Exam 2 - Lecture 9

Question 1

what three kinds of work must cells do?

Answer 1

• chemical work
• transport work
• mechanical work

Question 2

what is chemical work?

Answer 2

the synthesis of complex molecules

Question 3

what is transport work?

Answer 3

the take up of nutrients, elimination of wastes, and maintenance of ion balances

Question 4

what is mechanical work?

Answer 4

cell motility and movement of structures within the cell

Question 5

metabolism is a _______ of all the chemical reactions in a cell

Answer 5

total

Question 6

which of the following generates precursors for biosynthesis, catabolism or anabolism?

Answer 6

catabolism

Question 7

which of the following requires energy, catabolism or anabolism?

Answer 7

anabolism

Question 8

match the following:

a. catabolism
b. anabolism

1. synthesis of large, complex molecules
2. breakdown of large molecules into smaller, simpler ones

Answer 8

a2. catabolism: breakdown of large molecules into smaller, simpler ones

b1. anabolism: synthesis of large, complex molecules

Question 9

what is thermodynamics?

Answer 9

a science the analyzes the energy changes in a collection of matter called a system (example: a cell)

Question 10

what are the laws of thermodynamics?

Answer 10

• energy can neither be created nor destroyed
• entropy (the universe wants to constantly increase in entropy)

Question 11

what is entropy?

Answer 11

the amount of disorder/chaos in a system

Question 12

what is the free energy equation?

Answer 12

deltaG = deltaH - TdeltaS

(G = H - TS)

Question 13

what is the free energy equation used for?

Answer 13

it is used to indicate if a reaction will proceed spontaneously

Question 14

true or false: a positive deltaG mean a rxn is spontaneous.

Answer 14

false; a negative deltaG means a rxn is spontaneous

Question 15

is a negative deltaG indicate an exergonic or endergonic reaction?

Answer 15

exergonic = negative deltaG

Question 16

when is a reaction at equilibrium?

Answer 16

when the rate of the forward reaction matches that of the reverse reaction

Question 17

what is the Keq equation?

Answer 17

[C][D]/[A][B]

• concentration of products over reactants

Question 18

deltaG = -RT*log(Keq)

Answer 18

just know this i guess

Question 19

what is the energy currency of the cell?

Answer 19

adenosine 5’-triphosphate; ATP

Question 20

what is done to make endergonic reactions more favorable?

Answer 20

they are coupled with the breakdown of high energy ATP (an exergonic reaction)

Question 21

what is the deltaG of ATP hydrolysis?

Answer 21

-7.3 kcal/mol

Question 22

many metabolic processes involve oxidation-reduction reactions, which is the transfer of ___________

Answer 22

electrons

Question 23

when electrons move from a donor to an acceptor, this can result in energy _________ which can then be used to form ATP

Answer 23

release

Question 24

the more electrons a molecule has to donate, the more _________ _____ it is

Answer 24

energy rich

Question 25

an electron donor and acceptor pair are called what?

Answer 25

conjugate redox pair

Question 26

what is the equilibrium constant for a redox reaction called?

Answer 26

the standard reduction potential (Eo; "E-naught")

Question 27

what is Eo a measure of?

Answer 27

the tendency of a donor agent to lose its electrons

Question 28

a more negative Eo, the better electron ________ it is. the more positive, the better _________ it is

Answer 28

donor; acceptor

Question 29

does NADH have a positive or negative Eo? what about O2?

Answer 29

- NADH: negative - O2: positive - when electrons move from NADH to O2, energy is made available

Question 30

the first electron carrier in the ETC has the most ___________ Eo (hint: it's NADH)

Answer 30

negative

Question 31

the first electron carrier in the ETC is _________ when electrons are moved onto the next carrier

Answer 31

oxidized (OIL RIG)

Question 32

where does the electron transport chain take place in bacterial and archaeal cells? how about eukaryotic cells?

Answer 32

- plasma membranes - mitochondrial (or chloroplast) membranes

Question 33

what does NAD(P) stand for?

Answer 33

nicotinamide adenosine dinucleotide (phosphate)

Question 34

an important consequence of the ETC is the formation of a __________ __________

Answer 34

proton gradient

Question 35

during oxidation of NADH, protons are transported _____ ___ the cell. they ________ the cell through ATP synthase and generate ATP

Answer 35

out of; re-enter

Question 36

reactions can be linked together to form ______________ __________

Answer 36

biological pathways

Question 37

what are three biological pathway orientations?

Answer 37

- linear - cyclic - branched

Question 38

what are enzymes?

Answer 38

molecules that speed up reactions

Question 39

enzymes can be made from ________ or _____ (___________)

Answer 39

protein or RNA (ribozymes)

Question 40

what are protein catalysts?

Answer 40

highly specific substrates that increase the rate of a rxn without being permanently altered

Question 41

what are substrates? products?

Answer 41

- substrates: reacting molecules - products: substances formed by the reaction

Question 42

what is an apoenzyme?

Answer 42

the protein component of an enzyme

Question 43

what is a cofactor?

Answer 43

non-protein component of an enzyme

Question 44

what are two types of cofactors?

Answer 44

- prosthetic group: firmly attached - coenzyme: loosely attached; can act as carriers/shuttles

Question 45

what is a holoenzyme?

Answer 45

apoenzyme + cofactor

Question 46

what are the six general classes of enzymes?

Answer 46

- oxidoreductases - transferases - hydrolases (breakdown using water) - lyases (breakdown w/o water) - isomerases - ligases

Question 47

what does the transition state complex resemble in a reaction?

Answer 47

it resembles both the substrates and the products

Question 48

what is the activation energy of a reaction?

Answer 48

the energy required to form the transition state complex

Question 49

how do enzymes speed up reactions?

Answer 49

by lowering the activation energy (Ea)

Question 50

what are three environmental factors that significantly impact enzyme activity?

Answer 50

- substrate concentration - pH - temperature

Question 51

what are the effects of substrate concentration on enzyme activity?

Answer 51

- the rate of a rxn increases as the substrate conc. increases - it stops increasing when all enzyme molecules are saturated with substrate

Question 52

how do pH and tempertaure affect enzyme activity?

Answer 52

the enzyme can be denatured if the pH or temp goes outside its specific range that it can tolerate

Question 53

what are the three important mechanisms of metabolism for conservation of energy?

Answer 53

- metabolic channeling - regulation of the synthesis of a particular enzyme (transcription or translation) - direct stimulation or inhibition of the activity of the activity of a critical enzyme (post-translational)

Question 54

what is compartmentation?

Answer 54

differential distribution of enzymes and metabolites among other cell structures and organelles

Question 55

what the the two types of reversible post-translation regulation of enzyme activity?

Answer 55

- allosteric regulation - covalent modifications

Question 56

what is an allosteric effector?

Answer 56

a small molecule that non-covalently binds to the regulatory site, changing the shape of the enzyme and altering its catalytic activity - positive effector: increases enzymatic activity - negative effector: inhibits

Question 57

what is covalent modification of an enzyme?

Answer 57

- addition or removal of a chemical group (example: phosphate, methyl, adenylyl) - reversible on and off switch

Question 58

what is feedback inhibition (end-product inhibition)?

Answer 58

when the product builds up and inhibits the pathway

Question 59

what is a pacemaker enzyme?

Answer 59

an enzyme that catalyzes the slowest step/rate-limiting reaction in a pathway