Analogies are used as a comparison between two things, typically for the purpose of explanation or clarification.
The claim that cells are factories is both an analogy resembling human-made factories, but cells are as well defacto and literally a megacity of interlinked self-replicating factories.
A factory is a manufacturing plant or production plant, usually consisting of buildings and machinery, or more commonly a complex having several buildings, where workers manufacture goods or operate machines processing one product into another.
Factory is from Latin, and means fabricare, or make. Produce, manufacture. A factory or manufacturing plant is a site, usually consisting of buildings and machinery, or more commonly a complex having several buildings, where, in fully automated factories, for example, pre-programmed robots, manufacture goods or operate machines processing one product into another. And that's PRECISELY what cells do. They produce other cells through self-replication, through complex machine processing, computing, etc. They produce all organelles, proteins, membranes, parts, they make a copy of themselves. Self-replication is a marvel of engineering. the most advanced method of manufacturing. And fully automated. No external help required. If we could make factories like that, we would be able to create a society where machines do all the work for us, and we would have time only to entertain us, no work, nor money needed anymore..... And if factories could evolve to produce subsequently better, more adapted products, that would add even further complexity, and point to even more requirement of pre-programming to get the feat done.
The fact that cells self-replicate substantiates and reinforces the inference of intelligent design gigantically. If man were able to make self-replicating, fully automated robotic factories using in-situ resources, that would be a game-changing technology for all of humanity. This is a monumental challenge. The number of processes involved and parts to build complex machinery is very large. We don't have any factory without human control or intervention.
And even if we eventually get there one day, raw material inputs would still have to be managed by man. Cells have sophisticated gates in the membrane, which sort out what materials can be permitted to get in, and waste products out of the cell. They have even sophisticated machines on the membrane surface, like amazing molecular assembly lines called nonribosomal peptide synthetase, which are protein nanofactories. They detect, attract, and transform iron in the environment into siderophores, which is iron in a form that can be mobilized, uptaken and imported into the cell to manufacture protein co-factors, Iron-sulfur cores used as the catalyzers of enzyme reactions in the core pocket of proteins.
Each factory would also need the means to replicate and copy the information storage device, the hard disk, equivalent to the DNA molecule, and the information content. That is staggeringly complex.The Molecular Fabric of Cells
BIOTOL, B.C. Currell and R C.E Dam-Mieras (Auth.)
The central theme of both of these texts is to consider cells as biological factories. Cells are, indeed, outstanding factories. Each cell type takes in its own set of chemicals and making its own collection of products. The range of products is quite remarkable and encompasses chemically simple compounds such as ethanol and carbon dioxide as well as the extremely complex proteins, carbohydrates, lipids, nucleic acids, and secondary products.
Membranes represent the walls of the cellular factory. Membranes control what comes into the factory and what leaves. We may view the cytoplasm and its surrounding plasma membrane as being the workshop of the chemical factory. The Golgi apparatus, another membranous structure embedded in the cytoplasm, is also involved in the processing of macromolecules made within the cell. Its special properties are for modifying cell products so that they can be exported from the cell. In our chemical factory, they are the packaging and exporting department. Enzymes are indeed rather like the workers in a large complex industrial process. Each is designed
to carry out a specific task in a specific area of the factory.
To understand how a factory operates requires knowledge of the tools and equipment available within the factory and how these tools are organized. We might anticipate that our biological factories will be comprised of structural and functional elements.
Mammalian cell factories
are typically complex production systems as productivity and product quality are controlled by a large number of coordinated metabolic reactions
https://www.sciencedirect.com/topics/engineering/cell-factoryPlant Cells as Chemical Factories: Control and Recovery of Valuable Products
https://link.springer.com/chapter/10.1007/978-94-017-0641-4_14Microbial cell factory is an approach to bioengineering which considers microbial cells as a production facility in which the optimization process largely depends on metabolic engineering
https://en.wikipedia.org/wiki/Microbial_cell_factoryMicrobial Cell Factories is an open access peer-reviewed journal that covers any topic related to the development, use and investigation of microbial cells as producers of recombinant proteins and natural products
https://microbialcellfactories.biomedcentral.com/Fine Tuning our Cellular Factories: Sirtuins in Mitochondrial Biology
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3111451/Cells As Molecular Factories
Eukaryotic cells are molecular factories in two senses: cells produce molecules and cells are made up of molecules.
http://serendip.brynmawr.edu/exchange/bioactivities/cellmolecularMichael Denton: Evolution: A Theory In Crisis:The cell is a veritable micro-miniaturized factory containing thousands of exquisitely designed pieces of intricate molecular machinery, made up altogether of one hundred thousand million atoms, far more complicated than any machine built by man and absolutely without parallel in the non-living world. Ribosome: Lessons of a molecular factory construction
https://link.springer.com/article/10.1134/S0026893314040116Nucleolus: the ribosome factory
https://www.ncbi.nlm.nih.gov/pubmed/18712681Ribosome: The cell city's factories
In the cell, there are production lines, in this case, manufacturing new proteins of many different sorts. New goods and products are continually being manufactured from raw materials. In cities this takes place in workshops and factories. Raw materials are transformed, usually in a sequence of steps on a production line, into finished products. The process is governed by a clear set of instructions or specifications. In some cases the final products are for immediate or local use, in others they are packaged for export.The Cell's Protein Factory in Action
What looks like a jumble of rubber bands and twisty ties is the ribosome, the cellular protein factory.
https://www.livescience.com/41863-ribosomes-protein-factory-nigms.htmlChloroplasts are the microscopic factories
on which all life on Earth is based.
https://www.quora.com/What-is-chloroplast-For-what-it-is-usedVisualization of the active expression site locus by tagging with green fluorescent protein shows that it is specifically located at this unique pol I transcriptional factory.
http://www.nature.com/nature/journal/v414/n6865/full/414759a.htmlThere are millions of protein factories in every cell. Surprise, they’re not all the same
http://www.sciencemag.org/news/2017/06/there-are-millions-protein-factories-every-cell-surprise-they-re-not-all-sameRough ER is also a membrane factory for the cell; it grows in place by adding membrane proteins and phospholipids to its own membrane.
https://en.wikibooks.org/wiki/Cell_Biology/Print_versionEndoplasmic reticulum: Scientists image 'parking garage' helix structure in protein-making factory
Theoretical biologists at Los Alamos National Laboratory have used a New Mexico supercomputer to aid an international research team in untangling another mystery related to ribosomes -- those enigmatic jumbles of molecules that are the protein factories
of living cells.
https://phys.org/news/2010-12-scientists-ratchet-cellular-protein-factory.htmlThe molecular factory that translates the information from RNA to proteins is called the "ribosome"
https://phys.org/news/2014-08-key-worker-protein-synthesis-factory.htmlQuality control in the endoplasmic reticulum protein factoryThe endoplasmic reticulum (ER) is a factory where secretory proteins are manufactured, and where stringent quality-control systems ensure that only correctly folded proteins are sent to their final destinations. The changing needs of the ER factory are monitored by integrated signalling pathways that constantly adjust the levels of folding assistants.
The cell is a mind-bogglingly complex and intricate marvel of nano-technology. Every one of the trillions of cells in your body is not “like” an automated nano-factory. It is an automated nano-factory.