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As a #scientist I think it’s important that we debunk the popular #myths & misconceptions of our fields of research. Having recently joined #Mastodon during the great #TwitterMigration, I’ll try to recreate some of my prior threads on misleading metaphors in #scicomm of #genetics & to adapt them for this platform.
First up: contrary to what you may have heard, your genome is not a blueprint. Read on to find out why...1/6
#DNA is often called a “blueprint for life”. A blueprint is an architect plan, technical drawing or engineering design. And DNA does contain information to guide construction, in this case of a living organism. Beyond that, the analogy rapidly breaks down.
For blueprints, there’s 1-to-1 mapping between an element of a design & its counterpart in the final construction. “DNA as a blueprint” implies that individual #genes show 1-to-1 mappings with parts of a body and/or its functions. Not so...2/6
...Many #genes encode proteins & these are the ones we know most about. Their linear #DNA sequence holds information for stringing together amino-acids (out of 20 alternatives) in a particular order. This order determines how the string folds into a 3-dimensional shape. That shape determines the functions of the encoded protein. Your genome has ~20,000 protein-coding genes, with an astonishing array of roles; enzymes, hormones, receptors, signaling factors, structural proteins etc. ...3/6
...Proteins work together in complex #networks, building & maintaining a living body of a myriad cell types, with different #genes switched on/off. These #molecular networks include genes that build proteins which regulate activity of other genes. Even hub genes don’t show 1-to-1 mapping to outcomes at levels of cells, tissues, or organisms. For example, PAX6, a gene important for eye development, doesn’t direct this process by itself & also plays multiple other roles elsewhere in the body...4/6
...Unlike a blueprint, we've no hope of reverse engineering a #genome by examining appearance of the organism or organisation of its tissues. (Cells carry copies of the genome, so we can directly access the #DNA, but that’s a different issue.)
Why isn’t reverse engineering feasible? Because genomes guide building of bodies through networks of gene activity interacting with other intrinsic & external factors via #developmental cascades, as nicely captured in this image from @WiringtheBrain ...5/6
...To me, the blueprint analogy has little explanatory value & is reminiscent of the homunculus fallacy in accounts of vision (a tiny person in your brain viewing light patterns on your retina). Some describe genes as recipes, but that still fails to reflect core aspects of how #genomes encode biological info.
The reach of #genetics is increasing, with relevance to disease, health, society, & education. We need to communicate its concepts in an accessible way while avoiding broken metaphors. 6/6
@ProfSimonFisher Thank you. My dissertation research in developmental psychobiology screamed the same idea. Certain perturbations to the developmental manifold could yield extremely atypical phenotypes.