Chapter 8 Flashcards
Metabolism
Totality of organism’s chemical reactions
Catabolic pathways
Energy released to break complex compounds to simple compounds
Anabolic pathways
Energy consumed to build complex compounds from simple compounds
Cellular respiration is a catabolic/anabolic pathway
Catabolic (spontaneous)
Energy
Capacity to cause change
Kinetic energy
Energy of motion
Thermal Energy
Kinetic energy associated with atom and molecule movements
Potential energy
Energy matter possesses because of location and structure
Chemical energy
Potential energy ready for release in chemical reactions
Complex molecules are high in which type of energy?
Chemical energy; lots of energy can be released when broken down in a catabolic pathway
Thermodynamics
Study of energy transformations
First Law of Thermodynamics
Energy cannot be created or destroyed; transferred
Second Law of Thermodynamics
Every energy transfer increases entropy of universe
Free Energy
Energy available for conversions
Why can’t all energy be available in free energy transfers?
Some energy is lost as heat
Spontaneous processes increase/decrease free energy
Decrease; move towards equilibrium in which there is no free energy available
The equation for free energy can be simplified to…
G = final state - initial
Equilibrium
State of maximum stability (free energy decreases as reactions reach this)
A negative free energy means….
Spontaneous/exergonic reaction. Free energy lost, stability increases, less likely to change
In spontaneous reactions, how does free energy and stability move?
- Free energy: decreases
- Stability: increases
Respiration is a _______ reaction, while photosynthesis is a ________ reaction (why?)
-Exergonic/spontaneous
-Endergonic
Photosynthesis requires an input of energy, in the form of sunlight
Diffusion is what type of reaction and why?
Exergonic because diffused molecules have lower free energy and are more stable
Exergonic reaction
Energy released to turn reactant to product
Endergonic reaction
Energy absorbed to turn reactant to product
What is the defining feature of life?
Metabolism is never at equilibrium, metabolic pathways fuel other reactions)
Cells does what kinds of work?
Chemical, transport, mechanical
Energy coupling
Use of exergonic process to drive an endergonic process
The bonds between phosphate groups in ATP can be broken by what?
Hydrolysis
The release of energy in ATP hydrolysis comes from what?
Chemical change to a state of lower free energy
The three types of cellular work are powered by what?
Hydrolysis of ATP
How does ATP drive endergonic reactions?
Through phosphorylation
Phosphorylation
Transfer of phosphate group to some other molecule, such as a reactant
The recipient molecule in phosphorylation is ______
phosphorylated
ATP is a renewable resource… how is it regenerated?
Addition of phosphate group to ADP
The energy to phosphorylate ADP comes from what?
Catabolic reactions in cell
The ATP formation from ADP and P is what type of reaction?
Endergonic; free energy must be spent
Catalyst
Chemical agent that speeds up reaction without being consumed
Enzyme
Catalytic protein
Activation Energy
Initial energy to start chemical reaction
(pertaining to activation energy) Reactant bonds break only when what? How do they get this?
- The molecules absorb enough to become unstable
- Absorb thermal energy
Activation energy is typically supplied by what?
Heat from surroundings
Enzymes do not affect this, but they ______
Don’t affect change in free energy, but hasten reactions that would eventually happen
Active site
Region on enzyme where substrate binds to
Induced fit
Enzyme changes to conform to substrate shape
How can the active site lower the activation energy barrier?
Orienting substrates correctly, straining substrate bonds, providing favorable microenvironment, covalently bonding to substrate
What can enzyme activity be affected by?
- pH and temperature
- Chemicals that influence enzyme
Cofactors
Nonprotein enzyme helpers
Coenzyme
Organic molecule cofactor
Competitive inhibitor
Inhibitor that binds to active site and competes with substrate
Noncompetitive inhibitor
Inhibitor that binds to another part of enzyme, changing shape to make active site less effective
Examples of inhibitors?
Toxins, poisons, pesticides, antibiotics
How does cell regulate metabolic pathways?
REgulating activity of enzymes
Allosteric regulation
Protein’s function at one site if affected by the binding of a different molcule at another site
How do allosteric regulators inhibit and stimulate enzyme activity?
- Inhibitor stabilizes inactive form of enzyme
- Activator stabilizes active form of enzyme
Feedback inhibition
End product of a metabolic pathway shuts down the pathway
Hydrolysis is what type of reaction?
Exergonic
Coupling involves transfer of energy with ______ to ______
Inorganic phosphate to a reactant
What would happen if organisms didnt have input of free enregy?
Entropy increases, death occurs
