Enzymes

Chapter 7

What is metabolism?

The sum of all of the chemical reactions taking place in a cell or organism

What do all reactions in the cell do?

Either produce or use energy

Where does almost all energy required by cells come from?

Directly or indirectly from the sun

What do plants use to produce glucose and oxygen from carbon dioxide and water during photosynthesis?

Light energy from the sun and the green pigment chlorophyll

What do plants do with glucose?

Used by the cell immediately in cellular respiration to produce ATP

Be converted into many other compounds needed by the plant. Some of these are used to build new tissue and any excess is stored for future use

What are typical products of when animals digest plant material?

Glucose and amino acids

What do animals do with glucose?

It gets repaired by cells to produce ATP to supply their immediate energy needs

What do animals do excess glucose?

Leftover glucose can be converted into glycogen and stored

What do animals do with amino acids obtained from plants?

They get joined together to form animal proteins and build muscle and bone

What do animals do with excess amino acids?

They cannot be stored and are broken down to urea and secreted in urine by the kidneys

What is the food chain in regards to solar energy?

The energy collected initially by plants using solar energy to fuel photosynthesis gets passed along the food chain as chemical energy once plants are eaten by herbivores, who in turn are eaten by carnivores, who digest them and extract the energy and materials that they use to build their own bodies

What organisms obtain energy outside of the food chain without solar energy and photosynthesis as the starting point?

Prokaryotic microorganisms that obtain energy from chemosynthesis

What are enzymes made of?

Proteins made up of long chains of amino acids joined together by peptide bonds. These chains are folded into a complex 3D shape

What are enzymes?

Biological catalysts that speed up chemical reactions without being used up in the process

Can enzymes be reused?

Yes

What are co-enzymes?

Helper chemicals that attach to some enzymes to let them work properly

What are co-enzymes made of?

Organic and non-protein

What vitamins can act as co-enzymes?

B1 and B6

What factors effect enzyme activity?

Temperature, pH, enzyme concentration, substrate concentration, inhibitors

How does pH affect enzyme activity?

Different enzymes work best within certain narrow pH ranges. Most work the best around neutral

What is an example of an enzyme that works best at a pH of 7?

Amylase

What is an example of an enzyme that works best at a pH of 2?

Pepsin

What is an example of an enzyme that works best at a pH of 10?

Lipase

How does temperature affect enzyme activity?

Enzyme activity increases with temperature, up to about 40°C. Above 40°C, enzymes start to rapidly denature and don’t work

What is the optimum temperature of plant enzymes?

25°C

What happens to the enzymes in your body if your temperature gets too high?

The enzymes all over your body start to denature, causing problems particularly in sensitive areas of your body, such as the brain, which can result in seizures

What does it mean if an enzyme has become denatured?

It has lost its shape and therefore it’s activity

What are the three main causes of an enzyme becoming denatured?

Temperatures above 40°C, change in pH and agitation

How do temperatures above 40°C cause an enzyme to become denatured?

The enzyme begins to melt. If the temperature rises and stops before 50°C the enzyme can resume its shape and activity of the temperature drops again. If the temperature goes above 50°C the change is irreversible

What is an example of how a change in pH cause enzymes to become denatured?

Salivary amylase acts on starch on the mouth and begins the process of breaking it down into fructose. It’s optimum pH is 7-8, which is what is found in the mouth. Once the food reaches the stomach, the pH suddenly changes to pH 1, denaturing the salivary amylase and stopping carbohydrate digestion

What does agitation mean?

Shaking or beating

What is an example of how agitation denatures enzymes?

When egg whites are beaten with sugar, the albumen is denatured to form microscopically small strands of solid protein that trap and bind the sugar. This makes it thick and viscous so that it can be shaped

What is the active site of an enzyme?

The place in the enzyme where it’s substrate fits and where the reaction takes place

How many types of substrate can fit into the active site of an enzyme

Only one specific substrate

What happens when the substrate engages with the active site of an enzyme?

The shape of the substrate changes slightly, and in many cases, so does the shape of the enzyme

What is the combination of the enzyme and substrate called?

The enzyme-substrate complex

What do the changes in shape of the substrate and enzyme do?

Makes it easier for the products to form, lowers the activation energy

What do the products form with the enzyme?

The enzyme-products complex

What happens to the enzyme when the products are ejected?

It retains its original shape and becomes free to collect a fresh substrate molecule

What is it called when the product is more complex than the reactants?

An anabolic reaction

Why is it called if the products are smaller and less complex than the reactants?

A catabolic reaction

What is bioprocessing?

The use of living organisms to or their products to produce useful substances

What is a bioreactor?

A vessel in which cells or organisms make products

What are the two bioprocessing methods?

Batch and continuous

How does batch processing work?

Raw materials and immobilised enzymes or their sources are placed in the bioreactor and allowed to react. When the reaction is complete, the products are removed, separated and purified. The bioreactor is then cleaned and another batch is prepared

What is made via batch processing?

Medicines, vaccines, antibiotics, clotting agents, insulin, growth hormones, etc.

What are the advantages of batch processing?

It allows greater quality control, and if something goes wrong, damage limitation is easier

How does continuous processing work?

Raw materials are fed in at one end and the product comes out the other over a long period of time

What is an example of something made using continuous processing?

Alcohol

What is an advantage of continuous processing?

It is more efficient and quicker

What is a disadvantage of continuous processing?

If a problem arises, it can be harder to identify when it started, so the process needs continuous monitoring

What are immobilised enzymes?

The enzymes are trapped in a gel or fixed to each other

What are the four main advantages of enzyme immobilisation?

The enzyme can be reused so only small amounts are needed

The enzyme is easier to recover so it can be used again

It is easier to purify the product as there is one less thing to remove

It makes the enzymes last longer, making the process more economical

How is immobilised yeast used?

It produces the enzyme zymase to convert sugars, including glucose (substrate) to alcohol (product)

How is immobilised glucose isomerise used?

Converts glucose (substrate) to fructose (product). This is much used in the confectionary industry

How is immobilised invertase used?

It converts sucrose or cane sugar (substrate) to fructose and glucose (product). This is sold as golden syrup

How do washing powders use immobilised enzymes?

Biological washing powders contain enzymes that digest proteins (proteases) and lipids (lipases). These are very effective at stain removal

What does the enzyme catalase do?

Breaks down hydrogen peroxide into hydrogen and oxygen

What food can catalase be found in?

Potatoes

What does the enzyme protease do?

Breaks down protein

What food can protease be found in?

Papayas

What does the enzyme amylase do?

Breaks down starch into sugars, such a as glucose and maltose

Why food can amylase be found in?

Bananas

What does the enzyme lipase do?

Breaks down lipids

What food can lipase be found in?

Avocados

What does the enzyme pepsin do?

Digests proteins

What is the product of amylase?

Maltose

What are the products of lipase?

Fatty acids and glycerol

What are the products of protease?

Amino acids, or polypeptides

What are the products of catalase?

Water and oxygen