Energy, Electrons, and Networks

Biochemistry, read abstractly, is the study of how living things capture energy, move electrons, and route matter through networks of reactions. This route stays at that level: the patterns that repeat from a kitchen culture to a bacterium to a leaf, in a shape a math page, a garden note, or a software graph can use.

#>five_patterns

Five Patterns That Repeat

An energy currency

Cells do not spend energy directly from food or light. They convert it into a common currency, mostly ATP, and spend that wherever work is needed.

wiki: ATP

Electrons flowing downhill

Redox chemistry moves electrons from a donor to an acceptor. An electron transport chain lets that fall happen in small steps, and the steps pump the gradient that makes ATP.

wiki: electron transport

Catalysts that choose

Enzymes speed particular reactions by many orders of magnitude and ignore others. Which enzymes a cell makes is, in effect, which chemistry it allows.

wiki: enzyme kinetics

Pathways as networks

Metabolism is a graph: molecules are nodes, reactions are edges, and a cell routes flow through it as conditions change. The same network can run in different directions.

wiki: metabolic network

Harvesting light

Photosynthetic organisms catch light with pigments and use it to drive electrons uphill. Not all of them split water or release oxygen; some bacteria photosynthesize using other electron donors entirely.

wiki: photosynthesis

#>what_travels

What Travels

Keep four parts when a pattern leaves the cell: the state you started from, the constraint, the response you actually saw, and a receipt another page can check. That shape is a consequence arc.

A shared currency

ATP lets one reaction pay for another. A token, a common unit, or a compact receipt does the same job. The handoff has to agree on both sides.

Commuting squares

A fall taken in steps

An electron transport chain spends a drop in small steps and keeps a gradient. A slope field, a scheduler, and a reduction in a pan refuse the same move: dumping the whole difference at once.

Slope fields

A catalyst with a range

An enzyme speeds one reaction, then saturates. Below a dose, nothing moves. Past the useful range, more input can stress the system. Vitamins, signaling molecules, mobilized minerals, and cell fragments are different payload classes. Finding one of them does not prove the final change.

Growth language Payload boundaries

A network that can reverse

The same metabolic graph can run another way when the conditions change. What stays the relation is the nodes and edges, not the direction the arrows point this hour.

Graphs Symmetry

Light with a named donor

Some bacteria harvest light without splitting water or releasing oxygen. They use another electron donor. Name the energy source and the donor before calling the process photosynthesis. Pond and soil notes for that case sit with light-fed cultures.

Research categories

#>parallel_theories

Parallel and Competing Theories

Biochemistry was practiced long before it was named, and some of its most consequential results came from China.

Qu, the first koji

Chinese brewers cultivated qu, a starter of molds such as Aspergillus, for millennia to turn grain starch into sugar and alcohol; Japanese koji descends from it. Enzymes, domesticated before anyone could see them.

wiki: Aspergillus oryzae

Tu Youyou and artemisinin

Reading a fourth-century remedy by Ge Hong, Tu Youyou extracted artemisinin at low temperature and gave the world a leading malaria treatment; she shared the 2015 Nobel Prize.

wiki: Tu Youyou