Enzymes

What are the features of enzymes?

\-made of protein

\-work because they have the correct shape to fit the substrate

\-reactions are reversible like a lock in a key

\-Involved in anabolic and catabolic reactions

Which is the substrate, prod and enzyme in the reaction in the mouth?

Starch(substrate)→maltose (product)

\-amylase (enzyme)

\
Amylase is an enzyme that breakdown starch down into maltose

Name 3 anabolic enzymes and their uses

\-DNA ligase: used in genetically engineering to join two pieces of DNA together

\-DNA polymerase: found in plants and animals that forms and repairing DNA

\-Enzymes involved in photosynthesis(water and CO2 into glucose)

What main factors affect enzyme activity?

Temperature and pH affect the rate of reaction of enzymes

Enzyme temperature

\-In the body work best at 37.5°C

\-In plants best at 20-30°C

\-Enzymes cannot function at very low temperatures

\-Above a certain temp enzymes behind to loose their shape and become denatured

Enzyme pH

\-Human enzymes only work at a very narrow pH range (6-8)

\-Optimal pH for enzymes is neutral

\-An exception is pepsin: a digestive enzyme in the stomach that works in acidic conditions

Plant vs human enzyme under temp

Plant vs human enzyme under pH

What are Inhibitors?

* Inhibitors attach to enzymes and destroy their shape
* When this happens enzymes are said to be denatured

Bioprocessing

\-the use of enzyme controlled reactions to produce a product using microorganisms

\-Recently used for antibiotics, drugs and vaccines

\-Enzymes in bioprocessing are often reused to prevent waste

\-This is due to immmobilising them

\-Bioreactors are vessels where living cells are used to create products

Why is the metabolism important?

Maintain homeostasis

Cellular Energy

Energy stored in the bonds of biomolecules-respiration

Where is chemical energy stored in the cells?

Energy is stored in bonds of biomolecules and is transferred to consumers when they eat producers.

When do organisms break down energy-rich molecules?

During respiration

What is a catalyst?

A catalyst speeds up a reaction without being used up

\-enzyme is a biological catalyst made if protein

Define an enzyme

A protein that speeds up or slows down a chemical reaction without being used up in the reaction

What are enzymes made of?

Enzymes are made of chains of amino acids which are then folded into a 3-D shape.

Enzymes work because they have the 3-D shape to fit a particular molecule

They will neatly fit into the substrate.

What is specificity?

Enzymes work because they have the 3-D shape to fit a particular molecule

They will neatly fit into the substrate because they are the same shape

What is a substrate?

The substance with which the enzyme reacts

Enzyme reactions

Anabolic or catabolic

Reversible like a key in a lock

What is the active site of an enzyme?

The part of the enzyme that combines with the substrate

In the enzyme rate of reaction experiments, what enzyme was used?

catalase found in celery

What solutions were used?

\-20 ml of pH buffer

\-a drop of washing up liquid

\-2 ml of hydrogen peroxide

How is the rate of reaction recorded?

By recording the volume of foam produced at different temperatures, pH levels etc.

Define immobilised enzymes

Enzymes that are attached to or fixed to each other or to an inert material

Active Site

The part of the enzyme that combines with the substrate

What are the benefits of immobilised enzymes?

\-they may be reused

\-easy to separate from the product

\-cheaper

Uses of immobilised enzymes

\-produce fructose from glucose

\-convert penicillin to different forms

\-produce sweet tasting sugars from lactose

Describe the structure of enzymes

\-folded, globular, 3D shape

Describe the shape of the active site

\-the active site is not a rigid shape that is fixed to the substrate

\-when the substrate enters the active site, it changes the enzyme shape slightly.

\-enzyme fits more percisely

What is meant by the term ‘specificity’ in relation to enzyme activity?

An enzyme can only work on one certain substrate

What happens to the activity of enzymes when they are placed in a medium outside of their optimum pH?

Reduction of activity due to denaturation/shape change

Substances used in immobilisation

1. sodium alginate
2. calcium chloride

Benedict solution is used to detect

reducing sugars

Name a mineral essential in plants and its function

1. magnesium
2. chlorophyll production

What is the substrate of catalase?

hydrogen peroxide

How is enzyme activity measured in the experiment?

volume of foam produced/minute

State a metabolic function of proteins

enzymes

Where are phospholipids located?

Membrane

What does NAD stand for?

Nicotinamide adenine dinucleotide

What subatomic particles are transferred by NAD?

protons and electrons

Why are buffers needed when carrying out experiments?

Keep pH constant, or if desired vary pH

What enzyme works on lipids?

lipase

What are the products when lipase works on lipids?

1. fatty acids
2. glycerol

Describe what happens when a substrate comes into contact with an enzyme

1. Enzyme and a certain substrate come together (specificity\`)
2. The substrate fits snugly in the active site, since the active site does not have a rigid shape (Induced Fit model)
3. The enzyme and substrate as one is called the Enzyme-Substrate Complex
4. The products are formed
5. The enzymes shape is unchanged

Why are enzymes used in washing-up powders?

To get rid of food stains

Describe a denaturation experiment that you conducted in the laboratory.

__-substrate__: hydrogen peroxide

__-enzyme__: catalase (from celery)

\

1. Boil 5g chopped celery in a water bath
2. Use the unheated chopped celery as a control
3. Place both in water bath
4. Add hydrogen peroxide
5. No activity in denatured enzyme
6. Record volume of foam produced
7. Measure the result of the control
8. Compare the results
9. pH and temperature were maintained constant

What does ADP stand for?

Adenosine Diphosphate

\-base adenine, 5 carbon sugar (ribose), 2 phosphate groups

\-low energy molecule

What does ATP stand for?

Adenosine Triphosphate

-if another phosphate is added to ADP

-extra energy, since extra bond

-rich energy molecule

-stores and carries energy around cell

Addition of a phosphate to a bond

Phosphorylation

What is the chemical nature of enzymes?

proteins

Comment on the molecular shape of enzymes?

3D folded globular shape

Bioreactor

Vessel in which living things are used to create products or

A vessel used to carry out enzyme controlled reactions.

Bioprocessing

Use of enzyme-controlled reactions to produce a product

In which organelle are enzymes produced?

they are proteins- ribosomes

Give an example of the use of immobilised enzymes in a bioreactor. State:


1. Enzyme
2. Substrate


3. Product
4. Application

1. Enzyme: Sucrase
2. Substrate: Sucrose


3. Product: Glucose
4. Application: sweetener

What is the optimum pH for enzymes?

7-9 pH

Give an example of an anabolic reaction

protein synthesis, DNA synthesis

Explain enzyme specificity with reference to the active site

Specificity means that enzymes can act on certain substrates. This means that only one substrate fits the shape of an active site

Name two processes that occur in plant or animal cells that require the use of enzymes

When immobilising an enzyme, you used a gel substance to trap the enzyme. A second substance was also used to make gel insoluble. Name first and second substance

1. Gel- sodium alginate

2. second substance- calcium chloride

In relation to investigation into heat denaturation of an enzyme, name the products formed

oxygen and water

What is adsorption

When enzymes are physically attached to inactive supports

Name two processes that occur in plant or animal cells that require the use of enzymes

• Plants = Respiration and photosynthesis

• Animals = Respiration and DNA replication

Some biological washing powders contain enzymes similar to the ones found in our digestive system. Many of these enzymes are extracted from bacteria. Why is 40°C the recommended temperature for these washing powders?

40°C is these enzymes' optimum temperature

Write notes on metabolism

Metabolism is the sum of all chemical reactions that take place within an organism.
2. It is controlled by enzymes.
3. Catabolic and anabolic enzymes are involved in metabolism.
4.a) A catabolic enzyme is amylase which converts starch into maltose.
4.b) It is catabolic because it breaks down a substance into simpler parts.
5.a) An anabolic enzyme is DNA ligase which is used in genetic engineering.
5.b) It is an anabolic enzyme because it converts simpler molecules into a more complex form.

Write notes on ADP

1. ADP stands for adenosine diphosphate.
2. It is a low energy molecule.
3. It is found in the cells of all organisms.
4. ADP + P ——> ATP
5. ADP + energy ——> ATP + water

“Enzymes are essential for metabolism” Explain why this statement is true

Enzymes are biological catalysts and they control the rate of metabolic reactions

State one way by which an enzyme may be denatured

high temp, too low or too high pH

Give two features of a denatured enzyme

• change of shape

• loss of function

Give an example of a reducing sugar

glucose/maltose