chapter 8: energy (test 4) Flashcards
- The living cell is a miniature chemical factory where thousands of reactions occur
- The cell extracts ___ and applies energy to perform work
- ___ is the totality of an organism’s chemical reactions
energy
Metabolism
A ___ begins with a specific molecule which is converted to a product
Each step is catalyzed by a specific ___
metabolic pathway
enzyme
___ release energy by breaking down complex molecules into compounds
–Ex Cellular respiration,
___ consumes energy to build complex molecules from smaller compounds
–Ex Photosynthesis
Catabolic pathways
Anabolic pathways
___ is the study of how organisms manage their energy resources
Bioenergetics
•___ is energy associated with motion
–Heat (thermal energy) is kinetic energy associated with random movement of atoms or molecules
Kinetic energy
•___ is energy that matter possesses because of its location or structure
–Chemical energy is potential energy stored in chemical bonds.
Potential energy
•___ is the study of energy transformations
Thermodynamics
- A ___, such as that approximated by liquid in a thermos, is isolated from its surroundings
- In an ___, energy and matter can be transferred between the system and its surroundings
- Organisms are open systems
closed system
open system
•The ___ law of thermodynamics states that the energy of the universe is ___:
– Energy can be transferred and transformed, but it cannot be created or destroyed
first
constant
- During every energy transfer or transformation, some energy is unusable, and is often converted to heat
- According to the ___ law of thermodynamics:
– Every energy transfer or transformation increases the entropy (disorder) of the universe
Second
- A living system’s free energy (G) is energy that ___ when temperature and pressure are uniform, as in a living cell
- Only processes with a negative ∆G are spontaneous
- ∆G= G(final state) – G (initial state)
- Spontaneous processes can be harnessed to perform work
can do work
- The concept of free energy can be applied to the chemistry of life’s processes
- An ___ proceeds with a net release of free energy and is spontaneous.
- ∆G is NEGATIVE (<0, “less than 0”)!
exergonic reaction
- The concept of free energy can be applied to the chemistry of life’s processes
- An ___ absorbs free energy from its surroundings and is not spontaneous.
- ∆G=Positive (>0, “greater than 0”)
endergonic reaction
___ powers cellular work by coupling exergonic reactions to endergonic reactions
ATP
•A cell does three main kinds of work:
– ___
– ___
– ___
- To do work, cells manage energy resources by energy coupling, the use of an exergonic process to drive an endergonic one
- Most energy coupling in cells is mediated by ATP
Chemical
Transport
Mechanical
•Cellular work is powered by ___
ATP hydrolysis.
- ATP is a renewable resource that is regenerated by addition of a phosphate group to adenosine diphosphate (ADP)
- The energy to make ATP from ADP and P requires energy (∆G = +7.3 kcal/mol), so this reaction is endergonic
- Catabolic (exergonic) pathways like cellular respiration provide the energy for endergonic regeneration of ATP.
•
•An ___ is a protein that acts as a catalyst - a chemical agent that speeds up a chemical reaction without being used up in the reaction
•
enzyme
- Every chemical reaction between molecules involves bond breaking and bond forming
- The initial energy needed to start a chemical reaction is called the ___, or activation energy (EA)
- Activation energy is often supplied in the form of heat from the surroundings
free energy of activation
- The reactant that an enzyme acts on is called the enzyme’s ___
- The enzyme binds to its substrate, forming an ___
- The reaction catalyzed by each enzyme is very specific
- The ___ is the region on the enzyme where the substrate binds
•
substrate
enzyme-substrate complex
active site
- Each enzyme has an optimal temperature in which it can function
- Each enzyme has an optimal pH in which it can function
___ are non protein enzyme helpers
–Inorganic cofactors (ex metal in ionic form)
–Organic cofactor also called coenzymes (ex vitamins)
Cofactors
- ___ bind to the active site of an enzyme, competing with the substrate
- ___ bind to another part of an enzyme, causing the enzyme to change shape and making the active site less effective
Examples of inhibitors include toxins, poisons, pesticides, and antibiotics
Competitive inhibitors
Noncompetitive inhibitors
- In ___, the end product of a metabolic pathway shuts down the pathway
- Feedback inhibition prevents a cell from wasting chemical resources by synthesizing more product than is needed
feedback inhibition
