Question

Essay question:

1. Processes of greening response

Answer 1

1. Once a plant obtains sunlight, changes occur in its morphology and biochemistry. Sunlight acts as a signal. These signals can be whether internal or external, and they are first detected by receptors, which are proteins that can change shape in response to a stimulus. When the light signal is received, it is responsible to produce a response called de-etiolation or greening. This process causes the stem elongation slowly, leaf expansion, and the increased production of chlorophyll. Phytochrome acts as a receptor for the de-etiolation in plants. It can differ from other receptors because it is in the cytoplasm instead of the plasma membrane. In de-etiolation, each activated phytochrome is responsible to give rise to a second messenger, where each can lead to the activation of 100s of molecules of a specific enzyme. Second messengers are responsible to turn on proton pumps, stimulate secretion of wall materials and activate transcription factors.