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BIO108- GENERAL PHYSIOLOGY > LECTURE 4: ENZYMES > Flashcards

LECTURE 4: ENZYMES Flashcards

1
Q

diverse group of water-insoluble
biological molecules; fats – energy stores;
phospholipids and sterols – major
components of membrane

A

Lipids

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2
Q

What are the biological molecules?

A

-Lipids
-Proteins
-Carbohydrates
-Nucleic Acid

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3
Q

energy stores

A

fats

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4
Q

major components of membrane.

A

phospholipids and sterols

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5
Q

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

A

Carbohydrates

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6
Q

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

A

Proteins

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7
Q

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

A

Nucleic acid

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8
Q

_____ carries coded information,
arranged into _______

A

-DNA
-Genes

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9
Q

instrumental in
translating the coded message of DNA into
sequences of amino acids during synthesis of
protein molecules

A

RNA

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10
Q

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

A

Catalysis

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11
Q

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

A

Catalyst

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12
Q

➢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

A

Enzymes

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13
Q

➢the kinetic energy required to bring the
reactants into position to interact.
➢measured as the number of calories required
to bring all the molecules in a mole of reactant
at a given temperature to a reactive (or
activated) state

A

Activation energy/free energy of activation

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14
Q

How do enzymes hasten the reaction?

A

➢ enzyme lowers
the activation
energy

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15
Q

Write this in formula:
➢enzyme (E) binds with a substrate (S) to
form an activated enzyme-substrate
complex (ES).
➢ES state, the path to the product (P) has a
lower activation energy than the
nonenzymatic reaction.

A

S (substrate) + E (enzymes) ➢ ES (enzyme substrate complex) ➢ P (product) + E (enzyme)

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16
Q

reactions catalyzed by enzymes are usually
_____________ times faster than uncatalyzed
reactions.

A

10^3 to 10^17

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17
Q

each enzyme is specific for a certain
substrate (reactant molecule)
➢ specificity of enzymes varies
e.g. stereo-specific
single product
specific bonds

A

Enzyme Specificity

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18
Q

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

A

active site

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19
Q

side groups 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.

A

Enzyme Specificity

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20
Q

catalytic potency
of an enzyme

A

enzyme activity

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21
Q

number of
reactions catalyzed per second by the
enzyme

A

turnover number

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22
Q

➢substrate interacts with the active site of the
enzyme
➢forming an enzyme-substrate complex (ES)
➢product separates from the enzyme
➢free enzyme can form an ES complex with a
new substrate molecule

A

Enzymatic Reaction

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23
Q

Enzymatic Reaction

A

S (substrate) + E (enzymes) ➢ ES (enzyme substrate complex) ➢ P (product) + E (enzyme

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24
Q

How enzymes accelerate reactions?

A

➢ 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

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25
Q

Factors affecting enzyme activity

A
  1. Temperature and Reaction
  2. Enzymes and Cofactors
  3. Enzyme Kinetics
  4. Enzyme Inhibition
  5. Regulation of Metabolic Reactions
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26
Q

➢rate of chemical reaction depends on
this.
➢ Increase temperature ➢ increase average of molecular velocity ➢ increase in number of molecular collisions per unit ➢ increase probability of successful interaction of the reactant
molecules.
➢as their velocities increase, the molecules
possess higher kinetic energies and thus are
more likely to react upon collision

A

Temperature and Reaction Rates

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27
Q

➢as temperature ________, reaction rate initially increases (increased kinetic energy of the substrate
molecule)

A

increases

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28
Q

➢as temperature increases further, reaction rate _________________

A

decreases (onset of denaturation)

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29
Q

➢reaction rate is maximal at the ___________

A

optimal
temperature

30
Q

➢drop in_____ exposes more positive sites on an enzyme for interaction with negative groups on a substrate molecule.

A

pH

31
Q

➢rise in pH facilitates the binding of ______ on a substrate to negative sites on the
enzymes.

A

positive
groups

32
Q

enzymes require________ for activity

A

cofactors

33
Q

small organic molecules
that act as cofactors

A

coenzymes

34
Q

enzyme minus its cofactor;
cannot function without its
cofactor/coenzyme

A

apoenzyme

35
Q

covalently attached
cofactors, part of the enzyme molecule
metal ions

A

vitamins

36
Q

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

A

holoenzyme

37
Q

Some Enzymes requiring Ca^2+

A

-Phosphodiesterase
-Protein Kinase C

38
Q

Some Enzymes requiring Cu^2+ (Cu+)

A

-Cytochrome
-Tyrosinase

39
Q

Some Enzymes requiring Fe^2+ or Fe^3+

A

-Catalase
-Cytochromes
-Ferredoxin
-Peroxidase

40
Q

Some Enzymes requiring K+

A

Pyruvate Phosphokinase (also requires Mg^2+)

41
Q

Some Enzymes requiring Mg^2+

A

-Phosphohydrolases
-Phosphotransferases

42
Q

Some Enzymes requiring Mn^2+

A

-Arginase
-Phosphotransferases

43
Q

Some Enzymes requiring Na+

A

-Plasma Membrane ATPase (also requires K+ and Mg^2+)

44
Q

Some Enzymes requiring Zn^2+

A

-Alcohol dehydrogenases
-Carbonic anhydrase
-Carboxypeptidase

45
Q

Metal Ions Functioning as cofactors

A

-Calcium (Ca^2+)
-Cupric Ion (Cu2+ (Cu+)
- Ferrous Cation (Fe2+) or Ferric Cation (Fe3+)
-Potassium (K+)
-Magnesium (Mg2+)
-Manganese (Mn2+)
-Sodium (Na+)
-Zinc (Zn2+)

46
Q

Oxidation reaction

A

Oxidoreductases

47
Q

Group Transfer

A

Transferase

48
Q

Hydrolysis Reaction (transfer of functional groups to water)

A

Hydrolases

49
Q

Additional or removal of groups to form double bonds

A

Lyases

50
Q

Isomerization (intramolecular group transfer)

A

Isomerases

51
Q

Ligation of two substrate at the expense of ATP hydrolysis

A

Ligases

52
Q

Six Major Classes of Enzymes

A

-Oxidoreductases
-Transferase
-Hydrolases
-Lyases
-Isomerase
-ligases

53
Q

Example of Oxidoreductases

A

Lactate Dehydrogenases

54
Q

Example of Transferase

A

Nucleoside monophosphate kinase (NMP kinase)

55
Q

Example of Hydrolases

A

Chymotrypsin

56
Q

Example of Lyases

A

Fumarase

57
Q

Example of Isomerases

A

Triose phosphate isomerase

58
Q

Example of Ligases

A

Aminoacyl-tRNA synthetase

59
Q

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

A

Enzymes Kinetics

60
Q

➢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

A

Enzyme Inhibition

61
Q

Two types of enzyme inhibition

A

-Competitive
-noncompetitive

62
Q

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

A

Competitive inhibition

63
Q

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

A

Noncompetitive inhibition

64
Q

Regulation of Metabolic reactions

A
  1. Control of Enzyme Synthesis
  2. Control of Enzyme Activity
65
Q

➢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

A

Control of Enzyme Synthesis

66
Q

➢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

A

Control of Enzyme Activity

67
Q

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

A

allosteric site

68
Q

➢ 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

A

End-product (Feedback) Inhibition

69
Q

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

A

allosteric inhibitor

70
Q

several cat-ion cofactors
act as allosteric activators
for some enzymes

A

Enzyme Activation

71
Q

Two kinds of energy-yielding metabolic
pathways in animal
tissues:

A
  1. Aerobic metabolism
  2. anerobic metabolism

BIO108- GENERAL PHYSIOLOGY (5 decks)

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