Exam 1

Question 1

Virtually all reactions in the body are mediated by _________

Answer 1

Enzymes

Question 2

___________ increase the rate of reaction but remain ________ by the overall process

Answer 2

Enzymes; unchanged

Question 3

Enzymes catalyse all ______ _______

Answer 3

Metabolic events

Question 4

Enzymes are __________ for their __________

Answer 4

Selective; substrates

Question 5

What is the suffix for an enzyme?

Answer 5

Ase

Question 6

What is a holoenzyme?

Answer 6

An active enzyme with its nonprotein component

Question 7

What is an apoenzyme?

Answer 7

An enzyme without its nonprotein component and it is inactive

Question 8

What is a cofactor?

Answer 8

If the nonprotein moiety is a metal ion - cofactor

Question 9

What is a coenzyme?

Answer 9

If the nonprotein moiety is a small organic molecule - coenzyme

Question 10

The active site

Answer 10

A pocket or groove on the surface of the protein into which the substrate fits. Specificity of an enzyme is controlled by its structure

Question 11

Lock and Key Model

Answer 11

The enzymes tertiary structure consists of a unique pocket or site which is tailer-made to fit only its substrate

Question 12

Induced-Fit Model

Answer 12

As enzymes interact substrates, they change their conformation such that the enzyme is snug around the substrate

Question 13

The combination of substrate and enzyme creates a new reaction pathway with a __________ transition state energy

Answer 13

Lowered

Question 14

Enzyme Kinetics are affected by

Answer 14

Temp and pH
Enzyme concentration
Subtrate concentration

Question 15

Temp and pH

Answer 15

Each enzyme reaction has an optimum pH and temperature. Extremes disrupt enzyme structure

Question 16

Enzyme concentration

Answer 16

At saturating substrate concentration, the initial velocity is directly related to enzyme concentration. As long as substrate is not limiting more enzyme leads to more product

Question 17

Substrate Concentration

Answer 17

The rate can be increased by adding more substrate, or by removing product as it is formed

Question 18

What is enzyme saturation?

Answer 18

When the active sites on all enzymes are engaged, this is called enzyme saturation

Question 19

Michaelis-Menton Model

Answer 19

The rate equation for a one-substrate enzyme-catalyzed reaction

Question 20

Low Km

Answer 20

High affinity because a low substrate is needed to half saturate the enzyme and tight binding. More efficiency

Question 21

High Km

Answer 21

Low affinity and weak binding. Low efficiency

Question 22

What is an inhibitor?

Answer 22

Any substance that can diminish the velocity of an enzyme-catalyzed reaction

Question 23

Irreversible inhibitors have what kind of bond?

Answer 23

Covalent

Question 24

Reversible inhibitors have what kind of bond?

Answer 24

Non-covalent bonds

Question 25

What are the two types of inhibition?

Answer 25

Competitive and non-competitive

Question 26

Competitive Inhibition

Answer 26

Inhibitor binds reversibly to the same site as substrate. Increases Km for a given substrate, so more substrate is needed to reach Vmax.

Question 27

Non-Competitive Inhibiton

Answer 27

Inhibitor and substrate bind to different sits on the enzyme. Inhibitor can bind to either free enzyme, thus preventing reaction. Decreases Vmax because it can't be overcome by increasing substrate.

Question 28

What is an allosteric enzyme?

Answer 28

Regulated by molecules called effectors or modifiers that bind non-covalently to sites other than the active sites

Question 29

What are the two types of effectors?

Answer 29

Negative and positive

Question 30

Negative Effector

Answer 30

Inhibit enzyme activity - takes more substrate to get to 1/2 Vmax, higher K

Question 31

Positive Effector

Answer 31

Increases enzyme activity - takes less substrate to get to 1/2 Vmax, lower K

Question 32

Homotropic Effectors

Answer 32

Substrate serves as effector, enhancing other substrate-binding sites

Question 33

Heterotropic Effectors

Answer 33

Effector different from substrate, effector may be the product, feeds back to cause inhibition

Question 34

An acid is an electron pair _________

Answer 34

Acceptor

Question 35

A base is an electron pair ________

Answer 35

Donor

Question 36

Electrophile

Answer 36

A lewis acid which seeks electrons

Question 37

Nucleophile

Answer 37

A lewis base, which seeks substances that are electron deficient

Question 38

Acid/Base reactions produce?

Answer 38

Water, salt and sometimes carbon dioxide

Question 39

What is a strong acid?

Answer 39

It 100% ionizes in water

Question 40

What is a weak acid?

Answer 40

Only a small % is ionized in water

Question 41

The Acid/Base Dissociation Constant

Answer 41

The relationship between the relative concentrations of the reactants and products is a temperature dependent constant

Question 42

The stronger the acid or base, the _____ the value os the dissociation constant

Answer 42

Larger

Question 43

Keq greater than 1

Answer 43

Favors the product

Question 44

Keq less than 1

Answer 44

Favours the reactants

Question 45

Le Chatelier's Principle

Answer 45

If a chemical in equilibrium is disturbed, the system will adjust to restore equilibrium

Question 46

What two things alter the equilibrium?

Answer 46

Change in concentration of reactants or products, change in temperature

Question 47

pH

Answer 47

A measure of a solutions acidity. The -log of H+. The lower the pH the higher the acidity

Question 48

pH of the body is ____?

Answer 48

7.4

Question 49

Buffer

Answer 49

A buffer solution has the ability to resist changes in pH upon the addition of small amounts of either acid or base

Question 50

A buffer solution needs 2 things

Answer 50

1. A weak acid or a weak base 2. The salt of the weak acid or weak base (the conjugate)

Question 51

Why Buffer?

Answer 51

Many reactions in living organisms proceed normally only in a narrow pH range. A change in pH or the aqueous solution of a living organism can be fatal. Living organisms need a mechanism to keep the pH of their physiological solutions relatively constant

Question 52

KA

Answer 52

Dissociation constant of the weak acid

Question 53

KB

Answer 53

Dissociation constant of the weak base

Question 54

What are the 3 Homeostatic Regulators of H+?

Answer 54

1. Chemical buffer systems 2. Respiratory mechanism 3. Renal mechanism

Question 55

Chemical Buffer Systems

Answer 55

The first to respond, takes less than 1 second, temporarily ties up excess acids and bases

Question 56

3 main systems of chemical buffer systems

Answer 56

1. Carbonic acid 2. Phosphate 3. Protein

Question 57

Respiratory Mechanism

Answer 57

Second to respond, takes 1-3 minutes, respiratory centre involved, removes CO2 and H2CO3

Question 58

Renal Mechanism

Answer 58

Third to respond but not potent, takes hours to days, kidneys remove metabolic acids

Question 59

Phosphate Buffer System

Answer 59

Important in tubular fluids of kidneys and ICF

Question 60

Carbonic Acid Bicarbonate Buffer System

Answer 60

Most important in the ECF, the most significant buffering compound in the blood

Question 61

Bloods buffering capability is dependent on the equilibrium between?

Answer 61

1. CO2 dissolved in the blood and carbonic acid as a product of CO2 and water 2. Carbonic acid and bicarbonate as a product of H+ dissociation

Question 62

The role of the kidneys

Answer 62

Assist acid-base balance by regulation/excretion of bicarbonate and NH4+

Question 63

If larger numbers of bicarbonate ions are filtered by the kidneys and excreted into the urine, this removes _____ from the _____

Answer 63

Base; blood

Question 64

If larger numbers of hydrogen ions are filtered by the kidneys and excreted into the urine, this removes _____ from the _____

Answer 64

Acid; blood

Question 65

Protein Buffer Systems - 3 types

Answer 65

1. Plasma 2. Amino acid 3. Hemoglobin