# Cellular respiration: how you burn food

> A process map exported from forks.world (https://forks.world). Author: Brian. Source: https://forks.world/p/cmv0ie350001ijw06ka2quchu
> 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: Food (glucose), The cell
- Technology / systems: The cytoplasm, The mitochondrion

## 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`.

## Cellular respiration: how you burn food

Lanes:
- Food (glucose): person / role (id `food`)
- The cytoplasm: technology / system (id `cyto`)
- The mitochondrion: technology / system (id `mito`)
- The cell: person / role (id `cell`)

Steps, in the order they run:

1. **Glucose arrives in the cell** [start; Food (glucose); id `r1`]
   - then Glycolysis splits it into two pyruvates
2. **Glycolysis splits it into two pyruvates** [subprocess; The cytoplasm; id `r2`], opens the detail layer "Glycolysis"
   - then Is there oxygen?
3. **Is there oxygen?** [decision; The cell; id `r3`]
   - if "Yes" go to Pyruvate enters the mitochondrion; if "No" go to Fermentation recycles NAD+ so glycolysis can continue
4. **Pyruvate enters the mitochondrion** [task; The mitochondrion; id `r4`]
   - then The Krebs cycle strips off the electrons
5. **The Krebs cycle strips off the electrons** [subprocess; The mitochondrion; id `r5`], opens the detail layer "The Krebs cycle"
   - then The electron transport chain pumps protons
6. **The electron transport chain pumps protons** [task; The mitochondrion; id `r6`]
   - then ATP synthase spins out about 30 ATP
7. **ATP synthase spins out about 30 ATP** [task; The mitochondrion; id `r7`]
   - then ATP powers the cell
8. **ATP powers the cell** [end; The cell; id `r10`]
9. **Fermentation recycles NAD+ so glycolysis can continue** [task; The cytoplasm; id `r8`]
   - then Animal or yeast?
10. **Animal or yeast?** [decision; The cell; id `r9`]
   - if "Animal" go to Lactic acid builds up: your muscles burn; if "Yeast" go to Alcohol and CO2: bread rises, beer bubbles
11. **Lactic acid builds up: your muscles burn** [task; The cell; id `r9a`]
   - then ATP powers the cell
12. **Alcohol and CO2: bread rises, beer bubbles** [task; The cell; id `r9b`]
   - then ATP powers the cell

```mermaid
flowchart LR
  subgraph l_food["Food (glucose)"]
    n_r1(["Glucose arrives in the cell"])
  end
  subgraph l_cyto["The cytoplasm"]
    n_r2[["Glycolysis splits it into two pyruvates"]]
    n_r8["Fermentation recycles NAD+ so glycolysis can continue"]
  end
  subgraph l_mito["The mitochondrion"]
    n_r4["Pyruvate enters the mitochondrion"]
    n_r5[["The Krebs cycle strips off the electrons"]]
    n_r6["The electron transport chain pumps protons"]
    n_r7["ATP synthase spins out about 30 ATP"]
  end
  subgraph l_cell["The cell"]
    n_r3{"Is there oxygen?"}
    n_r9{"Animal or yeast?"}
    n_r9a["Lactic acid builds up: your muscles burn"]
    n_r9b["Alcohol and CO2: bread rises, beer bubbles"]
    n_r10(["ATP powers the cell"])
  end
  n_r1 --> n_r2
  n_r2 --> n_r3
  n_r3 -->|"Yes"| n_r4
  n_r3 -->|"No"| n_r8
  n_r4 --> n_r5
  n_r5 --> n_r6
  n_r6 --> n_r7
  n_r7 --> n_r10
  n_r8 --> n_r9
  n_r9 -->|"Animal"| n_r9a
  n_r9 -->|"Yeast"| n_r9b
  n_r9a --> n_r10
  n_r9b --> n_r10
```

### Glycolysis (detail of step "Glycolysis splits it into two pyruvates")

Lanes:
- The cytoplasm: technology / system (id `cyto`)

Steps, in the order they run:

1. **Spend 2 ATP to energize the glucose** [start; The cytoplasm; id `g1`]
   - then Split the 6-carbon sugar into two 3-carbon pieces
2. **Split the 6-carbon sugar into two 3-carbon pieces** [task; The cytoplasm; id `g2`]
   - then Collect 4 ATP and 2 NADH
3. **Collect 4 ATP and 2 NADH** [task; The cytoplasm; id `g3`]
   - then Net gain: 2 ATP
4. **Net gain: 2 ATP** [end; The cytoplasm; id `g4`]

```mermaid
flowchart LR
  subgraph l_cyto["The cytoplasm"]
    n_g1(["Spend 2 ATP to energize the glucose"])
    n_g2["Split the 6-carbon sugar into two 3-carbon pieces"]
    n_g3["Collect 4 ATP and 2 NADH"]
    n_g4(["Net gain: 2 ATP"])
  end
  n_g1 --> n_g2
  n_g2 --> n_g3
  n_g3 --> n_g4
```

### The Krebs cycle (detail of step "The Krebs cycle strips off the electrons")

Lanes:
- The mitochondrion: technology / system (id `mito`)

Steps, in the order they run:

1. **Acetyl-CoA joins oxaloacetate to make citrate** [start; The mitochondrion; id `k1`]
   - then Strip off CO2 and capture electrons as NADH and FADH2
2. **Strip off CO2 and capture electrons as NADH and FADH2** [task; The mitochondrion; id `k2`]
   - then Back to oxaloacetate?
3. **Back to oxaloacetate?** [decision; The mitochondrion; id `k3`]
   - if "Yes" go to The ring is ready for the next acetyl-CoA; if "No — next step in the ring" go to Strip off CO2 and capture electrons as NADH and FADH2
4. **The ring is ready for the next acetyl-CoA** [end; The mitochondrion; id `k4`]

```mermaid
flowchart LR
  subgraph l_mito["The mitochondrion"]
    n_k1(["Acetyl-CoA joins oxaloacetate to make citrate"])
    n_k2["Strip off CO2 and capture electrons as NADH and FADH2"]
    n_k3{"Back to oxaloacetate?"}
    n_k4(["The ring is ready for the next acetyl-CoA"])
  end
  n_k1 --> n_k2
  n_k2 --> n_k3
  n_k3 -->|"Yes"| n_k4
  n_k3 -->|"No — next step in the ring"| n_k2
```

## Full data (JSON)

```json
{
  "title": "Cellular respiration: how you burn food",
  "maps": {
    "m_root": {
      "id": "m_root",
      "lanes": [
        {
          "id": "food",
          "name": "Food (glucose)",
          "type": "person"
        },
        {
          "id": "cyto",
          "name": "The cytoplasm",
          "type": "system"
        },
        {
          "id": "mito",
          "name": "The mitochondrion",
          "type": "system"
        },
        {
          "id": "cell",
          "name": "The cell",
          "type": "person"
        }
      ],
      "steps": [
        {
          "id": "r1",
          "kind": "start",
          "lane": "food",
          "next": [
            {
              "to": "r2"
            }
          ],
          "uses": [],
          "label": "Glucose arrives in the cell"
        },
        {
          "id": "r2",
          "kind": "subprocess",
          "lane": "cyto",
          "next": [
            {
              "to": "r3"
            }
          ],
          "uses": [],
          "child": "m_glyco",
          "label": "Glycolysis splits it into two pyruvates"
        },
        {
          "id": "r3",
          "kind": "decision",
          "lane": "cell",
          "next": [
            {
              "to": "r4",
              "label": "Yes"
            },
            {
              "to": "r8",
              "label": "No"
            }
          ],
          "uses": [],
          "label": "Is there oxygen?"
        },
        {
          "id": "r4",
          "kind": "task",
          "lane": "mito",
          "next": [
            {
              "to": "r5"
            }
          ],
          "uses": [],
          "label": "Pyruvate enters the mitochondrion"
        },
        {
          "id": "r5",
          "kind": "subprocess",
          "lane": "mito",
          "next": [
            {
              "to": "r6"
            }
          ],
          "uses": [],
          "child": "m_krebs",
          "label": "The Krebs cycle strips off the electrons"
        },
        {
          "id": "r6",
          "kind": "task",
          "lane": "mito",
          "next": [
            {
              "to": "r7"
            }
          ],
          "uses": [],
          "label": "The electron transport chain pumps protons"
        },
        {
          "id": "r7",
          "kind": "task",
          "lane": "mito",
          "next": [
            {
              "to": "r10"
            }
          ],
          "uses": [],
          "label": "ATP synthase spins out about 30 ATP"
        },
        {
          "id": "r8",
          "kind": "task",
          "lane": "cyto",
          "next": [
            {
              "to": "r9"
            }
          ],
          "uses": [],
          "label": "Fermentation recycles NAD+ so glycolysis can continue"
        },
        {
          "id": "r9",
          "kind": "decision",
          "lane": "cell",
          "next": [
            {
              "to": "r9a",
              "label": "Animal"
            },
            {
              "to": "r9b",
              "label": "Yeast"
            }
          ],
          "uses": [],
          "label": "Animal or yeast?"
        },
        {
          "id": "r9a",
          "kind": "task",
          "lane": "cell",
          "next": [
            {
              "to": "r10"
            }
          ],
          "uses": [],
          "label": "Lactic acid builds up: your muscles burn"
        },
        {
          "id": "r9b",
          "kind": "task",
          "lane": "cell",
          "next": [
            {
              "to": "r10"
            }
          ],
          "uses": [],
          "label": "Alcohol and CO2: bread rises, beer bubbles"
        },
        {
          "id": "r10",
          "kind": "end",
          "lane": "cell",
          "next": [],
          "uses": [],
          "label": "ATP powers the cell"
        }
      ],
      "title": "Cellular respiration: how you burn food",
      "parent": null
    },
    "m_glyco": {
      "id": "m_glyco",
      "lanes": [
        {
          "id": "cyto",
          "name": "The cytoplasm",
          "type": "system"
        }
      ],
      "steps": [
        {
          "id": "g1",
          "kind": "start",
          "lane": "cyto",
          "next": [
            {
              "to": "g2"
            }
          ],
          "uses": [],
          "label": "Spend 2 ATP to energize the glucose"
        },
        {
          "id": "g2",
          "kind": "task",
          "lane": "cyto",
          "next": [
            {
              "to": "g3"
            }
          ],
          "uses": [],
          "label": "Split the 6-carbon sugar into two 3-carbon pieces"
        },
        {
          "id": "g3",
          "kind": "task",
          "lane": "cyto",
          "next": [
            {
              "to": "g4"
            }
          ],
          "uses": [],
          "label": "Collect 4 ATP and 2 NADH"
        },
        {
          "id": "g4",
          "kind": "end",
          "lane": "cyto",
          "next": [],
          "uses": [],
          "label": "Net gain: 2 ATP"
        }
      ],
      "title": "Glycolysis",
      "parent": {
        "map": "m_root",
        "step": "r2"
      }
    },
    "m_krebs": {
      "id": "m_krebs",
      "lanes": [
        {
          "id": "mito",
          "name": "The mitochondrion",
          "type": "system"
        }
      ],
      "steps": [
        {
          "id": "k1",
          "kind": "start",
          "lane": "mito",
          "next": [
            {
              "to": "k2"
            }
          ],
          "uses": [],
          "label": "Acetyl-CoA joins oxaloacetate to make citrate"
        },
        {
          "id": "k2",
          "kind": "task",
          "lane": "mito",
          "next": [
            {
              "to": "k3"
            }
          ],
          "uses": [],
          "label": "Strip off CO2 and capture electrons as NADH and FADH2"
        },
        {
          "id": "k3",
          "kind": "decision",
          "lane": "mito",
          "next": [
            {
              "to": "k4",
              "label": "Yes"
            },
            {
              "to": "k2",
              "label": "No — next step in the ring"
            }
          ],
          "uses": [],
          "label": "Back to oxaloacetate?"
        },
        {
          "id": "k4",
          "kind": "end",
          "lane": "mito",
          "next": [],
          "uses": [],
          "label": "The ring is ready for the next acetyl-CoA"
        }
      ],
      "title": "The Krebs cycle",
      "parent": {
        "map": "m_root",
        "step": "r5"
      }
    }
  }
}
```