1.7 Enzymes

Question 1

What are enzymes?

Answer 1

Enzymes are proteins that act as biological catalysts by accelerating chemical reactions.

Question 2

How many different enzymes are typically found in a living cell?

Answer 2

About 4000 enzymes

Question 3

What is a catalyst?

Answer 3

A substance that speeds up a reaction without being consumed; in biological systems, enzymes act as catalysts.

Question 4

What is the active site of an enzyme?

Answer 4

The location where the substrate binds, usually a pocket or groove formed by the enzyme’s tertiary structure.

Question 5

Describe the lock-and-key method

Answer 5

A model explaining how specific substrates (keys) fit into specific enzymes (locks) for catalysis.

Question 6

What is the induced-fit method

Answer 6

Instead of the enzyme’s active site being a perfect fit for the substrate from the start, the enzyme changes its shape slightly when the substrate binds. This adjustment helps the enzyme bind more tightly and increases the enzyme’s range of specificity, allowing it to interact with multiple substrates. As a result, one enzyme can work on a variety of substrates, making it more versatile.

Question 7

What is the enzyme-substrate complex?

Answer 7

The temporary complex formed when an enzyme binds to its substrate(s) before converting them into products.

Question 8

What are cofactors?

Answer 8

Non-protein groups, often metals, that bind to enzymes and are essential for their catalytic activity.

Question 9

What are coenzymes?

Answer 9

Organic helpers, usually from vitamins, that assist enzymes.

Question 10

What factors affect how enzymes work?

Answer 10

Substrate concentration, temperature, and pH (acidity).

Question 11

What is competitive inhibition?

Answer 11

When an inhibitor with a structure similar to the substrate occupies the active site, stopping the substrate from binding. The effect can be reversed by increasing substrate concentration

Question 12

What is noncompetitive inhibition?

Answer 12

The inhibitor does not have a structure like the substrate, and it binds to another part of the enzyme. It changes the shape of the enzyme and active site so that the substrate cannot fit the altered active site. No reaction occurs, and the effect cannot be reversed by adding substrate/increasing substrate concentration.

Question 13

What is allosteric regulation?

Answer 13

A method used by cells to control enzyme activity. Is it when a molecule binds to an enzyme and changes its shape, affecting its activity

Question 14

What can happen if an enzyme is missing or defective?

Answer 14

It can lead to serious problems, like metabolic disorders, where the body can’t break down certain substances. For example, a missing enzyme in lactose intolerance prevents proper digestion of lactose, causing symptoms like bloating and cramps.

Question 14

What is feedback inhibition?

Answer 14

A way to control reactions where the end product stops an earlier step from happening if there’s too much

Question 15

Give an example of feedback inhibition

Answer 15

Isoleucine can stop the enzyme that makes it when there’s enough of it

Question 16

What does the enzyme lipase do?

Answer 16

It helps break down lipids (fats) into smaller parts.

Question 17

What reaction does sucrase catalyze?

Answer 17

It breaks down sucrose (sugar) into glucose and fructose.

Question 18

What is enzyme specificity?

Answer 18

Each enzyme only works with a specific substrate or a group of similar substrates.

Question 19

How do temperature changes affect enzymes?

Answer 19

Too high or too low temperatures can change an enzyme’s shape, making it less effective.

Question 19

Why do enzymes have a unique shape?

Answer 19

Their shape determines which substrate they can bind to and what reaction they can speed up.

Question 20

What happens to enzyme activity if the pH level changes too much?

Answer 20

Enzymes have an optimal pH for maximum activity. Extreme pH levels can denature (change the shape of) the enzyme, reducing its activity.

Question 21

How can the concentration of substrate affect enzyme activity?

Answer 21

More substrate can increase the reaction rate until the enzyme is saturated.

Question 22

What is saturation level in enzyme reactions?

Answer 22

The point where all enzyme active sites are occupied by substrate, and adding more substrate doesn’t increase the reaction rate.

Question 23

What is an example of an enzyme with a low pH optimum?

Answer 23

Pepsin, which works best at a pH of 1.5 in the stomach

Question 23

What role do antibiotics play regarding enzymes in bacteria?

Answer 23

They often inhibit bacterial enzymes, preventing bacteria from growing.

Question 23

What is irreversible inhibition?

Answer 23

It’s when an inhibitor permanently attaches to an enzyme, stopping it from working. This type of inhibition is called noncompetitive inhibition because it changes the enzyme’s shape, so the substrate can’t react with it anymore.

Question 23

When an inhibitor permanently binds to an enzyme, stopping it from working.

Answer 23

Cyanide is a toxic irreversible inhibitor. It binds to an enzyme needed for cellular respiration, preventing cells from using oxygen. This is dangerous because it stops energy production in cells, which can be fatal.

Question 23

What is the typical pH optimum for most enzymes?

Answer 23

Around 7, which is close to the pH of cellular contents.

Question 24

What is denaturation in enzymes?

Answer 24

It’s when the enzyme’s structure unravels due to high temperatures, causing it to lose function.

Question 24

How do enzymes from organisms in cold regions differ?

Answer 24

They have lower temperature optima, functioning best near 0°C. This allows them to maintain activity in cold environments where other enzymes might be inactive, ensuring essential biological processes continue despite low temperatures.

Question 24

What is an example of an enzyme with a high pH optimum?

Answer 24

Trypsin, which operates best at about pH 8 in the intestine

Question 24

How does temperature affect enzyme activity?

Answer 24

Generally, as temperature increases, reaction rates increase until enzymes begin to denature.

Question 24

What is the typical temperature range for peak enzyme activity?

Answer 24

Between 40°C and 50°C, where kinetic motion is high but denaturation hasn’t occurred.

Question 24

What is lactose intolerance?

Answer 24

A condition where individuals do not produce enough lactase, leading to symptoms like nausea and cramps after consuming lactose.

Question 24

How do enzymes improve laundry detergents?

Answer 24

They help remove stains better at lower temperatures and with less scrubbing. They are a mix of proteases (for proteins), lipases (for fats), and amylases (for starches).

Question 24

What is lactase?

Answer 24

An enzyme that breaks down lactose into glucose and galactose, important for digestion in individuals without lactose intolerance.

Question 24

What happens to enzyme activity above 60°C?

Answer 24

The activity drops to zero as the enzyme denatures.

Question 24

What happens to digestion without sufficient water?

Answer 24

Improper temperature and pH lead to inefficient digestion, impaired nutrient absorption, and affected waste removal, potentially causing discomfort and health issues.

Question 25

What role does water play in enzymatic reactions during digestion?

Answer 25

Water is involved in hydrolysis, which is necessary for breaking down complex molecules into simpler forms.

Question 25

Why is water necessary for digestion?

Answer 25

Water acts as a solvent, helping to break down food, transport nutrients, and facilitate enzymatic reactions.

Question 25

Why is it important for the human body to maintain a proper temperature?

Answer 25

Proper temperature ensures enzyme activity, metabolic processes, and overall bodily functions work efficiently at 37°C

Question 26

What enzymes are in contact lens solution?

Answer 26

Proteases and lipases are added to get rid of dirt

Question 27

What enzymes are in meat tenderdiser?

Answer 27

Protease can be added to tough cuts of meat to make it more tender

Question 27

What are some uses of enzymes in industry?

Answer 27

Enzymes have many industrial and commercial uses, including in food production, cleaning products, and biofuels.

Question 28

What are inhibitors?

Answer 28

Inhibitors are substances that decrease or block enzyme activity by binding to the enzyme, either at the active site (competitive inhibitors) or at another site (noncompetitive inhibitors).