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ENZYMES. http://www.kscience.co.uk/animations/model.swf. http://www.kscience.co.uk/animations/ectopeptidase.swf. http://www.kscience.co.uk/animations/enzyme.swf http://www.youtube.com/watch?v=XTUm-75-PL4.

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ENZYMES

http://www.kscience.co.uk/animations/model.swf

http://www.kscience.co.uk/animations/ectopeptidase.swf

http://www.kscience.co.uk/animations/enzyme.swf

http://www.youtube.com/watch?v=XTUm-75-PL4


In all metabolic activities of our body and cells, lots of small molecules called ENZYMES work.

If we destroy enzymes in the body, all reactions will slow down and stop.

Because enzymes reduce activation energy of the reactions.

The minimum amount of energy that is needed to start the reaction is called ‘ ACTIVATION ENERGY ’


Substance which is used to decrease the activation energy of a reaction is called ‘ CATALYSTS ’ . Enzyme is a catalyst which is found in living organisms ; It REDUCES the activation energy and makes reaction FAST and EASY


Heat can also decrease activation energy, but in cells heat can harm/denature molecules, so instead of heat enzymes speed up reactions.

Usually they are named as:

Enzyme that breaks down sucrose : SUCRASE

Enzyme that breaks down lipid : LIPASE

Sometimes they have special names .

For example : The enzyme that breaks down starch is called amylase.

-ase


STRUCTURE OF ENZYMES can harm/denature molecules, so instead of heat enzymes speed up reactions.

  • Enzymes are PROTEINS. Enzyme synthesis is controlled by DNA (genes)

  • But in most enzymes protein part joins with other molecules. (SIMPLE AND COMPLEX ENZYMES)


COFACTOR can harm/denature molecules, so instead of heat enzymes speed up reactions.( mineral )

Activated enzymeAPOENZYME + or

( HOLOENZYME ) COENZYME( vitamin )

1. Enzymes acts on their SUBSTRATES. A SUBSTRATE is the molecule that is affected by enzymes.

Enzyme+Substrate→ Enzyme-Substrate Complex → Enzyme + Products


substrate can harm/denature molecules, so instead of heat enzymes speed up reactions.

c.

Active site

b.

Apoenzyme

a.

Enzyme-subtrate complex

d.

Products

f.

Enzyme-subtrate complex

e.


Properties of enzymes: can harm/denature molecules, so instead of heat enzymes speed up reactions.

1. Each enzyme has a specific substrate .

2. The site that binds to substrate is called as ACTIVE SITE . The relation between an enzyme and its substrate is called LOCK AND KEY MODEL

3. The enzyme isn’t SPENT during reaction(only used), So it can be used MANY TIMES. (never changed)


4. Reactions of Enzymes are Reversible.(not digestive ones) can harm/denature molecules, so instead of heat enzymes speed up reactions.

Starch+ amylase enzymeglucose+ enzyme

5. Enzymes can’t work unless being water less than %15

6. Enzymes can work as a team. (ex.in digestion)

7. Enzymes are produced inside the cell but they can work inside OR outside of the cell.

8.Enzymes start their action from the outer surface of the substrate.


1 temperature
1.TEMPERATURE : can harm/denature molecules, so instead of heat enzymes speed up reactions.

At lower temperature ;the reactions slows down or stops but as the temperature increases the rate of the reaction increases until optimum. But denatures after 60 C.

The factors that affect enzyme activity


2.pH : can harm/denature molecules, so instead of heat enzymes speed up reactions.

Each enzyme works best at a certain pH ,that is called optimum pH.

( Ex: Optimum pH=2 in the stomach for digestion )

Enzymes are (denatured) broken down above or below the optimal pH.

1 2 3


3 water
3. WATER can harm/denature molecules, so instead of heat enzymes speed up reactions.

Enzymes can’t work unless being water less than %15.

Ex : Dry plant seeds can’t germinate


4 concentration of enzyme
4.CONCENTRATION OF ENZYME can harm/denature molecules, so instead of heat enzymes speed up reactions.

Increasing the enzyme concentration increases the rate of reaction.

But after all substrate molecules are used and no change will be in the rate of reaction


5 concentration of substrate
5.CONCENTRATION OF SUBSTRATE can harm/denature molecules, so instead of heat enzymes speed up reactions.

If we increase the concentration of substrate, the rate of the reaction increases. But after all enzyme molecules are full, they can not change the rate of reaction.


6 surface area of the substrate
6. SURFACE AREA OF THE SUBSTRATE can harm/denature molecules, so instead of heat enzymes speed up reactions.

increasing the surface area of substrate,increases the activity of enzymes

Substrate surface


For example ; if we cut meat into pieces to make the surface bigger. Minced meat is digested easier than a piece of meat.

Enzyme activity


6 inhibitors
6.INHIBITORS surface bigger. Minced meat is digested easier than a piece of meat.

Some chemicals like Mercury (Hg) slows or completely stops the activity of enzymes . These molecules are inhibitors .

Reaction rate

Enzyme

Enzyme+

inhibitor


7 activators
7.ACTIVATORS surface bigger. Minced meat is digested easier than a piece of meat.

Some chemicals increase the activity of enzyme and they are called activators

Rate of the reaction

With Activator

Without activator


I surface bigger. Minced meat is digested easier than a piece of meat.

K + M N + O + M

II

By looking at the reaction above, answer the questions.

a. What kind of a reaction is I and II ?

b. Which of them is the enzyme?WHY?

c. Which of them is the product and substrate?


Fresh liver Liver grounded Liver boiled surface bigger. Minced meat is digested easier than a piece of meat.

pieces in mortar in water

2 ml of H202 solution is placed in each tube. Fresh , grounded and boiled liver are placed in the tubes as shown in the figure.

a. Write the reaction of equation?

b. Write the correct order of reaction rates from the fastest to the slowest ?

Explain the reasons

H202

H202

H202


  • Enzyme 1 Enzyme 2 Enzyme 3 surface bigger. Minced meat is digested easier than a piece of meat.

  • X Y Z M

  • As you see in the above reaction, some chemical reactions can ocur in chains. They follow each other. What is the advantage of this working together?

  • Reactions can be reversible(occur in BOTH ways)

  • Activation energy is lowered

  • Reaction speeds up

  • Types of products increases

  • Amount of substrate used is reduced. (decreases)


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