what is photogene? please can any one give me the exact answer.?

Answer 1

1) Chloroplasts contain electron receptors that reduce the electrons energy to a form usable by the plant. They contain genes encoding their own proteins. These are designated as chloroplast DNA (cpDNA). One gene that is light dependent encodes a polypeptide, a protein, with a mass of 32 kiloDaltons (kD), now called a 'photogene'. It has no known function but its appearance in seedlings, originally grown in the dark, once they are exposed to light, has led to its name; Photogene 32. Hence Photogene 32 is photoregulated.
2) Positively photoregulated regions of chloroplast DNA show increased transcript levels (more DNA is copied into RNA then translated into protein) upon illumination of dark-grown seedlings. Genes within these regions are referred to as photogenes in general

3) A visual image that lasts after the stimulus causing it has stopped. An afterimage, usually negative or in opposite colors, also called photogene.

If you play with a sparkler on the 4th of July you will continue to see it after it has burned out. Your eye continues to signal but reduces the signal from the receptors that received the strongest signal. Once the light ceases the area of reduced signal sends a perception of the image inverted in both brightness and color.

There is also the phosphene - A sensation of light caused when the retina is excitation by mechanical means rather than by light, as when the eyeballs are rubbed through closed lids.