Bio 1080 Chapter 8

Front 1

Metabolism

Back 1

sum of all chemical reactions occurring in an organism

Front 2

metabolic pathway

Back 2

begins with a specific molecule and ends with a product- each step catalyzed by a specific enzyme

Front 3

catabolic pathways

Back 3

release energy- breaking down complex molecules into simpler compounds, ei. cellular respiration, the breakdown of glucose

Front 4

anabolic pathways

Back 4

comsume energy to build complex molecules from simpler ones, ei. the synthesis of protein from amino acids

Front 5

energy

Back 5

the capacity to cause change- exits in various forms, some of which can perform work- can be converted from one form to another

Front 6

kinetic energy

Back 6

energy associated with motion

Front 7

heat (thermal energy)

Back 7

kinetic energy associated with random movement of atoms or molecules

Front 8

potential energy

Back 8

energy that matter possesses because of its location or structure

Front 9

chemical energy

Back 9

potential energy available for release in a chemical reaction

Front 10

origin of energy

Back 10

flows into the biological world from the sun, photosynthetic organisms capture it, and it is stored as potential energy in chemical bonds

Front 11

first law of thermodynamics

Back 11

energy cannot be created or destroyed, can only change from one form to another- during each conversion, some is lost as heat (unusable) but the total amount of energy in the universe remains constant

Front 12

second law of thermodynamics

Back 12

every energy transfer or transformation increases the entropy of the universe

Front 13

entropy

Back 13

disorder of the universe

Front 14

spontaneous processes

Back 14

occur without energy input, can happen quickly or slowly- increas the entropy of the universe

Front 15

free energy

Back 15

the energy available to do work, denoted by the symbol G

Front 16

enthalpy

Back 16

energy contained in a molecule's chemical bonds

Front 17

G = H - (TS)

Back 17

free energy = enthalpy - (temp x entropy)

Front 18

⌂G = ⌂Y - T⌂S

Back 18

equation representing changes in free energy

Front 19

⌂G is positive

Back 19

when products contain more free energy than reactants

Front 20

⌂G is negative

Back 20

when reactants contain more free energy than products

Front 21

endergonic reaction

Back 21

a reaction requiring an input of energy (not spontaneous) ⌂G is positive

Front 22

exergonic reaction

Back 22

a reaction that releases free energy (sponaneous) ⌂G is negative

Front 23

⌂G > 0

Back 23

products have more free energy than reactants, H (enthalpy) is higher or S is lower (entropy), not spontaneous- requires input of energy, endergonic

Front 24

⌂G < 0

Back 24

products have less free energy than reactants, H (enthalpy) is lower or S (entropy) is higher or both, spontaneous (though it may not be instantaneous), exergonic

Front 25

ATP powers...

Back 25

cellular work by coupling exergonic reactions to endergonic reactions

Front 26

cell does three main kinds of work

Back 26

chemical, transport, mechanical

Front 27

energy coupling

Back 27

the use of an exergonic process to drive an endergonic one, managing the cell's energy resources- a process mediated in cells by ATP most of the time

Front 28

ATP

Back 28

adenosine triphosphate, the cells energy shuttle- composed of a ribose (sugar), adenine (nitrogenous base) and three phosphate groups

Front 29

hydrolysis of ATP

Back 29

bonds between the phosphate groups of ATP's tail can be broken by hydrolysis, energy is released when the terminal P bond is broken, energy release comes from chemical change to state of lower free energy

Front 30

APT uses exergonic reaction to

Back 30

drive an endergonic reaction, overall the coupled reactions are exergonic

Front 31

phosphorylation

Back 31

the transferring of a phosphate group to some other molecule, such as the reactant- an ATP driven endergonic reaction

Front 32

phosphorylated intermediate

Back 32

recipient molecule during phosphorylation

Front 33

ADP + Pi ---> ADP

Back 33

the energy released from an exergonic reaction can be used to fuel the production of ATP

Front 34

activation energy

Back 34

extra energy needed to get a reaction started [destabilized existing chemical bonds- required even for exergonic reactions- often supplied by increasing the energy of the reacting molecules (heating)]

Front 35

calalysts

Back 35

substances that lower activation energy of a reaction- cannot violate laws of thermodynamics, cannot make endergonic reaction spontaneous, do not alter the proportion of reactant turned into product

Front 36

enzyme

Back 36

is a biological catalyst, most of which are proteins

Front 37

substrate

Back 37

the reactant that an enzyme acts on is called th enzyme's substrate

Front 38

enzyme-substrate complex

Back 38

when an enzyme is bonded to it's substrate

Front 39

active site

Back 39

region on the enzyme where the substrate binds

Front 40

induced fit

Back 40

brings chemical groups of the active site of a substrate into positions that enhance their ability to catalyze the reaction

Front 41

enzyme's rate of activity can be affected by

Back 41

gen. environmental factors such as pH and temp, chemicals that specifically influence the enzyme, amount of substrate available

Front 42

preferred pH values for enzymes

Back 42

pH between 6 and 8

Front 43

optimal temp for typical human enzyme

Back 43

37 degrees C

Front 44

optimal pH for pepsin (stomach enzyme)

Back 44

pH of 2

Front 45

cofactors and coenzymes

Back 45

additional molecules required by some enzymes for proper enzymatic activity

Front 46

cofactors

Back 46

usually metal ions, found in the active site participating in catalysis (Zn, Mn, Mo)

Front 47

Coenzymes

Back 47

organic molecule cofactors, includes vitamins (B6 and B12)

Front 48

enzyme inhibitor

Back 48

substance that binds to enzyme and decreases it's activity

Front 49

competitive inhibitors

Back 49

bind to the active site of an enzyme, competing with the substrate

Front 50

noncompetitive inhibitors

Back 50

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

Front 51

allosteric enzymes

Back 51

exist in either an active or inactive state and possess and allosteric site, where molecules other than the substrate bind- regulate activity of enzymes

Front 52

allosteric inhibitors

Back 52

bind to the alosteric site to inactivate the enzyme

Front 53

allosteric activators

Back 53

bind to the allosteric site to activate the enzyme

Front 54

biochemical pathways

Back 54

are a series of reactions in which the product of one reaction becomes the substrate for the next

Front 55

feedback inhibition

Back 55

the end product of a metabolic pathway shuts down the pathway-- prevents a cell from wasting chemical resources by synthesizing more product than is needed