Enzyme Activity

Question 1

moles of
substrate converted to product per
unit time.

Answer 1

Enzyme Activity

Question 2

The _____ of appearance of product or the rate of disappearance of
substrate

Answer 2

rate

Question 3

Factors affecting enzyme activity

Answer 3

❖ Concentration of substrate
❖ Concentration of enzyme
❖ Temperature
❖ PH
❖ Activators
❖ Inhibitors

Question 4

For Non-enzymic reactions:

The increase in velocity is proportional to the ______________________

Answer 4

Substrate Concentration

Question 5

For Enzymic Reaction:

Faster reaction but it reaches the ________________ when all the enzyme molecules are ____________

Answer 5

saturation point ; occupied

Question 6

What equipment is used to test the absorbance?

Answer 6

Spectrophotometer

Question 7

For Enzymic Reaction:

If you alter the concentration enzyme the Vmax will ______________

Answer 7

change too

Question 8

The rate of reaction increases as ___________________________________________________________________

Answer 8

substrate concentration increases (at constant enzyme concentration)

Question 9

Maximum activity occurs when the enzyme is

Answer 9

saturated

Question 10

The relationship between reaction rate and substrate concentration is

Answer 10

exponential, and asymptotes (levels off) when the enzyme is saturated

Question 11

The initial rate of an enzymecatalyzed reaction is ________________________

Answer 11

always
proportionate to the concentration of enzyme.

Question 12

This property of enzyme is made use in determining the serum enzyme for the diagnosis of diseases.

Answer 12

[S]»[E] V∝[E]

Question 13

The rate of reaction increases as ______________________

Answer 13

enzyme concentration increases (at
constant substrate concentration)

Question 14

At ___________________________, more enzymes are available to catalyze the reaction (more reactions at once)

Answer 14

higher enzyme concentrations

Question 15

There is a linear relationship betweenn ____________________ (at constant substrate concentration)

Answer 15

reaction rate and enzyme concentration

Question 16

Enzymes are most active at an _______________________________

Answer 16

optimum temperature

Question 16

Lose activity at high temperatures as _____________ occurs

Answer 16

denaturation

Question 17

Enzymes shows little activity at ________________

Answer 17

low temperatures

Question 18

Effect of Temperature

Speed of reaction increases until an __________________________

Answer 18

Optimum temperature is reached

Question 19

Optimum temperature is the
temperature at ________________________

Answer 19

which the enzyme works best

Question 20

After this point the rate of reaction decreases until there is _____________

Answer 20

no reaction

Question 21

At this point enzyme is said to be
DENATURED which means?

Answer 21

active site destroyed

Question 22

Effect of temperature

A reaction rate will generally increase with increasing Temperature due to __________________________________________________________________________________________________________

Answer 22

increased kinetic energy in the system until a maximal velocity is reached.

Question 23

Above this maximum, the kinetic
energy of the system exceeds the energy
barrier for breaking weak H-bonds and
hydrophobic interactions, thus__________________________________________________________________________________________________________________________

Answer 23

leading to unfolding and denaturation of the enzyme and a decrease in reaction rate

Question 24

denature protein = ______________ = ______________________

Answer 24

unfold ; lose shape

Question 25

lower temperature, molecules move _________

Answer 25

slower

Question 26

Enzyme-controlled reactions follow
this rule as they are ___________________

Answer 26

chemical reactions

Question 27

The optimum temperature for an
enzyme-controlled reaction will be a
balance between the ______________________

Answer 27

Q10 and denaturation.

Question 28

For most enzymes (outside the
human body) the optimum
temperature is about _________

Answer 28

30°C

Question 29

Many are a lot lower, cold-water
fish will die at 30°C because _________________________

Answer 29

their enzymes denature

Question 30

A few bacteria have enzymes that
can withstand very high
__________________

Answer 30

temperatures up to 100°C

Question 31

Most enzymes however are fully
_____________________

Answer 31

denatured at 70°C

Question 32

Each enzyme has an ________________________

Answer 32

optimal pH or pH range

Question 33

Effect of pH

Variations in pH can affect a particular
enzyme in many ways, especially if ionizable
amino acid side chains are involved in
______________________________________

Answer 33

binding of the substrate and/or catalysis.

Question 34

Extremes of pH can also lead to denaturation
of an enzyme if the ionization state of ___________________________________________________________

Answer 34

amino acid(s) critical to correct folding are altered.

Question 35

changes in pH changes __________________

Answer 35

protein shape

Question 35

most human enzymes’ pH ranges ___________

Answer 35

6 to 8

Question 35

trypsin (small intestine) pH

Answer 35

8

Question 35

pepsin (stomach) pH

Answer 35

3

Question 36

Enzymes are most active at
______________________

Answer 36

optimum pH

Question 37

Amino acids with acidic or basic side-chains have the ________________________

Answer 37

proper charges when the pH is optimum

Question 37

Activity is lost at low or high pH as
_______________________________

Answer 37

tertiary structure is disrupted

Question 37

Most enzymes of the body have an
optimum pH of about ____________ However, in
certain organs, enzymes operate at
_______________________________________

Answer 37

7,4 ; lower and higher optimum pH values

Question 37

Enzyme activators are

Answer 37

molecules that bind to enzymes and increase their activity

Question 38

Enzyme Activators

Give Inorganic Ions (Metal Ions and Anions)

Answer 38

Metal Ions: Na+ , K+ , Mg2+ , Ca2+ , Cu2+ , Zn2+ , Fe2+

Anions: Cl- , Br-, I-, CN-

Question 39

Enzyme Activators

Give Organic Enzyme Activators

Answer 39

Cys , GSH

Question 40

any molecule which acts directly on an enzyme to lower its catalytic rate is called

Answer 40

an inhibitor

Question 40

Some enzyme inhibitors are

Answer 40

normal body matabolites

Question 40

are regulated by molecules
called effectors (modifiers) that binds
nonconvalently at a site other than the
active site.

Answer 40

Allosteric enzymes

Question 40

most frequently by the
addition or removal of phosphate group
to serine, threonine or tyrosine residue
of the enzyme by kinases. (enzyme)

Answer 40

Covalent Modification

Question 41

Cells can also regulate the
amount of enzymes present by altering
the rate of enzyme synthesis

Answer 41

Induction and repression of enzyme
synthesis

Question 42

Some enzyme are
synthesized as inactive precursor,
called zymogens, that are activated by
proteolysis (e.g., digestive enzyme,
pepsinogen is Inactive and cleaved to
pepsin which is active chymotrypsin)

Answer 42

Zymogen Cleavage

Question 42

Many enzymes are localized in specific
organelles within the cell. This,
compartmentation helps in the
regulation of the metabolic pathway.

Answer 42

Location within the cell

Question 42

are chemicals that reduce
the rate of enzymic reactions

Answer 42

Inhibitors