Biological system functions
What are the functions of living systems?
All living systems, at all levels of organization, accomplish multiple functions that enable them to:
1️⃣ hold, use, and exchange information*, and
2️⃣ acquire, use, and transform matter and energy.
(*) Biological systems use different kinds of information. Living systems (a) store, use, and transfer genetic information, encoded in DNA, and (b) receive, produce, process and respond to non-genetic information, such as communication signals, and internal and external stimuli (chemical, electrical, sensory stimuli). While not strictly necessary in principle, in practice we found the distinction between genetic and non-genetic information helpful in organizing our thinking about the functions of biological systems.
Examples of biological functions
Note: this is not intended as a comprehensive list of all functions of living systems! It is more of a "list of convenience": a work in progress that reflects our own thinking and experience with articulating some of the functions we explore in our classrooms.
Genetic information flow, storage and exchange
Examples at different levels of organization
Cells:
store genetic information in molecules of DNA (chromosomes)
produce RNA molecules and proteins with specific functions, based on information encoded in genes
replicate their genomes and pass them onto daughter cells through mitosis, meiosis, or binary fission
check the integrity of their genomes and repair damage to DNA
regulate the timing and intensity of expression of their genes; consequently, cells can:
differentiate and acquire specialized forms and functions within multicellular organisms,
activate or inactivate specific genes in response to stimuli
Organisms:
display physical and behavioral traits dependent on their genotypes.
transmit genetic information to their offspring via asexual or sexual reproduction.
Populations:
hold repositories of genetic variation (gene pools, composed of all the alleles carried by all individuals in the population).
move alleles into and out of other populations by migration (gene flow).
Non-genetic information: sensing & responding to stimuli
Coming soon
Transformations of matter and energy
Coming soon
Examples of emergent processes and phenomena
Evolution
Coming soon
Homeostasis
Organisms:
monitor and regulate multiple internal variables through control mechanisms that often use negative feedback loops;
typically maintain internal conditions within narrow, optimal ranges, regardless of changes in the environment;
can respond to changes in environmental conditions by acclimating.
Phenotype
Coming soon