Let there be light

It is dark. A world of soil.

Something is moving.

A tiny seed!

Perhaps round and wrinkly¹.

Root protrudes down, out of thirst,

eager to explore.

The young stem² grows upward, longer and longer,

with a vigour resembling a rattlesnake rising to its defence.

At the top, a hook³ emerges,

a protection against the big harsh terrestrial nature.

Inside the hook are two (or one) young leaflets⁴,

small, pale⁵ and tender,

like folded palms holding what is to come⁶.

Searching!

Searching for light!

A gap breaks in the earth.

Let there be light⁷!

Molecules innumerable⁸ suddenly see-

they shift their shapes,

they touch other molecules,

the other molecules touch others.

A melody, or a song,

hidden in the cacophony of many random encounters⁹.

Some genetic codes are turned on¹⁰,

some proteins are made¹¹,

some reactions begin.

Suddenly, the plant glows green¹².

Tiny solar panels build up inside the cells-

full of tubing and storage tanks¹³.

The lanky stature replaced by a sturdy silhouette¹⁴.

The hook unwinds, and leaflets expand-

as birdwings stretching and flapping in the sun.

Here we are, a tiny seedling!

Ready for a full life ahead.

Footnotes:

1. Specific features of a plant are called “traits”, and traits have genetic basis that follows inheritance laws (see Gregor Mendel’s experiments).

2. Hypocotyl

3. Apical hook

4. Cotyledons

5. Cotyledons accumulate Pchlide (chlorophyll precursor with a yellowish colour) in the dark.

6. Shoot apical meristem

7. How plants change their development in response to light is termed “photomorphogenesis”. A movie by Roger P. Hangarter is  an excellent illustration of this.

8. Photoreceptor proteins

9. A cell is a crowded environment in terms of how many molecules it has. Proteins often bump into each other by chance (see figure below by David S. Goodsell). But many proteins have interactions with specific partners, producing certain biological effects.

10. A process termed transcription

11. A process termed translation

12. In angiosperms the conversion from Pchlide to chlorophyll (with a green colour) is strictly dependent on light. One of the proteins controlling greening in the upstream is Golden2-like (GLK) transcription factor.

13. Chloroplasts are cellular organelles that need light to fully develop. They contain structures such as thylakoid (a structured membrane system) and starch granule (as storage).

14. A type of protein controlling hypocotyl elongation is expansin.