Internal Membranes and Enzymes

Question 2

What is lactase?

Answer 2

Lactase is a digestive enzyme that breaks lactose into glucose and galactose. Low levels of lactase can result in lactose intolerance.

Question 3

What are enzymes?

Answer 3

Enzymes are molecules that act as catalysts to speed up biological reactions.

Question 4

What are enzymes primarily made of?

Answer 4

Enzymes are almost always proteins but can also be RNA.

Question 5

How can you recognize enzymes?

Answer 5

Enzymes can be recognized by their names, which typically end in ‘ase’ (e.g., catalase, amylase).

Question 6

What are the functions of proteins?

Answer 6

The functions of proteins include speeding up biochemical reactions, playing a role in cellular communication, movement, storage, and providing structural support.

Question 7

How many different proteins does a human have?

Answer 7

A human has tens of thousands of different proteins.

Question 8

What determines the unique shape of a protein?

Answer 8

The unique shape of a protein is determined by its specific sequence of sub-units (monomers) called amino acids.

Question 9

How are enzymes formed?

Answer 9

Enzymes are formed by linking together a sequence of amino acids.

Question 10

What are the characteristics of enzymes?

Answer 10

Enzymes are complex protein molecules that act as catalysts for biochemical reactions and are formed from chains of many amino acids folded into specific three-dimensional structures.

Question 13

What are cofactors?

Answer 13

Cofactors are either inorganic ions or organic molecules.

Question 14

What are coenzymes?

Answer 14

Coenzymes are specifically organic molecules that assist enzymes.

Question 15

What are active sites?

Answer 15

Active sites are grooves on the surface of enzymes that are unique in shape and size, fitting particular substrates.

Question 16

Can enzymes fit multiple substrates?

Answer 16

Some enzymes can fit multiple substrates and can regulate multiple biological functions.

Question 17

What are catabolic reactions?

Answer 17

Catabolic reactions involve breaking substrates apart and release energy.

Question 18

What are anabolic reactions?

Answer 18

Anabolic reactions involve joining molecules together and require an input of energy.

Question 19

Are enzymes changed during reactions?

Answer 19

No, enzymes are not changed during the reaction and can be used repeatedly.

Question 20

What does substrate-specific mean?

Answer 20

Substrate-specific means enzymes regulate a limited number of biochemical reactions.

Question 21

What is a catalyst?

Answer 21

A catalyst increases the rate of biochemical processes without being used up.

Question 22

What is high specificity in enzymes?

Answer 22

An enzyme with high specificity acts as a catalyst for one substrate only.

Question 23

What is low specificity in enzymes?

Answer 23

An enzyme with low specificity may act as a catalyst for a range of similarly shaped substrates.

Question 24

What are examples of catabolic reactions?

Answer 24

Examples of catabolic reactions include digestion and cellular respiration.

Question 25

What are examples of anabolic reactions?

Answer 25

Examples of anabolic reactions include protein synthesis and CO2 production.

Question 26

What causes bonds to weaken in enzymes?

Answer 26

Heat energy causes bonds to weaken, distorting the groove shape of the active site on the enzyme surface, thus preventing the substrate from binding.

Question 27

What happens if the three-dimensional structure of an enzyme is permanently altered?

Answer 27

The enzyme is said to denature.

Question 28

What factors can affect enzyme activity?

Answer 28

Enzyme activity can be affected by temperature, pH, presence of inhibitors, and concentrations of reactants and products.

Question 29

How do lower temperatures affect activation energy?

Answer 29

Lower temperatures increase the amount of activation energy required.

Question 30

What is competitive inhibition?

Answer 30

Competitive inhibition occurs when similarly shaped binding sites compete for the enzyme. ## Footnote An example is the treatment of methanol poisoning with ethanol.

Question 31

What is the lock and key model?

Answer 31

The lock and key model is a model for enzyme-substrate interaction suggesting the enzyme and the substrate have specific complementary shapes.

Question 32

What happens after the substrate binds to the enzyme?

Answer 32

After substrate binding, an amino acid enzyme reaction occurs, the enzyme changes back to its original shape, and releases the product.

Question 33

What is the difference between the lock and key model and the induced fit model?

Answer 33

In the induced fit model, the enzyme distorts and fits more tightly around the substrate to form the enzyme-substrate complex.