Phototropism and Auxin

PhototropismAnd Auxin

Phototropism is a phenomenon in which a plant grows in the direction of its light source. While growing, plants respond to light by bending and growing in its direction.The growth is controlled by a hormone called auxin.

Auxin structure

Plants produce auxin in the stem, buds, and root tips and send the hormone to other plant cells, causing them to grow.During phototropism, auxin molecules are distributed unevenly, for more auxin flows down the side facing away from the light source. As a result, the side facing away from the plant's light source grows faster than the exposed side.

Auxin

Reception: the ligand (auxin) binds to cell surface receptor on plant cell. (1)Signal Transduction: 2nd messengers (molecules that relay signals received at receptors to target molecules in cytosol and/or nucleus) produced. (2)Cellular Response: auxin regulated gene is transcripted to mRNA and translated to growth proteins. (6)

Effect of Auxin on Plant Growth