Chapter 8: An Introduction to Metabolism

Question 1

Metabolic Pathway

Answer 1

where a specific molecule is altered in a series of defined steps, resulting in a certain product, each step catalyzed by an enzyme

Question 2

Catabolic Pathway

Answer 2

metabolic pathway that releases energy by breaking down complex molecules into simpler compounds

Question 3

Anabolic Pathways

Answer 3

consume energy to build complex molecules from simple ones

Question 4

Bioenergetics

Answer 4

study of how energy flows through living organisms

Question 5

Energy

Answer 5

capacity to cause change

Question 6

Thermal Energy

Answer 6

kinetic energy associated with the random movement of atoms or molecules

Question 7

Kinetic Energy

Answer 7

relative motion of an object

Question 8

Heat

Answer 8

thermal energy in transfer from one object to another

Question 9

Potential Energy

Answer 9

an object not presently moving but possessing the possibility of movement

Question 9

Second Law of Thermodynamics

Answer 9

every energy transfer or transformation increases the univers’ entropy or randomness

Question 10

Chemical Energy

Answer 10

potential energy available for release in a chemical reaction

Question 11

Thermodynamics

Answer 11

study of energy transformations that occurr in a collection of matter

Question 11

First Law of Thermodynamics

Answer 11

energy can be transformed or transferred but it can not be created or destroyed

Question 12

Spontaneous Process

Answer 12

if a given process, by itself, leads to an increase in entropy, the process can proceed without requiring an input of energy (spontaneous meaning energetically favorable)

Question 13

Entropy

Answer 13

a quantity used to measure molecular disorder, also known as randomness

Question 14

Free Energy

Answer 14

the portion of a systems energy that can perform work when temperature and pressure are uniform throughout the system

Question 15

Exergonic Reaction

Answer 15

energy outward reaction, releases free energy, “downhill”

Question 15

Endergonic Reaction

Answer 15

energy inward, stores free energy, “uphill”

Question 16

Energy Coupling

Answer 16

key way cells manage their energy resources, use of an exergonic reaction process to drive an endergonic one

Question 16

3 Main Kinds of Cell Work

Answer 16

chemical, transport, and mechanical

Question 17

Chemical Work

Answer 17

the pushing of endergonic reactions that would not occur spontaneously

Question 17

Transport Work

Answer 17

the pumping of substances across membranes against the direction of spontaneous movement

Question 18

Mechanical Work

Answer 18

contraction of muscle cells and the movement of chromosomes during cellular respiration

Question 19

ATP

Answer 19

adenosine triphosphate, main energy source in the body, able to be broken down by hydrolysis to form ADP and P

Question 20

Phosphorylated Intermediate

Answer 20

recipient molecule with the phosphate group covalently bonded to it, this formation is key to coupling exergonic and endergonic reactions, less stable, more free energy than unphosphorylated molecule

Question 21

Phosphorylation

Answer 21

the transfer of a phosphate group from ATP to some other molecule

Question 22

Regeneration of ATP

Answer 22

ATP is a renewable resource, regenerates by the addition of a phosphate to ADP, free energy needed to phosphorylate ADP comes from exergonic breakdown reactions (catabolism)

Question 22

Activation Energy

Answer 22

energy required to contort the reactant molecules so that the bonds can break, amount of energy needed to push reactants to the top of an energy hill/barrier, often supplied by thermal energy

Question 23

ATP Cycle

Answer 23

shuttling of inorganic phosphates and energy across the membrane, couples the cells energy-yielding (exergonic) processes to the energy consuming (endergonic) processes

Question 24

Catalysis

Answer 24

process in which a catalyst selectively speeds up a reaction without being consumed itself

Question 25

Enzymes Substrate

Answer 25

the reactant an enzyme acts on

Question 26

Induced Fit

Answer 26

tightening of an active site once binded to the substrate, like a two-handed handshake, brings chemical groups of active sites together to enhance catalyzation abilities

Question 26

Active Site

Answer 26

restricted region of the enzyme molecule that binds to the substrate, pocket/groove on the surface of the enzyme where catalysis occurs, formed by only a few of the enzymes amino acids

Question 27

Mechanisms to Lower Activation Energy and Speed Up Reactions

Answer 27

-template providing
-stretching and twisting
-fit environment
-amino acid bonding

Question 28

Effects of Temp and pH on enzymes

Answer 28

too high of temperatures can denature an enzyme, too acidic or basic of a pH can denature an enzyme, too low of temperatures slow down enzyme function to a point of not working but not to denaturation

Question 29

Noncompetitive Inhibitors

Answer 29

do not directly compete with substrates to bind at the active site, impede reactions by binding to another part of the enzyme thus changing the molecules shape to the extent that the binding site is less effective in catalyzation

Question 29

Optimal Conditions

Answer 29

favor the most active shape of an enzyme, up to a point, enzymes react increasingly with rising temp because substrates collide with active sites more frequently, each enzyme has a different and specific optimal temperature

Question 29

Competitive Inhibitors

Answer 29

reduces productivity of enzymes by blocking substrates from attaching to active sites, can be overcome by producing more substrates so that more active sites become available

Question 30

Cofactors

Answer 30

either bound loosely or tightly to an enzyme, nonprotein helper for catalytic activity, for chemical processes like electron transfer that cant be carried out by amino acids in proteins

Question 30

Coenzyme

Answer 30

name for organic cofactors, vitamins act as coenzymes or raw materials from which coenzymes are made up of

Question 31

Feedback Inhibition

Answer 31

mode of metabolic control in which a metabolic pathway is halted by the inhibitory binding of its end product to an enzyme that acts early in the pathway

Question 31

Allosteric Regulation

Answer 31

a protein’s function at one site is affected by the binding of a regulatory molecule on a separate site, resulting in either inhibition or stimulation of an enzyme, entire complex oscillates between active and inactive, activators stabilize shape, inhibitors stabilize inactive enzyme form

Question 31

Multienzyme Complex

Answer 31

team of enzymes for several steps of a metabolic pathway assembled into one space, not just floating around the cell

Question 32

Cooperativity

Answer 32

substrate molecules bind to one active site in a multisubunit enzyme, triggering a shape change in all subunits, thereby increasing catalytic activity at another site, amplifies the response of enzymes to substrates

Question 33

Enzyme Substrate Complex

Answer 33

formed when an enzyme binds to its substrate

Question 33

Stretching and Twisting

Answer 33

the enzyme stretches the substrate molecules until their bonds bend and break, thus bringing them to the transition state. activation energy is proportional to the difficulty of bond breaking, distorting the substrate helps substrate make the reactions occur faster and with less free energy absorbed

Question 34

Template Providing

Answer 34

with two or more reactants in a reaction, the active site provides a template on which the substrates can join in the proper order for a reaction to occur

Question 35

Fit Environment

Answer 35

the active site provides an environment conducive to certain reactions, more so than the solution itself without the enzyme

Question 36

Amino Acid Bonding

Answer 36

amino acids will sometimes briefly bond to substrates and the side chain of the amino acid, subsequent steps restore the chains to the original state and the active site is good as new for more reactions