Enzymes (Chapter 3 )

Question 1

WHAT ARE ENZYMES

Answer 1

Enzymes are biological molecules

Question 2

WHAT IS THE DEFINITION OF BIOLOGICAL MOLECULES

Answer 2

Biological molecules are substances which speed up a chemical reaction by lowering the activation energy in living organisms without changing nor being used up

Question 3

WHAT KIND OF PROTEINS ARE ENZYMES

Answer 3

Enzymes are globular proteins

Question 4

WHAT ARE SUBSTRATES?

Answer 4

Substrates are substances on which Enzymes act.
E.g. Lipase act on lipids
Protease act on proteins

Question 5

WHAT ARE ACTIVE DOES ALSO KNOWN AS

Answer 5

They are known as catalytic sites.
It is were the reaction takes place

Question 6

STRUCTURE OF ENZYMES

Answer 6

Enzymes have a teritary structure and some enzymes have also have Quaternary structure

Question 7

ENZYMES ARE SPECIFIC TO THEIR ACTIONS.
WHAT PROPERTIES MAKE ENZYMES SPECIFIC IN THEIR ACTIONS?

Answer 7

Presence of specific active site - contain survivors sequence of amino acids in the polypeptide, folding of amino acids and form a 3D shape and specific bonds maintain its shape

Question 8

MECHANISM OF ENZYME ACTION

Answer 8

Enzyme + substrate —-> enzyme substrate complex —> formation of enzyme-product complex —> enzyme + product

Question 9

LOCK AND KEY MODEL

Answer 9

Enzyme = lock.
Substrates = key.
Fire the enzymes to work you need a specific substrate
In this principle, The active site is specific due to the specific sequence of amino acids and is rigid.

Question 10

INDUCED FIT MODEL

Answer 10

In this principle The substrate is partially complementary to the active site.
In this the active site of enzymes are slightly changeable, sure to it’s flexibility enzymes are slightly changeable.

Question 11

FACTORS AFFECTING ENZYMATIC ACTIVITY

Answer 11

1. Enzyme concentration:
   Concentration : Rate of reaction
2. Substrate concentration
   Substrate concentration : Rate of reaction
3. Temperature
   Temperature : Rate of reaction
4. pH
   Increasing or decreasing the pH slightly can denature the enzyme

Question 12

SUBSTRATE CONCENTRATION

Answer 12

• When every substrate is occupied by enzymes it is known as the substrate saturation.
• If as you increase the substrate concentration but the graph remains constant, this indicates that the enzyme concentration is limited ( enzyme acts as a limiting factor), and in order to increase the graph we should increase the enzyme concentration.
• Inc substrate/ enzyme concentration, collisions Inc, the ES complex formation Inc, and therefore the product amount per unit time Inc.

Question 13

TEMPERATURE

Answer 13

Temp Inc, K.E. Inc, random movement of enzymes and substrate Inc, effective collisions Inc, ES complex formation Inc, and product formation Inc, RoR Inc.

If temperature increases beyond optimum temperature then the enzyme bibs break and the active site shape changes and enzyme denatures.
H2 bonds break first, then ionic bonds and then peptide bonds.
Once the enzyme denatures it will not return to it’s original shape. However, if the enzyme is inactive it will become active of you one the temp.

Question 14

PH

Answer 14

If you slightly increase our decrease the pH then the enzyme immediately denatures.
When OH and H starts to form a bonds with the active site, it alerts the shaper of the active site. If the active site changes, no ES complex forms.

1-6 pH is acidic - have high concentration of H+
7pH is neutral - have equal concentration of H+ and OH-
8-13pH is alkali - have high concentration of OH-

Question 15

WHAT IS OPTIMUM TEMPERATURE

Answer 15

It is the temp where the rate of reaction is max, where the most ES complexes are formed.

Question 16

WHAT IS VMAX

Answer 16

The point where there’s a maximum rate of reaction/maximum enzymatic activity.
• When all the enzymes are attached to the substrate
• there’s a substrate saturation on active site

Question 17

WHAT OS SUBSTRATE SATURATION

Answer 17

The point where all of the substrates are occupied by enzymes

Question 18

WHAT IS THE TURN-OVER RATE

Answer 18

No. Of substrate molecules converted into products by enzyme per time unit

Question 19

WHAT IS THE KM VALUE

Answer 19

Concentration of substrate that produces half VMAX is referred as Michoelis Menton constant which is represented as KM.

Question 20

MICHAELIS-MENTON CONSTANT

Answer 20

• Half of the A.S. are occupied by the substrate
• The KM value indicates affinity of enzyme to it’s substrate
• The lower the KM value the higher the affinity
• KM is irreversibly proportionally with enzyme affinity to the substrate VMAX won’t be affected by KM

Question 21

ENZYME AFFINITY

Question 22

FACTORS AFFECTING THE KM VALUE

Answer 22

• Type of substrate
• Temperature ( works best at opt. Temp)
• pH value
• Presence of particular ions
• Presence is inhibitors ( decrease the enzymatic activity)