McClintock's Jumping Genes: Maize Kernel Variegation

Ac/Ds Transposon System

Excision rate per division 8%

Cell divisions simulated 7 (128 cells)

Growth speed 1.0×

Kernel Readout

Pigmented (purple)

Revertant sectors

Avg. sector size

0 cells

Developmental gen.

0 / 0

How it works

In Barbara McClintock's maize, the Ds (Dissociation) element sits inside the C1 pigment gene, knocking it out and leaving the kernel colorless. Ds cannot move on its own — it needs the enzyme made by a second element, Ac (Activator), elsewhere in the genome. When Ac is present, Ds can excise from C1 at any mitotic division, restoring the gene in that cell and every descendant of it, painting a purple sector.

Cell divides -> Ds excises with prob. p (only if Ac present)
Once excised -> gene restored -> ALL daughter cells inherit purple
P(cell still colorless after G divisions) = (1 - p)^G
Earlier excision -> more divisions left -> LARGER sector
Later excision  -> fewer divisions left -> SMALLER sector, more spots

This simulator grows a kernel as a binary lineage tree: starting from one founder cell, each division splits the tissue in the UV map below (alternating axis, like real anticlinal/periclinal cell walls), and at every division each still-colorless lineage independently rolls the excision probability. The result — big blocks of color from early jumps, fine speckling from late ones — is exactly the variegated kernel pattern that led McClintock to propose mobile genetic elements in 1950, work that won her the 1983 Nobel Prize.

+Ac / −Ac — toggles whether the transposase needed to mobilize Ds exists at all; with Ac silent, excision rate is forced to zero (the classic no-Ac control: a fully colorless kernel).
Excision rate — per-division probability p that Ds jumps out in a given colorless lineage.
Cell divisions — depth of the lineage tree (2^G final cells tiled onto the kernel surface).
Grow New Kernel — re-runs the stochastic lineage tree with a fresh random seed and replays the growth animation.

Colorless (Ds intact, C1 off) Purple (Ds excised, C1 on)

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