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Biology gr12 > Enzymes > Flashcards

Enzymes Flashcards

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1
Q

Some spontaneous chemical reactions occur at nearly imperceptibly _____ rates. ie. rusting

A

slow

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2
Q

The rate of many metabolically important chemical reactions is _________ to sustain life.

A

insufficient

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3
Q

What is activation Energy

A

is the minimum amount of energy required to start a chemical reaction, and also the energy required to break bonds

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4
Q

(EA) stands for…

A

activation energy

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5
Q

all reactions possess an _____ barrier that must be overcome for a reaction to occur

A

activation energy

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6
Q

energy is released when new bonds are….

A

formed

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7
Q

Enzymes are protein ….

A

catalysts

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8
Q

all enzymes are proteins, but not all proteins are…….

A

enzymes

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9
Q

What is a catalyst

A

A substance that speeds up the rate of a chemical reaction without being used up (consumed) in the reaction

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10
Q

after a reaction, the enzyme is able to catalyze……

A

another reaction

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11
Q

enzyme names end in

A

ase

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12
Q

Every chemical reaction involves both

A

making and breaking bonds

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13
Q

making bonds ________ energy

A

releases

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14
Q

breaking bonds ________ energy

A

absorbs

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15
Q

speed up the rate of a reaction by
lowering the………

A

activation energy

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16
Q

What remains the same in the chart

A

the net change in enthalpy

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17
Q

Enzymes are proteins with…

A

specific 3-D shapes

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18
Q

What is a substrate?

A

the reactant that an enzyme acts on when it catalyzes a chemical reaction

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19
Q

Enzymes are defined by…

A

chemical bonds

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20
Q

A substrate binds to a …..

A

particular site

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21
Q

enzymes are _______ for the substrate to which they
bind

A

specific

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22
Q

location to where the substrate binds to the enzyme is known as the……

A

active site (complimentary fit)

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23
Q

What is Enzyme-Substrate Complex?

A

forms when an enzyme binds to its specific substrate, allowing a chemical reaction to occur.

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24
Q

1st theory of active site

A

active site is rigid and exactly
complimentary to the substrate (lock and key)

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25
Q

What is Induced-fit Model?

A

is when an enzyme changes its shape slightly to better fit the substrate, helping the reaction occur.

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26
Q

Steps of enzymes and substrates

A
  1. Enzyme and substrate are available.
  2. Substrate enters the active site and forms weak bonds
    while the enzyme’s conformation changes to
    accommodate the substrate.
  3. Bond(s) are either broken or formed within the
    substrate.
  4. Altering the bonds within the substrate alters the
    conformation of the protein slightly; loses affinity for
    product and releases the molecules.
27
Q

Induced fit is basically..

A

when enzymes conformation changes to better accommodate the substrate

28
Q

Rates of chemical reactions are dependent on the what factors?

A

temperature

pH

concentration of substrate

concentration of enzyme

Inhibitors

Cofactors/Coenzymes

29
Q

Which chemical reaction are denaturation?

A

temperature and pH

30
Q

An enzyme’s three-dimensional shape is defined by various….

A

chemical bonds

31
Q

The rate at which an enzyme converts substrate into product can be increased by ___________________.

A

increasing substrate concentration

there is a limit !

32
Q

Enzyme is saturated when….

A

all active sites are occupied by substrates, and the reaction rate can’t increase any further.

33
Q

Adding more _______ will not increase the rate. But, Adding more _____ will increase the rate.

A

substrate, enzyme

34
Q

Cofactors may be…

A

inorganic or organic

35
Q

What is cofactor ?

A

nonprotein chemical compound that helps enzymes to function and work properly.

36
Q

What is coenzymes

A

organic nonprotein cofactors
that help some enzymes to function

often comes from vitamins

37
Q

Inorganic cofactors are typically…

A

metal ions or molecules

38
Q

Organic cofactors (“coenzymes”) are typically…

A

vitamins or are derived from vitamins.

39
Q

What is Competitive
Inhibition?

A

substances that compete with the substrate for an enzyme’s active site

40
Q

increased [substrate] can
overcome present…

A

inhibitors

41
Q

What is noncompetitive Inhibition?

A

when the inhibitor binds to a site on the enzyme that is not the active site

42
Q

Noncompetitive inhibition causes a change in…

A

enzyme shape

43
Q

When noncompetitive inhibitor changes the shape of enzyme, what happens?

A

It cannot bind to the substrate

44
Q

What is Allosteric Regulation?

A

when a molecule binds to an enzyme at a site other than the active site, changing the enzyme’s activity by either activating it or inhibiting it.

45
Q

allosteric regulation can

A

activate or inhibit

46
Q

Regulator binding changes shape of

A

substrate active site

47
Q

What is an allosteric activator ?

A

a substance that binds to an allosteric site on an enzyme and stabilizes the protein conformation
that keeps all the active sites available to their
substrates

This increases enzyme activity

48
Q

active form is stabilized by an

A

allosteric activator molecule

49
Q

inactive form is stabilized by an …

A

allosteric inhibitor molecule

50
Q

What are Allosteric Inhibitors?

A

a substance that binds to an allosteric site on an enzyme and stabilizes the inactive form of the enzyme

51
Q

Allosteric inhibitor vs activator

A

Allosteric activator stabilizes the protein conformation that keeps all the active sites available to their
substrates.

While allosteric inhibitor stabilizes the inactive form of the enzyme

52
Q

many poisons act by…

A

inhibiting enzymes

53
Q

DDT inhibits key enzymes in…

A

nervous system

54
Q

many antibiotics inhibit….

A

bacterial enzymes

55
Q

What is Feedback Inhibition?

A

Feedback inhibition is when the end product of a process inhibits an enzyme earlier in the pathway, stopping the process to prevent overproduction.

56
Q

When is end product produced in feedback inhibition

A

when needed

57
Q

in many cases, this
end-product acts as an
_________ of an enzyme

A

Inhibitor

58
Q

What is exothermic (Exergonic) reaction?

A

When the reactant is higher than the product, energy is released and makes bonds.

59
Q

What is endothermic (endergonic) reaction?

A

When the product is higher than the reactant, energy is absorbed and bonds are broken.

60
Q

Substrates act on what

A

sucrose

61
Q

Enzymes decrease _______________, but increases the _________________

A

activation energy, rate of reaction

62
Q

Substrates come to enzymes or enzymes come to substrates?

A

Substrates come to enzymes, not the other way around. The concentration remains the same

63
Q

Enzyme pH in stomach is..

A

2

64
Q

When you remove on phosphate from ATP, what does it become?

A

ADP

Biology gr12 (22 decks)

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