Ethylene In Postharvest Technology

Question 1

What is ethylene?

Answer 1

A simple unsaturated two-carbon molecule with a carbon-carbon double bond

Ethylene is involved in various biological activities.

Question 2

What is the first step in ethylene biosynthesis?

Answer 2

The reaction of ATP and L-methionine into S-adenosylmethionine (SAM) by methionine S-adenosyltransferase

This step provides the energy required for the biosynthesis process.

Question 3

What does SAM convert to in the ethylene biosynthesis pathway?

Answer 3

1-aminocyclopropane-1-carboxylic acid (ACC)

This conversion represents the first unique step of ethylene biosynthesis.

Question 4

Which enzyme mediates the conversion of SAM to ACC?

Answer 4

ACC synthase (ACS)

ACS is a highly unstable enzyme and is tightly regulated.

Question 5

What factors influence ethylene biosynthesis?

Answer 5

Increased expression of ACC synthase (ACS)

Overexpression or increased stability of ACS can lead to increased ethylene production.

Question 6

What is the final step of ethylene biosynthesis?

Answer 6

The formation of ethylene from ACC catalyzed by ACC oxidase (ACO)

ACO requires oxygen for its activity.

Question 7

What by-products are released during the formation of ethylene from ACC?

Answer 7

Hydrogen cyanide and carbon dioxide

These are by-products of the reaction catalyzed by ACC oxidase (ACO).

Question 8

Fill in the blank: Ethylene biosynthesis begins with the reaction of ATP and L-methionine into ______.

Answer 8

S-adenosylmethionine (SAM)

This reaction is catalyzed by methionine S-adenosyltransferase.

Question 9

True or False: ACC synthase (ACS) is a stable enzyme that is not regulated in ethylene biosynthesis.

Answer 9

False

ACS is highly unstable and its expression is tightly regulated.