Cell Communication: Phototropism

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by aznboi123
Last updated 6 years ago

Cell Biology

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Cell Communication: Phototropism

Cell Communication in Plants:Phototropism

Phototropism is the growth of plants either toward or away from a light source.

There are 3 main photoreceptors that are involved in phototropism. This includes phototropins, phytochromes, and cryptochromes. Phototropins and cryptochromes sense blue light, while phytochromes sense red and far-red light.

Auxin is a plant hormone that causes plant elongation and growth with high concentrations. Differing concentrations of auxins and different parts of the plant allow for the plant to grow toward the light. It moves between cells through polar auxin transport, a type of active transport, to guide the plant's growth. Most common is indole-3-acetic acid (IAA).

What is phototropism?

What is the signal mechanism?

What type of receptor is involved?

What happens in the signal transduction pathway?

Light hits the photoreceptors on the side of the plant, inducing active transport for auxins to relocate away from the light source. Cells with extra auxin elongate as they grow, causing the plant to bend seemingly toward the light.

As given: auxins are transported due to working photoreceptors and gather in the direction of the light.

Correct Mechanism

Glog by: Derek Lin, Elaine Ho, and Stephanie LinPeriod 1

Graphic of Pathway

If the genes for the carrier proteins for transporting auxin become mutated, their ability to maintain a gradient of auxin may become impaired. For example, phytochrome A deficient tomato plants do not exhibit phototropism to low fluence blue light.

Faulty or Impaired Mechanism

Research is currently geared towards understanding how phototropin stimulation will cause a change in auxin distribution in the plant. As of now, there is little knowledge of about through what mechanism is the signal transduced into auxin movement.

What is still left unknown about phototropism?


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