2007

WHAT IS MEANT BY IMMOBILISATION?

Means fixed in place. Immobilised enzymes are enzymes that are attached,or fixed to each other or to an inert material.

NAME A SUBSTANCE THAT IS USED TO IMMOBILISE ENZYMES?

Sodium Alginate

2 ADVANTAGES OF IMMOBILISING ENZYMES?

  • Can be reused. This is a huge advantage as the cost of replacing enzymes are very high.
  • The process of immobilising an enzyme increases its stability

ONE APPLICATION OF A NAMED IMMOBILISED ENZYME - REFER TO SUBSTRATE, PRODUCT & ENZYME.

Lactase is an immobilised enzyme in porous beads and used to convert lactose into sweeter tasting sugars- glucose and galactose. These products are then used to replace condensed milk in the manufacture of soft toffee and caramel.

WHAT IS MEANT BY AN ENZYME?

A protein catalyst. It alters the rate of a reaction without being used up or permanently changed in the reaction. 

EXPERIMENT ON THE EFFECT OF TEMPERATURE ON THE ENZYME.

  1. NAME ENZYME USED: Catalase
  2. NAME THE SUBSTRATE: Hydrogen Peroxide
  3. NAME ONE FACTOR YOU KEPT CONSTANT: ph
  4. HOW ?: By using a buffer
  5. HOW DID YOU VARY THE TEMPERATURE: By using a water bath and hot plate. 3 different water baths were set up all at different temperatures.
  6. HOW DID YOU MEASURE THE RATE OF ACTIVITY OF THE ENZYME?

By recording the amount of foam produced in three minutes in each of the different temperatures.

     (G)WHAT WAS THE RESULT OF YOUR INVESTIGATION: at around 40 degrees enzyme action is the fastest. This is the optimum temperature. As the temperature increases, enzyme action decreases and finally stops as the enzyme is denatured.

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2008 

WHAT IS MEANT BY THE ENZYME’S OPTIMUM PH?

This is the ph at which the enzyme works best at.

WHAT IS A DENATURED ENZYME?

This is when the structure of an enzyme is permanently changed and it can no longer function. This is caused by the high temperature of unsuitable ph.

IN THE COURSE OF YOUR STUDIES YOU INVESTIGATED THE EFFECT OF DENATURATION BY HEAT APPLICATION ON THE ACTIVITY OF AN ENZYME.

  1. NAME THE ENZYME THAT YOU USED: catalase
  2. WHAT SUBSTRATE DID YOU USE: hydrogen Peroxide
  3. DESCRIBE HOW YOU CARRIED OUT THE INVESTIGATION: 1. Boil 5g of chopped celery at 100C for 10 minutes to denature it. Leave it to cool. 2. Add 200ml of buffer pH 9 into two graduated cylinders. 3. Add one drop of washing up liquid to each graduated cylinder. 4.Add 5g of boiled celery to one and label A. Add 5g of un-boiled celery to the other graduated cylinder and label B. This is control. Add 5ml of Hydrogen peroxide to both graduated cylinders. Place both tubes in a water bath at 25C. Measure the amount of foam produced in 3 minutes.
  4. STATE RESULTS THAT YOU OBTAINED: The boiled catalase produced no foam and the unboiled catalase produced foam.

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2009 

TO WHICH GROUP OF BIOMOLECULES DO THE ENZYMES BELONG? 

Proteins 

NAME A FACTOR THAT INFLUENCES THE ACTIVITY OF AN ENZYME?

Ph / temperature

DESCRIBE HOW YOU CARRIED OUT THE IMMOBILISATION: 

Mix yeast with sodium alginate in a beaker using a glass rod. Draw the mixture into a syringe. Release the mixture drop by drop in a calcium chloride solution to form gel beads. Leave the beads harden. Filter beads and wash with distilled water.

DRAW A LABELLED DIAGRAM OF THE APPARATUS USED TO INVESTIGATE THE ACTIVITY OF THE IMMOBILISED ENZYME.

BRIEFLY OUTLINE HOW YOU USED THE APPARATUS REFERRED TO ABOVE:

Pour the beads of the immobilised enzyme in a separating funnel. A short piece of drinking straw to prevent beads from blocking funnel. Add some yeast to the water in a beaker and stir. Pour this solution into a second separating funnel. Dissolve some sucrose in warm water. Pour half of the sucrose solution into each funnel. Test products by letting them drip onto glucose test strips - clinistix. Note and record the time taken for glucose to first from. Observe products.

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2010

WHAT IS AN ENZYME?  A protein catalyst that alters the rate of a reaction without being used up or permanently changed in the process.

WHAT IS MEANT BY THE SPECIFICITY OF AN ENZYME?

Each enzyme can only act on a particular substrate. E.g Amylase acts on starch.

EXPLAIN HOW THE ACTIVE SITE THEORY MAY BE USED TO EXPLAIN THE SPECIFICITY OF ENZYMES.

  • The substrate binds with the active site of the matching enzyme.
  • An enzyme-substrate complex is formed.
  • The enzyme changes shape to fit better around the substrate- the induced fit action
  • The substrate is converted into the product 
  • The product leaves the active site of the enzyme
  • The enzyme returns back to the original shape and can work again

WHAT DOES THE TERM IMMOBILISATION REFER TO WHEN USED ABOUT ENZYMES.

Immobilised enzymes are fixed, attached to each other or an  inert material so that they are not free in the solution

EXPLAIN THE TERM BIOREACTOR

A vessel or container which living cells or their products are used to make a product.

GIVE ONE EXAMPLE OF IMMOBILISED ENZYMES IN BIOREACTORS.

Lactase is an immobilised enzyme in porous beads and used to convert lactose into sweeter tasting sugars- glucose and galactose. These products are then used to replace condensed milk in the manufacture of soft toffee and caramel.

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2011 

WHAT IS MEANT BY THE TERM METABOLISM.

Metabolism refers to the chemical reactions that occur in the cells of organisms.

“ENZYMES ARE ESSENTIAL FOR METABOLISM”.EXPLAIN WHY STATEMENT IS TRUE.

Enzymes are protein catalysts. Metabolic reactions are controlled by enzymes.

{They work by speeding up the cell’s chemical reactions by lowering the free energy of activation.(They reduce the energy needed for the chemical reactions to take place)}

STATE ONE WAY IN WHICH AN ENZYME CAN BE DENATURED.

High temperature /unsuitable pH

TWO FEATURES OF A DENATURED ENZYME

  • Changed structure
  • Loss of function

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2012

WHAT IS THEIR CHEMICAL NATURE

Protein

COMMENT ON THEIR SHAPE

3D and folded

EFFECT OF TEMPERATURE ON THE RATE OF ENZYME ACTION

  1. NAME THE ENZYME USED: catalase
  2. NAME SUBSTRATE: Hydrogen peroxide
  3. WHY IS IT NECESSARY TO KEEP PH CONSTANT: So there is only one variable and to eliminate the possible influence on the rate
  4. HOW DID YOU KEEP PH CONSTANT: Buffer
  5. HOW DID YOU VARY TEMPERATURE: Water baths at different temperatures.
  6. HOW DID YOU KNOW ENZYME WAS WORKING: foam was produced
  7. DRAW A GRAPH:

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2013

WHAT IS THE TERM USED FOR SUBSTRATE(S) THAT RESULT FROM THE ACTION OF AN ENZYME ON ITS SUBSTRATE.

Products

EXPLAIN TERM OPTIMUM ACTIVITY? 

The enzyme is working at its maximum rate 

DRAW A GRAPH OF RESULTS OBTAINED (HEAT DENATURATION)

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2014 

NAME TWO PROCESSES THAT OCCUR IN PLANTS OR ANIMAL CELLS THAT REQUIRE THE USE OF ENZYMES

  • Digestion
  • Respiration
  • photosynthesis

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2016 

DESCRIBE HOW YOU ADDED A VERY SMALL AMOUNT OF VOLUME OF A SOLUTION

dropper/Pipette/Syringe

NAME THE GEL SUBSTANCE YOU USED TO TRAP THE ENZYME 

Sodium Alginate

NAME SECOND SUBSTANCE YOU USED TO MAKE GEL INSOLUBLE 

Calcium chloride

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2017

EXPLAIN WHY CHANGING THE PH WOULD HAVE AN EFFECT ON ENZYME ACTIVITY

Changing the pH would make the active site more acidic or more alkaline,this would change the shape of the active site and the substrate would no longer fit.

GRAPH ON THE EFFECT OF PH ON ENZYME ACTIVITY 

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2018

WHAT HAPPENS TO THE ACTIVITY OF ENZYMES WHEN THEY ARE PLACED IN A MEDIUM OUTSIDE OF THEIR OPTIMUM PH. EXPLAIN

The activity is reduced. The shape of the active site has changed/ denatured.