Enzyme Kinetics

Question 1

How do enzymes alter a reaction rate?

Answer 1

Lower the activation energy of a reaction.

Question 2

PLant cell walls are made of a variety of polysaccharides and other compounds, but the primary component is ____.

Answer 2

Cellulose

Question 3

What is the enzyme that we are measuring the activity of in today’s lab?

Answer 3

Cellobiase

Question 4

What is the compound that we will use to detect as a measure of enzyme activity?

Answer 4

p-nitrophenol

Question 5

What is the artificial substrate used to detect enzymatic activity of cellobiase?

Answer 5

p-nitrophenyl glucopyranoside

Question 6

What is the chemical reaction that the artificial substrate undergoes to from the yellow product that is detected as enzymatic activity?

Answer 6

Endocellulase
Exocellulase
Cellobiase

Question 7

What is the function of the stop solution?

Answer 7

It used to stop the solution from continuing the enzymatic activity.

Question 8

What are the two types of cellulases?

Answer 8

endocellulase

exocellulase

Question 9

What were the 2 main objective of this lab?

Answer 9

1- Measure the enzymatic activity of cellobiase; and

2- Identify the optimal conditions for the enzyme

Question 10

The reactant in an enzyme-catalyzed reaction is called the ______.

Answer 10

substrate

Question 11

Once the activation energy is lowered, the chemical reaction occurs at a much ______ rate.

Answer 11

faster

Question 12

What can affect the enzymes’ effectiveness?

Answer 12

Changes in salinity
Changes in pH
Temperature change
Relative concentration of all molecules

Question 13

When an enzyme changes shape, it is said to be ______.

Answer 13

denatured

Question 14

Most enzymes function best at _______.

Answer 14

moderate temperatures (20C-40C)

Question 15

What is V_max?

Answer 15

Maximum rate at which the product can be produced given a particular enzyme and raw materials.

Question 16

_______ catalyze the cellulose to glucose.

Answer 16

Cellulase

Question 17

Humans and other animals produce cellulase. True or False?

Answer 17

False

Question 18

What three tasks must be completed to produce ethanol from plant matter?

Answer 18

1. Pretreatment;
2. Enzymatic hydrolysis;
3. Microbial fermentation

Question 19

Cellulose is broken down into glucose in the following 3 steps by 3 different enzymes. Which are they?

Answer 19

Endocellulases
Exocellulases
Cellobiases

Question 20

Which enzyme break down the internal bonds of the long chains of glucose molecules that form cellulose?

Answer 20

Endocellulase

Question 21

Which enzyme break the covalent linkage between the glucose units of cellulose that are on the end of the cellulose molecules, releasing cellobiase?

Answer 21

Exocellulase

Question 22

Which enzyme breaks down the cellobiose left behind as a result of the work of the first 2 enzymes?

Answer 22

Cellobiase (B-glucosidase)

Question 23

What is the preferred source of sugar for microbial fermentation?

Answer 23

Glucose

Question 24

What instrument measures the amount of light absorbed by the sample?

Answer 24

Spectrophotometer

Question 25

At what wavelength does the spectrophotometer measure the amount of yellowness of an enzyme?

Answer 25

410 nm

Question 26

The darker the color of yellow a sample, the ____ concentrated the sample.

Answer 26

more

Question 27

What is the constant K_m?

Answer 27

Michaelis constant

Question 28

What does Km describe?

Answer 28

The efficiency of the conversion of substrate to product

Question 29

An enzyme can work at its maximum rate when its active sites are ____ saturated with substrate.

Answer 29

completely

Question 30

What is the Michaelis-Menten equation?

Answer 30

V_o=(V_max * [S]) / (K_m + [S])

Question 31

What is the Michaelis-Menten equation used for?

Answer 31

To predict the rate of product formation in enzymatic reactions

Question 32

What is the Lineweaver-Burk plot?

Answer 32

• A double-reciprocal line graph that plots (1/V_o) as a function of (1/[S]).
• It is used to determine important terms in enzyme kinetics such as K_m and V_max

Question 33

The dissociation constant for the enzyme-substrate is _____.

Answer 33

K_m

Question 34

The greater the value K_m, the ___ tightly the substrate is bound to the enzyme.

Answer 34

less

Question 35

The less the value K_m, the ___ tightly the substrate is bound to the enzyme.

Answer 35

more