Chapter (5) Enzyme Activity

Question 1

Define the enzymes

Answer 1

Enzymes are type of proteins, that acts as a catalyst, to speed up the chemical reaction without being consumed in the reaction

Question 2

Why aren’t enzymes consumed?

Answer 2

Enzymes can perform their functions repeatedly functioning as workhorses (قوة عاملة) that carry out the processes of life.

Question 3

Are all enzymes type of proteins?

Answer 3

🎀 many but not all enzymes are proteins, because some RNA function as enzymes (ribozymes) 🎀

Question 4

💡 what are ribozymes?

Answer 4

• RNA molecules ‘
• they con accelerate chemical reactions.
• able to break & form covalent bonds within a nucleic acid molecule.
• ( 1 able of storing genetic information (like DNA)
  2 catalyzing specific biochemical reactions)

Question 5

In enzyme-catalyzed reactions, the reactant is called:

Answer 5

The substrate

Question 6

What is the substrate?

Answer 6

• The reactant in enzyme-catalyzed reactions ( the molecule that the enzyme is going to act on )

Question 7

What is the active site?

Answer 7

The active site is a special regions of the enzyme (pocket or groove on the surface of the enzyme) that is specifically shaped to fit the substrate

Question 8

What will happen when a substrate enter the active site?

Answer 8

When the substrate enters the active site, substrates combine with the active sites , to form temporary enzyme-substrate complex.

• • it forms a weak bond with the enzyme. **

Question 9

What do substrates form when they combine with enzymes?

Answer 9

• Enzyme-substrates complex.

Question 10

General information:

Answer 10

🧬🎀 Once the substrate is bound to the enzyme, the enzyme changes its shape slightly. This change in shape brings the reactive groups of the substrate closer together, making it easier for them to react. The enzyme also helps to stabilize the transition state of the reaction, which is the highest energy state of the reaction. This lowers the activation energy of the reaction, making it go faster.

🧬🎀 The product is released from the active site. Once the reaction is complete, the product is released from the active site. The enzyme then returns to its original shape and is ready to start the process over again.

Question 11

What do substrates form with enzymes when they are products 🔮🧸

Answer 11

Enzyme-product complex

Question 12

Describe the specifics of enzymes:

Answer 12

📖🩵* Each enzyme is specific for a certain reaction.

📖🩵* this specificity is a results of a unique amino acid sequence → which causes it to have a unique 3 D structure.

Question 13

What would affect enzyme’s activity or efficiency??

Answer 13

🍰 any physical or chemical factor that leads to a change in the shape or chemistry of the active site in the enzyme will interfere with the activity & efficiency of the enzyme🍰

Question 14

What will happen if the chemical / physical change on the enzyme was large enough??!

Answer 14

If the change is large enough, the enzyme will no longer function.

Question 15

What are the factors that determine the enzyme’s activity??

Answer 15

📚📚 Any physical or chemical factor that leads to a change in the shape or chemistry of the active site in the enzyme will interfere with the activity and efficiency of the enzyme.
📝🖍️ If the change is large enough, the enzyme will no longer function. 📚📚
🫧 salt concentration

☂️ pH

🫧 temperature

☂️ consentration of the enzyme and it’s substrate.

Question 16

Increased temperature may lead to:

Answer 16

Permanent denaturation of the enzyme.

Question 17

What is the function of catecholase??

Answer 17

Converts catechole (C6H4(OH)2) into benzoquinone (C6H4O2) and water (H2O) .

Question 18

What is the function of alpha-amylase enzyme?

Answer 18

•.• converts starch into the double sugar maltose.

Question 19

What is the function of the enzyme catalase??,

Answer 19

• Which decomposes hydrogen peroxide (H2O2,) into water & oxygen. *

Question 20

What is the other name of catecholase??

Answer 20

Catechole oxidase.

Question 21

👒💚 write the chemical formula of catecholase:

Answer 21

In the presence of catecholase, catechize is oxidized to form benzoquinone and water _-

Catechol + O2 →chatecholase→ benzoquinone + H20
🫶🏻⭐️

Question 22

What will happen when slicing apple?? (What causes browning)

Answer 22

🐙 when apple is sliced- –

🐙 catecholase will be released onto the white surface of the fruit.

🐙 and catalyzes the removal of electrons and hydrogens from catechol.
( catalyzing the catechize to react with oxygen)

🐙 as a result, Tue fruit will turn brown.

Question 23

🎨 can the rate of browning fruits be affected???

Answer 23

Simple changes in the conditions can change the rate of this chemical reaction.

Question 24

How temperature affect the activity of enzymes??

Answer 24

*📈❤️ As T increases the rate of the reaction will increase, too– but only up to a certain point-→ [ called the optimal temperature ] … after that increasing the temperature will cause the rate to drop sharply 🫧

• 🧸🤎 the reason why the rate drops sharply, is that because the protein can be desaturated, → so it loses it’s shape → so it’s to not going interact well with the substrate, → so the activity decreases.🩵

Question 25

🦜💚⭐️👒 how does amylase work?

Answer 25

👛 amylase is present in our saliva and begins to act on the starch in our food while still in the mouth.🧬

🩷🎀 Amylase changes starch into a simpler form: the sugar maltose (disacchraride) which is soluble in water. 🎀🩷

🖍️starch is broken down chemically while the mechanical breakdown of food in the mouth 🖍️

Question 26

How can I experimentally know that starch is digested to maltose??

Answer 26

🔆💛 first way :
⚗️ Benedict solution : it is a test reagent that reacts positively with simple reducing sugars like maltose , but will not react with starch ⚗️

🔆💛 second way :
⚗️Lugol’s solution : is a test reagent that reacts positively with starch but will not react with maltose⚗️

Question 27

Where can you find of catalase?

Answer 27

🧸🧸Catalase is an enzyme found in cells particularly in liver cells.

🧸🧸 catalase minimizes the accumulation of toxic hydrogen peroxide which is a product of several reactions that normally occur in cells.

🍰🤍( note that one of the functions of liver is breaking down poisonous substances (such as alcohol and drugs … ) so when hydrogen peroxide accumulates in the body .. it became toxic to the body.. so liver get rid of it because it contains catalase enzyme 🐙🫶🏻🎀🫧)

Question 28

Write the chemical formula of catalase :

Answer 28

2H2O2 →catalase → 2H2O + O2(bubbles 🫧)

Question 29

When we smashed the apple, it turned brown very quickly. Why?

Answer 29

🤍🤍 smashing the Apple will increase the surface area of the Apple that is exposed to the air , promoting the enzymatic oxidation reaction and accelerating the browning process 

We have smashed it by putting it in a mortar and smashed with a pestle

Question 30

What can you observe when you put an apple in 0° temperature and when you put an apple in 40° temperature which is very close to its optimal temperature

Answer 30

The apple that is in 0° temperature will take a very long time to turn brown, but the Apple envy 40° temperature turns brown faster than the first one because it is in its optimal temperature and enzyme is will work very well under its condition, and it will work faster and catalyze the call to react with oxygen faster than the apple that is put in 0° temperature because there the temperature is very low. The activity of enzyme is very low, so it will be very slow to turn brown. 

Question 31

What would you observe when you put an apple in a lemon juice and when you put one in distilled water?

Answer 31

The significantly influences, the activity of enzymes is PH optimum range is around 7.2 so when it is in distant water, it will work better than when it is in lemon juice so the apple in the water will. Turn brown faster than the apple and the lemon juice. 

Question 32

When preparing at test tube with amylase and starch .. if we performed the Benedict and loguls test.. once at zero time and the other after 40 minutes time what would you observe?

Answer 32

Add zero time when we perform the logos test it will turn to yellow color and it’s positive when you perform the Benedict test, the result will be negative. It will stay blue so the explanation for that is at zero time the enzyme had amylas had not acted yet, so the starch still starch and did not convert to Maltos, which is the reducing sugar that the Wicht should have reacted with. so it is still starch so the logo reacted with it and told us that there is some starch.

After 40 min time , the logol gave a negative result while Benedict gave a positive because the enzyme has reacted and converted the starch to maltose.

Question 33

What will happen in these three experiments?:

🧪 when you put a potato and water
🧪 when you put a potato and H2O2
🧪 boiled potato with H2O2

Answer 33

🧪🧪 the first experiment we will notice no reaction.
🧪🧪 in the second reaction we will see bubbles and this will indicate that there is a action action had happened because the potato has catechol enzyme in it .. which will be at with the hydrogen peroxide convert it to water and oxygen the oxygen we saw it as bubbles.

🧪🧪 in the third experiment, the chemical enzyme did not react with the H2O two because that the potato is boiled and increasing in temperature will lead to the permanent denaturation of the enzyme critical so it’s shape is not good anymore. It will not react with the substrate so it is damaged and will not react anymore but not no longer function.