chapter 8: energy (test 4)

Question 1

• 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

Answer 1

energy

Metabolism

Question 2

A ___ begins with a specific molecule which is converted to a product

Each step is catalyzed by a specific ___

Answer 2

metabolic pathway

enzyme

Question 3

___ release energy by breaking down complex molecules into compounds

–Ex Cellular respiration,

___ consumes energy to build complex molecules from smaller compounds

–Ex Photosynthesis

Answer 3

Catabolic pathways

Anabolic pathways

Question 4

___ is the study of how organisms manage their energy resources

Answer 4

Bioenergetics

Question 5

•___ is energy associated with motion

–Heat (thermal energy) is kinetic energy associated with random movement of atoms or molecules

Answer 5

Kinetic energy

Question 6

•___ is energy that matter possesses because of its location or structure

–Chemical energy is potential energy stored in chemical bonds.

Answer 6

Potential energy

Question 7

•___ is the study of energy transformations

Answer 7

Thermodynamics

Question 8

• 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

Answer 8

closed system

open system

Question 9

•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

Answer 9

first

constant

Question 10

• 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

Answer 10

Second

Question 11

• 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

Answer 11

can do work

Question 12

• 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”)!

Answer 12

exergonic reaction

Question 13

• 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”)

Answer 13

endergonic reaction

Question 14

___ powers cellular work by coupling exergonic reactions to endergonic reactions

Answer 14

ATP

Question 15

•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

Answer 15

Chemical

Transport

Mechanical

Question 16

•Cellular work is powered by ___

Answer 16

ATP hydrolysis.

Question 17

• 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.

•

Question 18

•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

•

Answer 18

enzyme

Question 19

• 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

Answer 19

free energy of activation

Question 20

• 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

•

Answer 20

substrate

enzyme-substrate complex

active site

Question 21

• Each enzyme has an optimal temperature in which it can function
• Each enzyme has an optimal pH in which it can function

Question 22

___ are non protein enzyme helpers

–Inorganic cofactors (ex metal in ionic form)

–Organic cofactor also called coenzymes (ex vitamins)

Answer 22

Cofactors

Question 23

• ___ 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

Answer 23

Competitive inhibitors

Noncompetitive inhibitors

Question 24

• 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

Answer 24

feedback inhibition