Lecture 10

Question 1

how are polymers synthesized

Answer 1

dehydration

Question 2

how are polymers broken down

Answer 2

hydration

Question 3

what is a catabolic pathway

Answer 3

energy is released by the breakdown of complex molecules to simpler compounds; overall ΔG is negative

Question 4

what is an anabolic pathway

Answer 4

energy is used to build complicated molecules from simpler ones; overall ΔG is positive

Question 5

what is kinetic energy

Answer 5

the energy of an object in motion

Question 6

what is potential energy

Answer 6

stored energy

Question 7

what is thermal energy

Answer 7

kinetic energy associated with random movement of atoms or molecules

Question 8

what is chemical energy

Answer 8

is potential energy availablefor release in a chemical reaction

Question 9

what are the four forms of energy

Answer 9

light, electricity, motion, heat

Question 10

what is the first law of thermodynamics

Answer 10

Energy can be changed from one form to another, but it cannot be created or destroyed

Question 11

what is the second law of thermodynamics

Answer 11

Every energy transfer or transformation increases the disorder (entropy) of the universe

Question 12

what causes a reaction to be spontaneous

Answer 12

the products are less ordered than the reactants; the products have less energy than the reactants

Question 13

what does it mean for a reaction to be spontaneous

Answer 13

a process that can occur without an input of energy; must increase the entropy of the universe

Question 14

how can a non-sponatanous reaction occur

Answer 14

can only occur if energy is added to the system

Question 15

what does it mean when an reaction is exothermic

Answer 15

reactions release energy; the products have less potential energy than the reactants; spontaneous; more stable

Question 16

what does it mean when an reaction is endothermic

Answer 16

reactions absorb energy; the products have more potential energy than the reactants; not spontaneous; less stable

Question 17

how does a reaction end with a negative delta-G, the system must…

Answer 17

give up enthalpy, give up order, or both

Question 18

what is free-energy

Answer 18

energy available to do work

Question 19

what is ΔG

Answer 19

is a measure of a system’s instability – its tendency to change to a more stable state

Question 20

what type of systems are living organisms

Answer 20

open systems

Question 21

what is the ultimate source of energy for most organisms

Answer 21

the sun

Question 22

a cell does what three main kinds of work

Answer 22

chemical, transport, and mechanical

Question 23

why is ATP important

Answer 23

temporarily stores chemical potential energy that drives most cellular work

Question 24

what is phosphorylation

Answer 24

Terminal phosphate group is transferred to a reactant molecule involved in an endergonic reaction

Question 25

what are catalysts

Answer 25

chemical agent that speeds up a reaction without being consumed by the reaction

Question 26

what is activation energy

Answer 26

The initial energy needed to start a chemical reaction is called the free energy of activation

Question 27

how are enzymes beneficial to reactions

Answer 27

enzymes reduce activation energy and speed up metabolic reactions

Question 28

what is the active site

Answer 28

The substrate interacts with a small pocket or groove in the enzyme molecule

Question 29

how do enzymes lower activation energy

Answer 29

Bringing the reacting molecules together; Changing the shape of the substrate molecules; Providing a microenvironment that promotes catalysis; Participating directly in the chemical reaction

Question 30

what determines enzyme activity

Answer 30

initial substrate concentration, environmental conditions, cofactors, enzyme inhibitors

Question 31

what are cofactors

Answer 31

non-protein helpers

Question 32

what are enzyme inhibitors

Answer 32

competitive and noncompetitive

Question 33

what are competitive inhibitors

Answer 33

they bind to the active site of an enzyme, competing with the substrate- can be overcome by increase [substrate]

Question 34

what are noncompetitive inhibitors

Answer 34

they bind to another part of an enzyme, causing the enzyme to change shape and making the active site less effective

Question 35

what is allosteric regulation

Answer 35

Enzyme’s function at one site is affected by the binding of a regulatory molecule at another site; activation and inhibitors

Question 36

what is feedback inhibition

Answer 36

End product switches off the metabolic pathway

Question 37

what is allosteric activation

Answer 37

enzyme binds allosteric activators; binding activator converts enzyme to high-affinity state; in high-affinity state, enzyme binds substrate

Question 38

what is allosteric inhibition

Answer 38

enzyme binds allosteric inhibitor, binding inhibitor converts enzyme to low-affinity state; substrate is released

Question 39

why is feedback inhibition important

Answer 39

prevents a cell from wasting chemical resources