Topic 2.3

Question 1

What is an endocrine gland?

Answer 1

Endocrine glands secrete substances directly into the blood.

Question 2

What is an exocrine gland?

Answer 2

Exocrine glands secrete substances into a duct. The duct then carries the substances where they are needed.

Question 3

What is the lock and key hypothesis?

Answer 3

• The idea that a molecule with a complementary shape can bind with the active site.

Question 4

What is the enzyme-substrate complex?

Answer 4

When the substrate binds with the active site of the enzyme.

Question 5

What is the role of the enzyme surrounding the active site during the formation of the enzyme-substrate complex?

Answer 5

• The enzyme holds the substrate in place (in the active site) so the reaction can take place more easily.
• It makes the reaction happen quicker
• It means the reaction requires less energy

Question 6

What is an important thing to remember about enzymes?

Answer 6

Each enzyme can only catalyse one reaction.

Question 7

What is the induced fit theory?

Answer 7

• The idea that the enzyme’s active site is slightly flexible and can change shape slightly to fit more closely around the substrate.

Question 8

What is activation energy?

Answer 8

• The energy needed in order to break bonds in order to start the reaction
• In cells, enzymes increase the activation energy without increasing temperature.

Question 9

How do substrates bind to the active site?

Answer 9

• Charged surfaces of the substrate and the active site interact
• The attraction of opposite charges distorts the shape of the substrate and helps to make or break bonds.
• Sometimes the active site contains amino acids which may have acidic side chains, creating an acidic environment, helping the reaction

Question 10

How is an acidic environment created?

Answer 10

By the production of hydrogen ions (H+)

Question 11

Define the metabolism of an organism.

Answer 11

The sum of all enzyme controlled reactions happening within the organism

Question 12

Where do metabolic reactions take place?

Answer 12

• Inside the cells

- Outside the cells

Question 13

What are catabolic reactions?

Answer 13

Reactions that cause the break up of substances

Question 14

What are anabolic reactions?

Answer 14

Reactions that cause the building up of substances in/out of the cells

Question 15

How is the ROR found?

Answer 15

Measuring the quantity of the amount of substrate used or the amount of product formed in a given time.

Question 16

What is the initial rate of reaction?

Answer 16

The rapid phase at the start of the reaction

Question 17

What is the initial rate of reaction used for?

Answer 17

To compare the rates of different reactions.

Question 18

What happens to the rate of reaction when the enzyme becomes full?

Answer 18

• The rate of reaction slows
• This is because the active site is full so there won’t be any reactions taking place any more.
• If the enzymes run out, reactions will not take place
• If the substrate runs out, reactions will not take place

Question 19

Why is food often not digested by a CF sufferer?

Answer 19

• Pancreatic ducts usually blocked by layer of mucus
• Therefore, digestive enzymes cannot leave the pancreas and travel to the small intestine
• When food reaches the small intestine, the food is not digested properly because of the lack of digestive enzymes
• The digestion rate slows down.
• Nutrients cannot be taken into the body. This is known as malabsorption.

Question 20

Why do CF sufferers often develop diabetes?

Answer 20

• Digestive enzymes unable to leave pancreas build up inside pancreas.
• Digestive enzymes break down cells inside pancreas instead
• Causes damage to pancreas
• Insulin cells in pancreas are damaged and insulin levels cannot be regulated
• Therefore, person becomes diabetic