Month: September 2022

INPUT-OUTPUT BIOLOGY. “The history of life can be described as the evolution of systems that manipulate one set of symbols representing inputs into another set of symbols that represent outputs.” https://www.nature.com/articles/35011540 View in LinkedIn

CIRCUITRY ANALOGY. “Just as electrical engineers design circuits to perform specific functions, modules have evolved to perform biological functions. The properties of a module's components and molecular connections between them are analogous to the circuit diagram of an electrical device. As biologists we often try to deduce the circuitry of modules by listing their component parts and determining how changing the input of the module affects its output.” https://www.nature.com/articles/35011540 View in LinkedIn

HUMPTY DUMPTY. “It is thus unlikely that we can deduce the circuity or a higher-level description of a module solely from genome-wide information about gene expression and physical interactions between proteins. Solving this problem is likely to require additional types of information and finding general principles that govern the structure and function of modules.” https://www.nature.com/articles/35011540 View in LinkedIn

ENGINEERING TRICKS. “A number of the design principles of biological systems are familiar to engineers. Positive feedback loops can drive rapid transitions between two different stable states of a system, and negative feedback loops can maintain an output parameter within a narrow range, despite widely fluctuating input.” https://www.nature.com/articles/35011540 View in LinkedIn

MORE ENGINEERING DEVICES. “Coincidence detection systems require two or more events to occur simultaneously in order to activate an output. Amplifiers are built to minimize noise relative to signal, for instance by choosing appropriate time constants for the circuits. Parallel circuits (fail-safe systems) allow an electronic device to survive failures in one of the circuits.” https://www.nature.com/articles/35011540 View in LinkedIn

ENGINEERING IN BIOLOGY. “Designs such as these are common in biology. For example, one set of positive feedback loops drives cells rapidly into mitosis, and another makes the exit from mitosis a rapid and irreversible event. Negative feedback in bacterial chemotaxis allows the sensory system to detect subtle variations in an input signal whose absolute size can vary by several orders of magnitude.” https://www.nature.com/articles/35011540 View in LinkedIn

MORE BIOLOGY DEVICES. “Coincidence detection lies at the heart of much of the control of gene transcription in eukaryotes, in which the promoters that regulate gene transcription must commonly be occupied by several different protein transcription factors before a messenger RNA can be produced.” https://www.nature.com/articles/35011540 View in LinkedIn

FAIL-SAFE DEVICES. “DNA replication involves a fail-safe system of error correction, with proofreading by the DNA polymerase backed up by a mismatch repair process that removes incorrect bases after the polymerase has moved on. A failure in either process still allows cells to make viable progeny, but simultaneous failure of both is lethal. In both biological and man-made systems, reducing the frequency of failure often requires an enormous increase in the complexity of circuits.” https://www.nature.com/articles/35011540 View in LinkedIn

CONTROL OF NOISE. “Biological systems can both resist and exploit random fluctuations, or noise. Thus, evolutionary adaptation depends on DNA being mutable, but because most mutations are neutral or deleterious, the rate of mutation is under rigorous genetic control.” https://www.nature.com/articles/35011540 View in LinkedIn

THE LIMITS OF KNOWLEDGE. “We already know the laws that govern the behavior of matter under all but the most extreme conditions.” (Stephen Hawking, A Brief History of Time, page 168.) https://en.m.wikipedia.org/wiki/A_Brief_History_of_Time View in LinkedIn