a low ________ energy?
- The (stable/unstable) bonds holding the phosphates together in the ATP molecule are easily broken by ________?
- Highly negatively charged
- Unstable
- Low activation energy
- Hydrolysis
Hydrolysis of ATP releases energy that can be used to perform work. Does Hydrolysis of ATP have a positive or negative ΔG?
Hydrolysis of ATP has a negative ΔG
In most reactions involving ATP, only the outermost high-energy phosphate bond is hydrolyzed, cleaving off the phosphate group on the end. When this happens, ATP becomes
Adenosine diphosphate (ADP) + Inorganic phosphate (Pi)
A molecule that is not a part of an organic molecule; groups are added and removed in the formation and breakdown of ATP and in many other cellular reactions.
Inorganic phosphate (Pi)
What do cells use to drive endergonic processes.
ATP (hydrolysis)
- That is, energy released by the hydrolysis of ATP can supply the energy needed by the endergonic reaction.
- Because most endergonic reactions in cells require less energy than is released by ATP hydrolysis, ATP supplies most of the energy a cell needs.
- Why don’t endergonic reatcions proceed spontaneously?
- ΔG for an endergonic reaction is positive or negative?
- Because their products possess more free energy than their reactants
- positive
- What makes ATP an effective energy donor?
- Is ATP an effective long term energy storage molecule?
- Instability (unstable) of its phosphate bonds
- No, ATP is a poor long term energy storage molecule because of its unstable phosphate bonds. (Fats & Carbs serve that function better)
- Is the synthesis of ATP from ADP + Pi endergonic or exergonic?
- Do cells use endergonic or exergonic reacions to provide energy (power) to synthesize ATP from ADP + Pi?
- Cell then use the hydrolysis of ATP to power (drive) endergonic or exergonic processes?
- Is the hydrolysis of ATP to ADP + Pi endergonic or exergonic?
- Endergonic
- Exergonic reactions
- Endergonic
- Exergonic
- Cells typically have unlimited supply of ATP at any given time, and they continually produce more from ADP and Pi. Is this statement true or false?
-
False.
* Cells typically have only a few seconds’ supply of ATP at any given time, and they continually produce more from ADP and Pi.
- The chemical reactions within living organisms are regulated by controlling the points at which ______ (hint: process) takes place.
- The catalysts in living systems are known as what?
- catalysis
- Enzymes
Highly specific catalysts found in living systems are known as?
enzymes
The unique three-dimensional shape of an enzyme enables it to stabilize a temporary association between
substrates
- The foundation to which an organism is attached.
- A molecule on which an enzyme acts.
- The molecules that will undergo the reaction.
- What is being described?
Substrates
- By bringing two substrates together in the correct orientation or by stressing particular chemical bonds of a substrate; an enzyme will do what?
- Lower the activation energy required for new bonds to form.
- The reaction thus proceeds much more quickly than it would without the enzyme.
- The enzyme itself is not changed or consumed in the reaction.
- Only a small amount of an enzyme is needed, and it can be used over and over.
- When an enzyme lowers activation energy required to form new bonds;
- Does the reaction proceed slower or faster?
- Is the enzyme changed, consumed, both or neither in the reaction?
- Is a large or small amount of the enzyme needed for the reaction?
- How often can the enzyme be used in the reaction?
- Faster
- Neither
- Small amount
- It can be used over and over again
Most enzymes are globular proteins with one or more pockets or clefts, called ________?
Active Sites
The region of an enzyme surface to which a specific set of substrates binds, lowering the activation energy required for a particular chemical reaction and so facilitating it.
Active Site
Substrates bind to enzymes at the active sites. Thus, forming what?
enzyme-substrate complex
The complex formed when an enzyme binds with its substrate. This complex often has an altered configuration compared with the nonbound enzyme.
enzyme-substrate complex
If catalysis is to occur within a complex, how must the substrate molecule fit into the active site?
a substrate molecule must fit precisely into an active site for catalysis to occur within the complex
When an enzyme molecule fits perfectly into an active site, the what happens to the amino acid side groups of the enzyme?
- The amino acid side groups of the enzyme end up very close to certain bonds of the substrate.
- These side groups interact chemically with the substrate, usually stressing or distorting a particular bond and consequently lowering the activation energy needed to break the bond. After the bonds of the substrates are broken, or new bonds are formed, the substrates have been converted to products.
- These products then dissociate from the enzyme, leaving the enzyme ready to bind its next substrate and begin the cycle again.
- Are proteins rigid?
- No
The bindinding of a substartate induces the enzyme to adjust its shape slightly, leading to a better induced fit between the enzyme and substrate. (T/F)
True
