Enzymes

Question 1

are proteins that increase the rate of reaction by lowering the energy of activation

Answer 1

enzymes

Question 2

They catalyze nearly all the chemical reactions taking place in the cells of the body

Answer 2

enzymes

Question 3

they have unique three-dimensional shapes that fit the shapes of reactants (substrates)

Answer 3

Enzymes

Question 4

shape of enzymes

Answer 4

globular

Question 5

complex structure of enzyme

Answer 5

3D

Question 6

The substrate of an enzyme are the ______ that are activated by the enzyme

Answer 6

reactants

Question 7

Enzymes are _______ to their substrates

Answer 7

specific

Question 8

The specificity of enzyme is determined by the?

Answer 8

active site

Question 9

The name of an enzyme identifies the reacting substance
- usually ends in?

Answer 9

-ase

Question 10

Enzymes are classified according to the?

Answer 10

type of reaction they catalyze

Question 11

Oxidation-reduction is classified as?

Answer 11

Oxidoreductases

Question 12

Transfer groups of atoms is classified as?

Answer 12

transferases

Question 13

hydrolysis is classified as?

Answer 13

hydrolases

Question 14

addition and removal of atoms from a double bond is classified as?

Answer 14

lyases

Question 15

rearranging atoms is classified as?

Answer 15

isomerases

Question 16

using atp to combine molecules is classified as?

Answer 16

ligases

Question 17

a region within an enzyme that fits the shape of substrate molecules

Answer 17

active site

Question 18

Amino acid side-chains align to bind the _____ through H-bonding, salt-bridges, hydrophobic interactions, etc.

Answer 18

substrate

Question 19

are released when the reaction is complete (they no longer fit well in the active site)

Answer 19

Products

Question 20

Enzymes have varying degrees of ______ for substrates

Answer 20

specificity

Question 21

Enzymes may recognize and catalyze:

Answer 21

• a single substrate
  
  • a group of similar substrates
  • a particular type of bond

Question 22

types of enzyme specificity

Answer 22

1. absolute
2. group
3. linkage

Question 23

Catalyze one type of reaction for a
single substrate
ex: Urease catalyzes only the
hydrolysis of urea

Answer 23

absolute

Question 24

Catalyze one type of reaction for
similar substrates
ex: Hexokinase adds a phosphate
group to hexoses

Answer 24

group

Question 25

Catalyze one type of reaction for a specific type of bond ex: Chymotrypsin catalyzes the hydrolysis of peptide bonds

Answer 25

linkage

Question 26

In the ________ of enzyme action: - the active site has a rigid shape - only substrates with the matching shape can fit - the substrate is a key that fits the lock of the active site

Answer 26

lock-and-key model

Question 27

This is an older model, however, and does not work for all enzymes

Answer 27

Lock-and-Key Model

Question 28

In the __________ of enzyme action: - the active site is flexible, not rigid - the shapes of the enzyme, active site, and substrate adjust to maximize the fit, which improves catalysis - there is a greater range of substrate specificity

Answer 28

induced-fit model

Question 29

This model is more consistent with a wider range of enzymes

Answer 29

induced-fit model

Question 30

When a substrate (S) fits properly in an active site, an __________ is formed

Answer 30

enzyme-substrate (ES) complex

Question 31

Within the active site of the ES complex, the reaction occurs to convert substrate to?

Answer 31

product (P)

Question 32

The products are then released, allowing another ________ to bind the enzyme - this cycle can be repeated millions (or even more) times per minute

Answer 32

substrate molecule

Question 33

are different forms of an enzyme that catalyze the same reaction in different tissues in the body

Answer 33

isoenzymes

Question 34

they have slight variations in the amino acid sequences of the subunits of their quaternary structure •For example, lactate dehydrogenase (LDH), which converts lactate to pyruvate, consists of five isoenzymes

Answer 34

isoenzymes

Question 35

An additional non-protein molecule that is needed by some enzymes to help the reaction

Answer 35

cofactors

Question 36

Tightly bound cofactors are called?

Answer 36

prosthetic groups

Question 37

Cofactors that are bound and released easily are called?

Answer 37

coenzymes

Question 38

Many vitamins are?

Answer 38

coenzymes

Question 39

The levels of ______ in the blood can be used to determine the amount of damage in specific tissues

Answer 39

diagnostic enzymes

Question 40

Enzymes are most active at an optimum temperature

Answer 40

usually 37°C in humans

Question 41

enzyme show little activity at?

Answer 41

low temperatures

Question 42

Activity is lost at high temperatures as _________ occurs

Answer 42

denaturation

Question 43

Enzymes are most active at?

Answer 43

optimum pH

Question 44

Amino acids with _________ have the proper charges when the pH is optimum

Answer 44

acidic or basic side-chains

Question 45

Activity is lost at low or high pH as _________ is disrupted

Answer 45

tertiary structure

Question 46

Most enzymes of the body have an optimum pH of about? However, in certain organs, enzymes operate at lower and higher optimum pH values

Answer 46

7.4

Question 47

The rate of reaction increases as _______ increases (at constant substrate concentration)

Answer 47

enzyme concentration

Question 48

At higher enzyme concentrations, more enzymes are available to _____ the reaction (more reactions at once)

Answer 48

catalyze

Question 49

There is a ______ between reaction rate and enzyme concentration (at constant substrate concentration)

Answer 49

linear relationship

Question 50

The rate of reaction increases as _______ increases (at constant enzyme concentration)

Answer 50

substrate concentration

Question 51

__________ occurs when the enzyme is saturated (when all enzymes are binding substrate)

Answer 51

Maximum activity

Question 52

The relationship between reaction rate and substrate concentration is? (levels off) when the enzyme is saturated

Answer 52

exponential, and asymptotes

Question 53

are molecules that cause a **loss of enzyme activity**

Answer 53

inhibitors

Question 54

They prevent substrates from fitting into the active site of the enzyme

Answer 54

inhibitors

Question 55

goes on and off, allowing the enzyme to regain activity when the inhibitor leaves

Answer 55

reversible inhibitor

Question 56

reversible and has a structure like the substrate

Answer 56

competitive inhibitor

Question 57

it competes with the substrate for the active site

Answer 57

competitive inhibitor

Question 58

its effect is reversed by increasing substrate concentration

Answer 58

competitive inhibitor

Question 59

is a competitive inhibitor of succinate dehydrogenase - it has a structure that is similar to succinate - inhibition can be reversed by adding succinate

Answer 59

malonate

Question 60

has a structure that is different than that of the substrate

Answer 60

noncompetitive inhibitor

Question 61

noncompetitive inhibitor it binds to an? rather than to the active site

Answer 61

allosteric site

Question 62

it distorts the shape of the enzyme, which alters the shape of the active site and prevents the binding of the substrate

Answer 62

noncompetitive inhibitor

Question 63

The effect can not be reversed by adding more substrate

Answer 63

noncompetitive inhibitor

Question 64

destroys enzyme activity, usually by bonding with side-chain groups in the active site

Answer 64

irreversible inhibitor