⊙ telomere.digital chapter index
a documentary in five chapters

TELOMERE.DIGITAL

Each cell carries a stopwatch at the end of its chromosomes. This is what it sounds like, slowed down.

runtime 38 min · 5 chapters stock 35mm · documentary subjects human, mouse, hela
01 opening sequence

The end is not the end.
It is, in fact, a hat.

Every chromosome ends in a cap of repetitive DNA. In humans, the sequence TTAGGG is repeated thousands of times, folded into a loop, and held by a small troupe of proteins called shelterin. Without this cap the cell mistakes its own chromosomes for damage.

PL.01 Telomere cap on chromosome 17p, terminal 6 kb. Imaged via FISH; rendered duotone for clarity.
02 the clock

Every division costs
about fifty letters.

DNA polymerase cannot fully copy the very end of a linear chromosome. Each replication leaves a small overhang unfinished, and so the cap shortens by 50–100 base pairs every time the cell divides. The cell counts with its own erosion.

8 – 15 kbp at birth
3 – 6 kbp in late life
~50 bp/div erosion rate
50 ± 10 divisions Hayflick limit

The sequence is not random. TTAGGG can fold into a G-quadruplex, a four-stranded knot stabilized by hydrogen-bonded guanines. The cell uses this knot as a punctuation mark. The end of the sentence.

03 the enzyme

An enzyme that
writes its own template.

TERT — protein subunit TERC — RNA template
PL.02 Telomerase, schematic. The enzyme carries its own RNA blueprint.

Telomerase is a reverse transcriptase that carries its own template. It binds the chromosome end, reads from a piece of internal RNA, and writes TTAGGG back where the polymerase left off. In adults it works only in stem cells, germ cells, and — too well — in cancer cells, where its reactivation is one of the few hallmarks shared across tumor types.

04 the field

Length, but not
in any simple sense.

The fashionable measure of telomere health is length, in base pairs, in white blood cells. The fashion is roughly correct and nearly always misleading. Average length tells you nothing about the shortest telomere — and the cell reacts to its shortest, not its average.

  1. i Mean telomere length correlates weakly with chronological age.
  2. ii Shortest-telomere length predicts senescence onset within an order of magnitude.
  3. iii Length is a noisy biomarker; trajectory is a better one.
  4. iv Stress, sleep, smoking, and resistance training all leave measurable traces.
05 closing

A small piece of
repetitive geometry.

A telomere is not a clock; it's a budget. The cell spends it as it works. Some cells refill it; most do not. What looks like aging at the level of tissue is, at the level of chromosome, a slow accountancy in six-letter words.

The recording stops here. The chromosome continues, slightly shorter than when we started.

⊙ telomere.digital — a science documentary in five chapters stock 35mm · grain ISO 800 · neon 100Hz