Chapter 3: Energy,catalysis & B

Front 1

What do cells use enrgy for?

Back 1

to create and maintain order

Front 2

In order to to create and maintain order cells must continously carry out what?

Back 2

metabolism (chemical reactions)

Front 3

In order to carry out metabolism what do cells require?

Back 3

sources of matter and energy

Front 4

What declares that cells need energy input to create and maintain order?

Back 4

Second law of thermodynamics

Front 5

Second law of thermodynamics

Back 5

systems will change spontaneously toward those arrangments that have the greatest probability (disorder).

organization requires enrgy input

Front 6

Movement toward disorder is what type of process?

Back 6

spontaneous.

Front 7

Biological order is made possible by the release of what from cells?

Back 7

heat energy

Front 8

What is heat?

Back 8

Heat (random jostiling of atoms) is the most disorganized form of nergy.

Front 9

What must releae of heat be tightly coupled with ?

Back 9

generation of order.

Front 10

Cells use energy to do?

Back 10

Work

Front 11

synthetic work

Back 11

making new molecules

Front 12

mechanical work

Back 12

movement of organelles, chormosomes, cells, contraction of muscles.

Front 13

concentration work

Back 13

moving substances from regions of low concentration to high concentration

Front 14

electrical work

Back 14

moving protons from regions of low concentration to high concentration

Front 15

Where do living orgnsims get their energy?

Back 15

Almost all living things rely on the radiant energy of sunlight to sustain life

Front 16

What is enrgy from sunlight transformed into duirng photosynthesis?

Back 16

transformed inot chemical bond energy

electromagnetic energy (light)-->
high energy electron--> chemical bond energy

Front 17

why is heat generated in the process of photosynthesis?

Back 17

---

Front 18

What two processes are complementary? How?

Back 18

photosynthesis and respiration

1. photosynthetic cells make organic molecules using energy from the sun,

CO2+H2O-->O2+sugars

2. while all cells obtain energy by oxidation of organic molecules during resiration

sugar+O2-->H2O+Co2

Front 19

What cycles continously thorught he biosphere?

Back 19

carbon atoms

Front 20

Carbon is ____ during photosynthsis and then ____ during respiration or when fossil fuels are burned

Back 20

reduced
oxidized

Front 21

What are the key chemical reaction of living cells?

Back 21

Redox reaction (reduction/oxidation)

Front 22

Oxidation

Back 22

literally: addition of oxygen
generally: transfer of electrons from an atom

ex. Fe^2+ is oxided to Fe^3+

Front 23

Reduction

Back 23

addition of electrons to an atom

the atom become reduced in positive charge

Ex. Cl reduced to Cl- ion

Front 24

Oxidation and reduction reactions always occur_____

Back 24

Simultaneously (electrons are consrved)

Front 25

The terms oxidation and reduction apply even when ther is only a ____ ___ of electron betwn atoms linked by _____ bond.

Back 25

partial shift
covalent (polar)

Front 26

Oxidation and reduction can involve a shift in the____ of electrons.

Back 26

balance

Front 27

Hydrogenation

Back 27

a carbon atom becomes more reduced with the additon of hydrogen atoms

Front 28

Dehydrogenation

Back 28

reactions that are similar to oxidations

Front 29

Cells use this to catalyze oxidation of organic moleuels in small steps. What does this allow to be extracted?

Back 29

enzymes
useful energy extracted

Front 30

Enzymes

Back 30

catalyse the synthesis of large, complex and energy rich molecules as well as orgnaic molecules

Front 31

What of molecules affects whether a chemical reaction can proceed?

Back 31

relative free energy

Front 32

Cell drive energetically ___ reactions by coupling them to energetically ____ones

Back 32

unfavorable
favorable

Front 33

Metabolism

Back 33

food molecules go down catabolic pathway and become many building blocks for biosyntheis (heat is lost +useful forms of energy) the builiding blocks go thorugh anaboic pathway + use the useful foms of energy lost in catabolic patway to make many molecules that from the cell

Front 34

Catabolism

Back 34

in some reactions molecules are broken down

Front 35

Anabolism

Back 35

in some reactions moleucles are synthesized

Front 36

catalysis

Back 36

chemical reactions require this, allwos cells to control their metabolism

Front 37

Even energetically favorable reactions require this to get them started?

Back 37

activation energy

Front 38

Enzyme ---- activation energy

Back 38

lowers

Front 39

Lowering the activation energy ---- the probability that the reaction will occur

Back 39

increases

Front 40

This can lower activation enrgy barries in general but ---- slectively lower the activation erergy barriers fora specific reaction pathway

Back 40

heat
enzymes

Front 41

What do enzyme convert whil remaining unchanged themselves?

Back 41

substrates to products.

Front 42

What pathway is energetically unfavorable?

Back 42

anabolic pathway

Front 43

Free energy (G)

Back 43

is the amount of energy available to do work.

Front 44

What determines wheter G can occur?

Back 44

The free energy for a reaction (^G)

Front 45

Energentically favorable reactions

Back 45

X-->Y

G of Y is> then G of X therefore
^G<0

disorder of the universe increased during the reaction

reaction can occur spontaneously

Front 46

Energetically unfavorable reaction

Back 46

X-->Y

G of Y is< then G of X therefore
^G>0
universe becomes more ordered during the reaction

reaction can occur only if it is coupled to a second energeticaly favorable reaction

Front 47

What can reaction coupling drive?

Back 47

an engergtically unfavorable reaction

Front 48

What do cells use reaction coupling for?

Back 48

To drive biosynthetic reactions.

Front 49

What does the concentration of the reactants influence?

Back 49

the free energy change and a reactions direction

Front 50

Delta G depends not only on the energy stored in a moleulce but on the ---- of thmolecules in the reaction mixture

Back 50

concentration

Front 51

Effects of concnetrion on a reversible chemical reaction

reversible means ^G <~30 kcal/mol

Back 51

Y<=> X

if [Y] > [X] then reaction Y--->X
if [Y] < [X] then reaction Y<---X

Front 52

What makes it possible to compare the energetics of different reactions?

Back 52

The standard free energy change (^Go)

Front 53

Def of ^Go

Back 53

the free energy change under standard conditons of 37oC temperature and 1 mole/liter concnetration of reactants.

Y<=>X

^G=^Go + RT ln [X]/[Y]

[X] and [Y] are in moles/liter

RT=0.616

Front 54

At equilibrium what equals 0

Back 54

^G

Front 55

What is directly proprotional to ^Go ?

Back 55

Equilibrium constant (K)

K=[X]/[Y]

x=product
y=reactants

Front 56

In complex reactions, K depends on the concnetration of ---- and ----

Back 56

all reactants and products

A=B<=>AB

K=[AB]/[A][B]

Front 57

K is also the measure of ---- and ---- of ---- interactions between two molecules.

Back 57

strenght and specificty of noncovalent

Front 58

Dissociation rate

Back 58

AB-->A+B
dissociation rate= dissociation rate constant x [AB]

dissociationrate=koff[AB]

Front 59

Types of noncovalent interactions where dissociation rate can be used?

Back 59

1.binding of regulatory proteins to DNA
2.Binding of substates to enzymes
3. binding of proeteins to each other

Front 60

Association rate

Back 60

A+B--->AB
association rate= association rate constant x [A] x [B]

assocition rate = kon [A][B]

Front 61

When does equilibrium constant, K, becomes larger?

Back 61

binding energy increases

Front 62

When does association rate= dissociation rate?

Back 62

At equilibrium

[AB]/[A][B]= kon/koff = K = equilibirum constant

Front 63

What does small changes in the number of weak obonds have a drastic effect on?

Back 63

bidning interactions.

Front 64

How can enzymes catalyse energetically unfavorable reactions?

Back 64

1. They can sequentially couple a set of reactions. For sequetial reaction, the changes in free energy are additive

2. It can be driven by a second reaction that acts as a chemical siphone

Front 65

Enzymes can also couple reactions together by

Back 65

making making activated carrier molecules that can move energy form one reaction site to another

Front 66

A random walk?

Back 66

small molecules (typical substrate for enzymes) traverse rapidly though cells in random fashion

1/5 second for a small moleucle to diffuse 10 um

Front 67

Molecules that cannot move around?

Back 67

1.Some proteins are tethered to interacting proteins at specific locations

2. Macromolecules in general are too crowded to move around

Front 68

For a relelaively abundant substrate (0.5 mM) what will collide with the substrate and how many times?

Back 68

one enzyme molecule active site.

collide 500,000 times each second.

Front 69

How is enzyme performance meausred?

Back 69

By Vmax and KM

Front 70

An enzyme that tightlyy binds a substrate has a ----- Km

Back 70

---

Front 71

At Vmax all enzyme molecules are whata?

Back 71

Bound with subsrate (maximum rate at which subsrate molecules can be processed).

Front 72

Why is it hard to obsedrve Vmax and Km on a graph?

Back 72

becuse plots of velocity vs. substrate concnetraion yield a curve.

Front 73

What can enzymes no change about reactions?

Back 73

the equilibrium point.
They spped up the forward and reverse reactions by the same factor

Front 74

Cells drive the unfavorable reactions of biosynthesis by using ---- ----- to couple those reaction to the ---- of food

Back 74

activated carriers
oxidation

Front 75

What can activated carriers do to energy needed for metaboism?

Back 75

Store and transfer

Front 76

Activated carriers are found in what do reactions?

Back 76

Catabolism
anabolism

Front 77

Themost widely used, important and versatile activated carrier moleule in cells?

Back 77

ATP

Front 78

What part of ATP is readily transfered to other moleules.

Back 78

The terminal phospahte.
The phosphorylated moleucle is now 'activated'

ATP-->ADP reulsts in a -^Go

Front 79

The activated molecule can combine with what in a seond step to release what?

Back 79

Combine with another molecule to release inorganic phosphate

Front 80

What are important electron carriers?

Back 80

NADH and NADPH

Front 81

what do electron carries carry?

Back 81

high energy electrons and hydrogen atoms.

Front 82

What is carried by NADPH and why is it readily given up?

Back 82

Hydride ion (H-)
becuse the ring can achive a more stable arrangements of electrons without it.

Front 83

Example of a process NADPH is used in?

Back 83

Used in the fianl stage of a synthesis leading to chloslesterol

-bives up H and release NADP+ and cholesterol

Front 84

WHy are there two different electron carriers?

Back 84

Because 2 types of electron-transfer rections must be regulated independently.

Front 85

What reactions is NADPH used in?

Back 85

anabolic reactions

Front 86

What reactions are NADH used in

Back 86

Used as an intermediate in cataboic reations that genreate ATP thorugh the oxidation of food.

Front 87

In cells what are the concnetrion of NADPH and NADH compared to their precursors?

Back 87

[NAD+]>>>>> [NADH]
more oxidizing agent around

[NADPH]>>>>>[NADP]
more reducing agent around

Front 88

Activated carrier molecule, Acetyl , has a transferable group (high energy) attached to the nuclotide what is it

Back 88

acetyl grouop

Front 89

What is the activated carrier carboxylated biotin generated by?

Back 89

hydrolysis of ATP
-carboxyl group transferable

Front 90

What does the synthesis of biological polymers (polysacharide, nucleic acids, proetins) requires?

Back 90

energy imput form nucleoside triphosphate hydrolyssis

Front 91

What two things can ATP be hydrolysed into to drive reactions that need more than -13 kcal/mol

Back 91

AMP and pyrophosphate

Front 92

What are the two stop process that sysnthesis of a polynucleotide (DNA or RNA) requires?

Back 92

1. release of phyrophosphate
2. hydroylsis to inorgnic phosphate