4

Question 1

What are the Biological Molecules?

Answer 1

1. Lipids
2. Carbohydrates
3. Proteins
4. Nucleic acid

Question 2

diverse group of water-insoluble biological molecules

Answer 2

Lipids

Question 3

energy stores

Answer 3

fats

Question 4

major components of membrane

Answer 4

phospholipids and sterols

Question 5

polyhydroxyl aldehyde and ketones with the general formula of (CH2O)n.

Answer 5

Carbohydrates

Question 6

most complex and most abundant organic molecules containing at least one carboxyl group and one amino group.

Answer 6

Proteins

Question 7

carries coded information

Answer 7

DNA

Question 8

DNA carries coded information,
arranged into ________

Answer 8

genes

Question 9

DNA carries coded information, arranged into genes, that is passed from each cell to its daughter cells and from one generation to the next; RNA instrumental in translating the coded message of DNA into sequences of amino acids during synthesis of protein molecules

Answer 9

Nucleic acid

Question 10

The process of increasing the rate of reaction with the use of a catalyst.

Answer 10

Catalysis

Question 11

any substance that increases rate of reaction upon addition to a certain reaction.

Answer 11

Catalyst

Question 12

➢catalyst of biochemical reactions (biological catalysts)
➢neither used up in the reaction nor do they appear as reaction products
➢are proteins of very specific amino acid composition and sequence
➢ denatured and precipitated with salts,
solvents and other reagents
➢ catalyze all the synthetic and metabolic
reactions of the cell
➢ allows for a faster speed of reaction
➢ increases the reaction rates by means of
lowering the energy of activation

Answer 12

Enzymes

Question 13

Activation energy/free energy of activation

the kinetic energy required to bring the _____ into position to interact.

Answer 13

reactants

Question 14

Activation energy/free energy of activation

➢measured as the number of calories required to bring all the molecules in a mole of reactant at a given temperature to a __________

Answer 14

reactive (or activated) state.

Question 15

How do enzymes hasten the reaction?

Answer 15

enzyme lowers the activation energy

Question 16

How do enzymes hasten the reaction?

enzyme (E) binds with a substrate (S) to form an __________

Answer 16

activated enzyme substrate complex (ES*)

Question 17

How do enzymes hasten the reaction?

ES* state, the path to the product (P) has a __________ than the nonenzymatic reaction.

Answer 17

lower activation energy

Question 18

How do enzymes hasten the reaction?

reactions catalyzed by enzymes are usually _______ faster than uncatalyzed reactions.

Answer 18

103 to 1017 times

Question 19

General Propertied of Enzymes

**Enzyme Specificity

each enzyme is specific for a certain _______ (reactant molecule)

Answer 19

substrate

Question 20

General Propertied of Enzymes

specificity of enzymes varies

Answer 20

e.g.
stereo-specific
single product
specific bonds

Question 21

where the substrate can fit like a lock-and-key mechanism

Answer 21

active site

Question 22

___________ of certain amino acid residues that are brought into proximity by this tertiary structure, even though they may be widely separated in the
amino acid sequence of the enzyme.

Answer 22

side groups

Question 23

Mechanism of catalysis by enzymes

Answer 23

enzyme activity
turnover number –

Question 24

Mechanism of catalysis by enzymes

catalytic potency of an enzyme

Answer 24

enzyme activity

Question 25

**Mechanism of catalysis by enzymes** number of reactions catalyzed per second by the enzyme

Answer 25

turnover number

Question 26

How enzymes accerlerate reactions?

Answer 26

➢ holds substrates in close proximity to one another in order to enhance the probability of a reaction ➢ form an unstable intermediate that readily undergoes second reaction ➢ presence of proton donors and acceptors in the active site of the enzyme

Question 27

**Temperature and Reaction Rates** rate of chemical reaction depend on ________.

Answer 27

temperature

Question 28

**Temperature and Reaction Rates** ↑ temperature - ↑ average molecular velocity - ↑ number of molecular collisions per unit ↑ probability of successful interaction of the reactant molecules.

Answer 28

- as their velocities increase, the molecules possess higher kinetic energies and thus are more likely to react upon collision. - as temperature increases, reaction rate initially increases (increased kinetic energy of the substrate molecule) - as temperature increases further, reaction rate decreases (onset of denaturation) - reaction rate is maximal at the optimal temperature

Question 29

_____ in pH exposes more positive sites on an enzyme for interaction with negative groups on a substrate molecule.

Answer 29

drop

Question 30

______ in pH facilitates the binding of positive groups on a substrate to negative sites on the enzymes.

Answer 30

rise

Question 31

**Enzymes and Cofactors** enzymes require ____ for activity

Answer 31

cofactors

Question 32

**Enzymes and Cofactors** small organic molecules that act as cofactors

Answer 32

coenzymes

Question 33

**Enzymes and Cofactors** enzyme minus its cofactor; cannot function without its cofactor/coenzyme

Answer 33

apoenzyme

Question 34

**Enzymes and Cofactors** covalently attached cofactors, part of the enzyme molecule metal ions

Answer 34

e.g. vitamins

Question 35

Many enzymes require the presence of other ____

Answer 35

compounds

Question 36

(coenzyme, prosthetic group or metal ion)

Answer 36

Cofactor

Question 37

Cofactor (coenzyme, prosthetic group or metal ion) + apoenzyme = _______

Answer 37

holoenzyme

Question 38

Classified according to the types of reaction they catalyze

Answer 38

➢Oxidoreductase ➢Transferase ➢Hydrolase ➢Lyase ➢Isomerase ➢Ligase

Question 39

Oxidation-reduction

Answer 39

Oxidoreductase

Question 40

Group transfer

Answer 40

Transferase

Question 41

Hydrolysis reactions (transfer of functional groups to water)

Answer 41

Hydrolases

Question 42

Addition or removal of groups to form double bonds

Answer 42

Lyases

Question 43

Isomerization (intramolecular group transfer)

Answer 43

Isomerases

Question 44

Ligation of two substrates at the expense of ATP hydrolysis

Answer 44

Ligase

Question 45

The rate at which an enzymatic reaction proceeds depends on the concentrations of substrate, product, and active enzymes

Answer 45

Enzymes Kinetics

Question 46

➢used in the living cell as a means of controlling enzymatic reactions ➢discovered important features of the active sites and of the mechanisms of enzyme action ➢enzymes can be irreversibly (toxins) or reversibly inhibited

Answer 46

Enzyme Inhibition

Question 47

Two types of Enzyme Inhibition

Answer 47

1. competitive inhibition 2. noncompetitive inhibition

Question 48

➢caused by molecules that react directly with the active site of the enzyme ➢can be reversed by an increase in substrate concentration ➢most competetive inhibitors are substrate analogs

Answer 48

Competitive inhibition

Question 49

➢caused by molecules that bind to a region(s) of the enzym eoutside the active site ➢reversed by dilution or removal of the inhibitor ➢chemical structure of noncompetitive inhibitors typically differs from that of the substrate.

Answer 49

Noncompetitive inhibition

Question 50

What are the Regulation of Metabolic Reactions

Answer 50

1. Control of Enzyme Synthesis 2. Control of Enzyme Activity

Question 51

➢certain conditions that reduce protein synthesis generally ➢regulated at the molecular level by modulation of the rate of transcription of the gene encoding it (DNA is packaging; rate at which RNA is translated into proteins) ➢enzymes are only synthesized when needed

Answer 51

Control of Enzyme Synthesis

Question 52

➢regulated by modulator molecules (interact with a part of the enzyme molecule – allosteric site - distinct from the active site) ➢allosteric site - alters the tertiary structure of the enzyme thus changing the conformation of the active site ➢the affinity of the enzyme for its substrate decreases or increases

Answer 52

Control of Enzyme Activity

Question 53

alters the tertiary structure of the enzyme thus changing the conformation of the active site

Answer 53

allosteric site

Question 54

distinct from the active site

Answer 54

allosteric site

Question 55

➢ first enzyme of the sequence that acts as the regulatory enzyme ➢ end product of the pathway feeds back to inhibit the activity of this first enzyme ➢ limits the rate of accumulation of the end product by slowing the entire sequence from the beginning

Answer 55

End-product (Feedback) Inhibition

Question 56

interaction of the end product occurs in the allosteric site, making the end product an ______________

Answer 56

allosteric inhibitor

Question 57

**Enzyme Activation** several cat-ion cofactors act as __________ for some enzymes

Answer 57

allosteric activators

Question 58

Two kinds of energyyielding metabolic pathways in animal tissues:

Answer 58

1.aerobic metabolism 2. anaerobic metabolism

Question 59

food molecules are completely oxidized to carbon dioxide and water by molecular oxygen; energy yield is far greater

Answer 59

aerobic metabolism

Question 60

food molecules are oxidized incompletely to lactic acid (lactate); absence of oxygen

Answer 60

anaerobic metabolism