The Seven Pillars of Life

A set of practice flashcards covering Daniel E. Koshland Jr.'s essay on the seven essential principles (PICERAS) defining living systems.

Who wrote the essay 'The Seven Pillars of Life' published in Science in March 2002?

Daniel E. Koshland Jr.

What acronym/mnemonic does Daniel E. Koshland Jr. create to represent the seven pillars of life?

PICERAS, standing for Program, Improvisation, Compartmentalization, Energy, Regeneration, Adaptability, and Seclusion.

What is Daniel E. Koshland Jr.'s brief definition of a living organism when forced to provide one?

An organized unit that can carry out metabolic reactions, defend itself against injury, respond to stimuli, and has the capacity to be at least a partner in reproduction.

What is the first pillar of life (Program), and how is it implemented on Earth?

Program is an organized plan describing ingredients and kinetics over time; on Earth, it is implemented by DNA encoding genes.

What is the second pillar of life (Improvisation), and how is it achieved in Earth's living systems?

mprovisation is when living things adjust to new situations. On Earth, they do this because their DNA sometimes changes, and the best changes help them survive.

What is the third pillar of life (Compartmentalization), and why is simple dilution lethal to a cell?

Compartmentalization keeps ingredients within a defined volume; simple dilution reduces the concentrations of substrates and enzymes, destroying reaction kinetics and killing the cell.

What is the fourth pillar of life (Energy), and what is the major energy source for Earth's biosphere?

Energy compensates for thermodynamic entropy losses in open metabolizing systems; the primary source is the Sun, supplemented by the Earth's internal heat.

What is the fifth pillar of life (Regeneration), and what are two ways living systems accomplish it?

Regeneration compensates for wear and tear and thermodynamic losses; it is accomplished by continuous resynthesis of body constituents and 'starting over' through reproduction/cell division.

According to the transcript, how many times does a normal human heart beat over a lifetime?

$91,980,000$ times (calculated as 60 times a minute, 3600 an hour, and 1,314,000 a year).

How does the 'starting over' process of Regeneration differ between Escherichia coli and Homo sapiens?

For Escherichia coli, starting over occurs via cell division, whereas for Homo sapiens, it occurs through the birth of an infant.

What is the fundamental difference between Improvisation (Pillar 2) and Adaptability (Pillar 6)?

Improvisation alters the core program over evolutionary time via mutation and selection, whereas Adaptability is a fast behavioral or physiological feedback response built into the existing program.

What is the seventh pillar of life (Seclusion), and how is it maintained?

Seclusion prevents cross-reactions between metabolic pathways; it is maintained by the high specificity of enzymes and nucleic acid interactions.

Over how many orders of magnitude can the human eye adapt to light levels according to the essay?

10 orders of magnitude ($10^{10}$).

What analogy is used in the transcript to describe the function of Seclusion in metabolic pathways?

Insulating an electrically conducting wire so it is not short-circuited by contact with another wire.