Chapter 2 b (extra practice)

Question 1

Many reactions are energetically ____ and can only proceed with addition energy unit

Answer 1

unfavorable

Question 2

if delta G is negative then the reaction will proceed in what direction?

Answer 2

in the forward direction

Question 3

if delta G is positive then the reaction will proceed in what direction?

Answer 3

the reverse direction

Question 4

many biological reactions are thermodynamically (unfavorable or favorable)?

Answer 4

unfavorable., meaning delta G i sp ositive.

Question 5

If many biological reactions are unfavorable how can you get them to be favorable?

Answer 5

you can couple the reactions so that they become energetically favorable reactions

Question 6

____________- plays a central role in storing free energy in the cell

Answer 6

adenosine 5-triphosphate (ATP)

Question 7

the bond between ____________ in ATP are __________ energy bonds; their hydrolysis is accompanied by large decrease in free energy

Answer 7

bond between the phosphates

high energy bonds

Question 8

Other coenzymes are involved in the transfer of a variety of chemical groups. Many coenzymes are closely related to vitamins which_______________-

Answer 8

contribute part or all of the structure of the coenzyme

Question 9

in ___________ ____________ , the product of a metabolic pathway inhibits an enyzme involved in its synthesis

Answer 9

feed back inhibition

Question 10

feed back inhibition is a type of ______________ enzyme activity is controlled by the binding of small molecules to regulatory sites on the enzyme

Answer 10

allosteric regulation

Question 11

the changes the conformation of the enzyme alters _________ site

Answer 11

activation

Question 12

Phosphorlation is a _____ of enzyme regulation

Answer 12

a common mechanism

Question 13

phosphate groups are attached to the side chain OH groups of what three amino acid residues?

Answer 13

serine, threonine, tyrosine

Question 14

Does phosphorylation (stimulate, inhibit or both ) the activities of many enzymes?

Answer 14

it can either simulate or inhibit

Question 15

define coenzyme

Answer 15

small organic molecules that work together with enzymes to enhance reaction rates.

Question 16

are coenzymes altered by the reaction?

Answer 16

no the coenzymes are not altered by the reaction

Question 17

nicotinamide adenine dinucleotide (NAD) is a __________________

Answer 17

is a coenzyme that carreis electreons in the oxidation-reduction reactions

Question 18

NAD+ can accept _____ and ______ from one substrate, forming NADH

Answer 18

H+, two electrons

Question 19

NADH can then donate the________ to the second substrate, reforming NAD+

Answer 19

electrons

Question 20

Does NAD+ act as a oxidizing or reducing agent

Answer 20

oxidizing agent

Question 21

Does NADH act as a oxidizing or reducing agent ?

Answer 21

reducing agent

Question 22

what are the three amino acids involved in the cleave of peptides with the enzymes chymotrypsin?

Answer 22

-Serine (neutral, has OH group). It is able to loose a hydrogen and make a bond to break the peptide bond, thus freeing the peptide.

histidine (recieves Serine’s H and donates it to aspartate),

aspartate (basic)

*reaction reverses and the rest of the peptide is released.

Question 23

active sites may bind other small molecules that participate in ____________`

Answer 23

catalysis

Question 24

define prosthetic group

Answer 24

small molecules bound to proteins that have critical functional rules

Question 25

in myoglobin and hemoglobin the prosthetic group is ______, which carries ____

Answer 25

prosthetic group is heme…. it carries O2

Question 26

_____________ (zinc or iron) can be bound to enzymes and play a role in catalysis

Answer 26

metal ions