# Mitosis: how one cell becomes two

> A process map exported from forks.world (https://forks.world). Author: Brian. Source: https://forks.world/p/cmv0ie0oz000yjw06kih9a6ph
> It describes who does what, in what order, and with which technology. Read the plain-language sections first; the JSON at the end is the exact, complete data.

## Summary

- 20 steps across 3 layers
- Persona: The cell, Checkpoint proteins
- Technology / systems: Chromosomes, Spindle fibers

## How to read this file

- A process is made of **layers**. The main layer is the top level; any step of kind `subprocess` opens a detail layer with its own lanes and steps.
- **Lanes** are either persona (people/roles) or technology (systems). Each step belongs to one lane; `using` lists tools a person uses for that step.
- Step kinds: `start`, `task`, `decision` (its arrows carry the answer as a label), `subprocess`, `end`.

## Mitosis: how one cell becomes two

Lanes:
- The cell: person / role (id `cell`)
- Chromosomes: technology / system (id `chrom`)
- Spindle fibers: technology / system (id `spin`)
- Checkpoint proteins: person / role (id `check`)

Steps, in the order they run:

1. **Cell grows and copies its DNA (interphase)** [subprocess; The cell; id `m1`], opens the detail layer "Interphase: the long prep"
   - then Checkpoint: is the DNA fully copied and undamaged?
2. **Checkpoint: is the DNA fully copied and undamaged?** [decision; Checkpoint proteins; id `m2`]
   - if "Yes" go to Prophase: chromosomes condense into visible X shapes; if "No" go to Repair it, or if hopeless, trigger self-destruct (apoptosis)
3. **Prophase: chromosomes condense into visible X shapes** [task; Chromosomes; id `m3`]
   - then Spindle fibers build out from both poles
4. **Spindle fibers build out from both poles** [task; Spindle fibers; id `m4`]
   - then Metaphase: chromosomes line up along the middle
5. **Metaphase: chromosomes line up along the middle** [task; Chromosomes; id `m5`]
   - then Is every chromosome attached to the spindle?
6. **Is every chromosome attached to the spindle?** [decision; Checkpoint proteins; id `m6`]
   - if "Yes" go to Anaphase: sister chromatids are pulled apart; if "No" go to Fibers keep searching for the loose chromosome
7. **Anaphase: sister chromatids are pulled apart** [subprocess; Spindle fibers; id `m7`], opens the detail layer "Anaphase"
   - then Telophase: two new nuclei form
8. **Telophase: two new nuclei form** [task; Chromosomes; id `m8`]
   - then Cytokinesis: the cell pinches in two
9. **Cytokinesis: the cell pinches in two** [task; The cell; id `m9`]
   - then Two genetically identical daughter cells
10. **Two genetically identical daughter cells** [end; The cell; id `m10`]
11. **Fibers keep searching for the loose chromosome** [task; Spindle fibers; id `m6a`]
   - then Is every chromosome attached to the spindle?
12. **Repair it, or if hopeless, trigger self-destruct (apoptosis)** [task; Checkpoint proteins; id `m2a`]
   - then Checkpoint: is the DNA fully copied and undamaged?

```mermaid
flowchart LR
  subgraph l_cell["The cell"]
    n_m1[["Cell grows and copies its DNA (interphase)"]]
    n_m9["Cytokinesis: the cell pinches in two"]
    n_m10(["Two genetically identical daughter cells"])
  end
  subgraph l_chrom["Chromosomes"]
    n_m3["Prophase: chromosomes condense into visible X shapes"]
    n_m5["Metaphase: chromosomes line up along the middle"]
    n_m8["Telophase: two new nuclei form"]
  end
  subgraph l_spin["Spindle fibers"]
    n_m4["Spindle fibers build out from both poles"]
    n_m6a["Fibers keep searching for the loose chromosome"]
    n_m7[["Anaphase: sister chromatids are pulled apart"]]
  end
  subgraph l_check["Checkpoint proteins"]
    n_m2{"Checkpoint: is the DNA fully copied and undamaged?"}
    n_m2a["Repair it, or if hopeless, trigger self-destruct (apoptosis)"]
    n_m6{"Is every chromosome attached to the spindle?"}
  end
  n_m1 --> n_m2
  n_m2 -->|"Yes"| n_m3
  n_m2 -->|"No"| n_m2a
  n_m2a --> n_m2
  n_m3 --> n_m4
  n_m4 --> n_m5
  n_m5 --> n_m6
  n_m6 -->|"Yes"| n_m7
  n_m6 -->|"No"| n_m6a
  n_m6a --> n_m6
  n_m7 --> n_m8
  n_m8 --> n_m9
  n_m9 --> n_m10
```

### Anaphase (detail of step "Anaphase: sister chromatids are pulled apart")

Lanes:
- Spindle fibers: technology / system (id `spin`)
- Chromosomes: technology / system (id `chrom`)

Steps, in the order they run:

1. **Separase cuts the molecular glue between sister chromatids** [start; Spindle fibers; id `a1`]
   - then Motor proteins walk the chromatids along the fibers
2. **Motor proteins walk the chromatids along the fibers** [task; Spindle fibers; id `a2`]
   - then The poles move further apart
3. **The poles move further apart** [end; Spindle fibers; id `a3`]

```mermaid
flowchart LR
  subgraph l_spin["Spindle fibers"]
    n_a1(["Separase cuts the molecular glue between sister chromatids"])
    n_a2["Motor proteins walk the chromatids along the fibers"]
    n_a3(["The poles move further apart"])
  end
  n_a1 --> n_a2
  n_a2 --> n_a3
```

### Interphase: the long prep (detail of step "Cell grows and copies its DNA (interphase)")

Lanes:
- The cell: person / role (id `cell`)
- Chromosomes: technology / system (id `chrom`)
- Checkpoint proteins: person / role (id `check`)

Steps, in the order they run:

1. **G1: grow and do normal work** [start; The cell; id `i1`]
   - then Big enough and healthy?
2. **Big enough and healthy?** [decision; Checkpoint proteins; id `i2`]
   - if "Yes" go to S phase: copy every chromosome; if "No" go to Rest, or keep growing
3. **S phase: copy every chromosome** [task; Chromosomes; id `i3`]
   - then G2: build extra organelles and proteins
4. **G2: build extra organelles and proteins** [end; The cell; id `i4`]
5. **Rest, or keep growing** [task; The cell; id `i2a`]
   - then Big enough and healthy?

```mermaid
flowchart LR
  subgraph l_cell["The cell"]
    n_i1(["G1: grow and do normal work"])
    n_i2a["Rest, or keep growing"]
    n_i4(["G2: build extra organelles and proteins"])
  end
  subgraph l_chrom["Chromosomes"]
    n_i3["S phase: copy every chromosome"]
  end
  subgraph l_check["Checkpoint proteins"]
    n_i2{"Big enough and healthy?"}
  end
  n_i1 --> n_i2
  n_i2 -->|"Yes"| n_i3
  n_i2 -->|"No"| n_i2a
  n_i2a --> n_i2
  n_i3 --> n_i4
```

## Full data (JSON)

```json
{
  "title": "Mitosis: how one cell becomes two",
  "maps": {
    "m_ana": {
      "id": "m_ana",
      "lanes": [
        {
          "id": "spin",
          "name": "Spindle fibers",
          "type": "system"
        },
        {
          "id": "chrom",
          "name": "Chromosomes",
          "type": "system"
        }
      ],
      "steps": [
        {
          "id": "a1",
          "kind": "start",
          "lane": "spin",
          "next": [
            {
              "to": "a2"
            }
          ],
          "uses": [],
          "label": "Separase cuts the molecular glue between sister chromatids"
        },
        {
          "id": "a2",
          "kind": "task",
          "lane": "spin",
          "next": [
            {
              "to": "a3"
            }
          ],
          "uses": [],
          "label": "Motor proteins walk the chromatids along the fibers"
        },
        {
          "id": "a3",
          "kind": "end",
          "lane": "spin",
          "next": [],
          "uses": [],
          "label": "The poles move further apart"
        }
      ],
      "title": "Anaphase",
      "parent": {
        "map": "m_root",
        "step": "m7"
      }
    },
    "m_root": {
      "id": "m_root",
      "lanes": [
        {
          "id": "cell",
          "name": "The cell",
          "type": "person"
        },
        {
          "id": "chrom",
          "name": "Chromosomes",
          "type": "system"
        },
        {
          "id": "spin",
          "name": "Spindle fibers",
          "type": "system"
        },
        {
          "id": "check",
          "name": "Checkpoint proteins",
          "type": "person"
        }
      ],
      "steps": [
        {
          "id": "m1",
          "kind": "subprocess",
          "lane": "cell",
          "next": [
            {
              "to": "m2"
            }
          ],
          "uses": [],
          "child": "m_inter",
          "label": "Cell grows and copies its DNA (interphase)"
        },
        {
          "id": "m2",
          "kind": "decision",
          "lane": "check",
          "next": [
            {
              "to": "m3",
              "label": "Yes"
            },
            {
              "to": "m2a",
              "label": "No"
            }
          ],
          "uses": [],
          "label": "Checkpoint: is the DNA fully copied and undamaged?"
        },
        {
          "id": "m2a",
          "kind": "task",
          "lane": "check",
          "next": [
            {
              "to": "m2"
            }
          ],
          "uses": [],
          "label": "Repair it, or if hopeless, trigger self-destruct (apoptosis)"
        },
        {
          "id": "m3",
          "kind": "task",
          "lane": "chrom",
          "next": [
            {
              "to": "m4"
            }
          ],
          "uses": [],
          "label": "Prophase: chromosomes condense into visible X shapes"
        },
        {
          "id": "m4",
          "kind": "task",
          "lane": "spin",
          "next": [
            {
              "to": "m5"
            }
          ],
          "uses": [],
          "label": "Spindle fibers build out from both poles"
        },
        {
          "id": "m5",
          "kind": "task",
          "lane": "chrom",
          "next": [
            {
              "to": "m6"
            }
          ],
          "uses": [],
          "label": "Metaphase: chromosomes line up along the middle"
        },
        {
          "id": "m6",
          "kind": "decision",
          "lane": "check",
          "next": [
            {
              "to": "m7",
              "label": "Yes"
            },
            {
              "to": "m6a",
              "label": "No"
            }
          ],
          "uses": [],
          "label": "Is every chromosome attached to the spindle?"
        },
        {
          "id": "m6a",
          "kind": "task",
          "lane": "spin",
          "next": [
            {
              "to": "m6"
            }
          ],
          "uses": [],
          "label": "Fibers keep searching for the loose chromosome"
        },
        {
          "id": "m7",
          "kind": "subprocess",
          "lane": "spin",
          "next": [
            {
              "to": "m8"
            }
          ],
          "uses": [],
          "child": "m_ana",
          "label": "Anaphase: sister chromatids are pulled apart"
        },
        {
          "id": "m8",
          "kind": "task",
          "lane": "chrom",
          "next": [
            {
              "to": "m9"
            }
          ],
          "uses": [],
          "label": "Telophase: two new nuclei form"
        },
        {
          "id": "m9",
          "kind": "task",
          "lane": "cell",
          "next": [
            {
              "to": "m10"
            }
          ],
          "uses": [],
          "label": "Cytokinesis: the cell pinches in two"
        },
        {
          "id": "m10",
          "kind": "end",
          "lane": "cell",
          "next": [],
          "uses": [],
          "label": "Two genetically identical daughter cells"
        }
      ],
      "title": "Mitosis: how one cell becomes two",
      "parent": null
    },
    "m_inter": {
      "id": "m_inter",
      "lanes": [
        {
          "id": "cell",
          "name": "The cell",
          "type": "person"
        },
        {
          "id": "chrom",
          "name": "Chromosomes",
          "type": "system"
        },
        {
          "id": "check",
          "name": "Checkpoint proteins",
          "type": "person"
        }
      ],
      "steps": [
        {
          "id": "i1",
          "kind": "start",
          "lane": "cell",
          "next": [
            {
              "to": "i2"
            }
          ],
          "uses": [],
          "label": "G1: grow and do normal work"
        },
        {
          "id": "i2",
          "kind": "decision",
          "lane": "check",
          "next": [
            {
              "to": "i3",
              "label": "Yes"
            },
            {
              "to": "i2a",
              "label": "No"
            }
          ],
          "uses": [],
          "label": "Big enough and healthy?"
        },
        {
          "id": "i2a",
          "kind": "task",
          "lane": "cell",
          "next": [
            {
              "to": "i2"
            }
          ],
          "uses": [],
          "label": "Rest, or keep growing"
        },
        {
          "id": "i3",
          "kind": "task",
          "lane": "chrom",
          "next": [
            {
              "to": "i4"
            }
          ],
          "uses": [],
          "label": "S phase: copy every chromosome"
        },
        {
          "id": "i4",
          "kind": "end",
          "lane": "cell",
          "next": [],
          "uses": [],
          "label": "G2: build extra organelles and proteins"
        }
      ],
      "title": "Interphase: the long prep",
      "parent": {
        "map": "m_root",
        "step": "m1"
      }
    }
  }
}
```