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I saw a description of the "minimum requirements" for a cell at http://creation.com/origin-of-life in the section called "What are the minimum requirements for a cell to live?" and I'm wondering if this is scientifically accurate - and if not - what are the real requirements?

[note/warning - the link above is to a creationist site - I'm only quoting this source because I'm trying find the science involved and I didn't find other sources talking about all the necessary pieces. I'm not trying to promote creationism with this question so please don't attack the source or me for bringing it. If you can find a non-creationist source which outlines these requirements, I'll be happy to update the question and remove this source.)

In summary it lists the requirements as follows:

  1. cell membrane
  2. way of storing information (DNA)
  3. way of reading 2. to make components needed
    • RNA polymerase
    • gyrases to untwist DNA
    • ribosomes to make proteins
    • (a few others I omitted b/c I don't know if they're really important)
  4. means of creating fuel (ATP synthase)
  5. a means of copying the information for reproduction

The context of the question is similar to Can scientists create totally synthetic life? and a question I wrote What is the most complex biological organism (or precursors) that we have been able to synthesize from raw materials?.

I'm trying to understand what would be involved in making a cell from scratch. Somehow I found this source but I don't know if it's accurate.

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Yehosef
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  • An even more minimalistic approach would use a single molecule to do the enzymatic job while storing evolvable informations. In this case RNA alone has been proposed as substitute for proteins and DNA in a very minimal cell. In theory also DNA alone could do the same. However the minimal tasks needed to be done: maintain the self (to be compartimentalized), to grow (to have a flux of molecule not in equilibrium), to divide, to maintain the information stably enough to be useful for the next generation and at the same time prone too mutability to evolve. – alec_djinn May 24 '15 at 22:57
  • So to make cells from scratch you would need: amphiphilic molecules to form a membrane, a decent mix of simple molecules (sugars, nucleic acids, peptides) that serve as reactant and building blocks for more complex things, some simple catalyzer (metals, minerals, pepetides, aptamers, etc..) to run the reactions, enough energy to maintain lots of reactions running and keep them far from the equilibrium. Of course, lots of time... – alec_djinn May 24 '15 at 23:03
  • @alec_djinn - could add you comments as an answer so I could upvote them? – Yehosef May 24 '15 at 23:22
  • The website is called creation.com; how ironical :P – WYSIWYG May 25 '15 at 04:40
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    I don't think this question makes much sense. Just because many cells living today satisfy that list of "requirements", that doesn't mean it's the only way to arrive at self-reproducing entities. If you define life as self-reproduction, then any molecule that catalyses its own synthesis is "alive". Beyond self-replication, the requirements gets pretty arbitrary. If you for some reason list a lipid membrane as "required", then yes you need some lipids. Otherwise not. – Roland May 27 '15 at 16:30
  • I specifically didn't mention the minimum requirements of "life" to avoid these discussions. I think the concept of a cell is pretty universal and fundamental aspect of all life today. The fact that some people can choose a definition of less sophisticated structures that have characteristics of life is irrelevant for this question. If you want to make a "cell" (which I think is pretty well defined) - what's involved? – Yehosef May 27 '15 at 21:45
  • looks like from the discussion below that there are some differences in the definition of a "cell" - but it seems there is more consensus than disagreement. – Yehosef May 27 '15 at 21:53
  • "so please don't attack the source" Too late. What you will never find at any creationist website are the "minimal requirements for an intelligence/consciousness", because all such known, scientifically demonstrated minds require... you guessed it, brains, cells, DNA and other parts that ID claims require intelligence, which require cells, etc. ID is a circular fallacy and/or relies totally on faith in minds without parts humans need to be intelligent. Furthermore, ID goes backwards from science; simple to complex, and is thus doomed to fail to answer any life or universe-origins questions. – user6552 Oct 09 '23 at 08:46

2 Answers2

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So, to make cells from scratch you would need: amphiphilic molecules to form a membrane, a decent mix of simple molecules (sugars, nucleic acids, peptides) that serve as reactant and building blocks for more complex things, some simple catalyzer (metals, minerals, pepetides, aptamers, etc..) to run the reactions, enough energy to maintain lots of reactions running and keep them far from the equilibrium. Of course, lots of time...

An even more minimalistic approach would use a single molecule to do the enzymatic job while storing evolvable informations. In this case RNA alone has been proposed as substitute for proteins and DNA in a very minimal cell. In theory also DNA alone could do the same. However the minimal tasks needed to be done: maintain the self (to be compartimentalized), to grow (to have a flux of molecule not in equilibrium), to divide, to maintain the information stably enough to be useful for the next generation and at the same time prone too mutability to evolve.

One more point. Life itself doesn't strictly require to be compartmentalized. You can think of a network of chemical reactions that have the ability to grow, to replicate its components etc but without a cell membrane. However I think that a cell-like form of life is somewhat more likely to happen.

alec_djinn
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  • Why a down vote? The answer is pertinent and correct... – alec_djinn May 26 '15 at 17:34
  • I downvoted because it is basically a list of what is needed in a typical cell, not a minimal cell. Hence it doesn't really address the question. Apologies for not commenting earlier. Happy to upvote after edits. Please ping me. – AliceD May 27 '15 at 14:34
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    Well, maybe it was not clear enough but as catalysts I have listed metals, mineral and peptides instead enzymes and a have specified that a mix of simple molecules will be needed, this is what would make a cell 'minimal'.Indeed the difference between a minimal cell and a proper cell is the complexity of its building blocks. So, the minimal cell requires the same basic components of a normal cell, but you may expect to have a simpler version of them (less complex, less diverse, less optimized). – alec_djinn May 27 '15 at 14:54
  • Thanks :) good edit and +1 for the RNA enzymatic activity – AliceD May 27 '15 at 14:57
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Cell is the structural and functional unit of life, made up of a small mass of protoplasm delimited by a semi permeable membrane and capable of self reproduction without any living medium. This is a proper definition of cell and the minimal requirements would be all these mentioned here. You can also see cell theory by M.J. Schleiden and Theodor Schwann. But most importantly not only genetic information and membrane are required, most required part will be Cell should be capable of self reproduction without any living medium

Like for example RBC is not called cell cause they can't reproduce themselves. But nerve cell is called cell cause though they are not divisible but in embryonic condition the cell division occurred. Also in case of virus, as they can't reproduce without a host,they can't be called cell. Red blood corpuscles aren't cells have a good proof in this article (check blood trivia part) red blood corpuscle

Demietra95
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  • Nucleus in case of eukaryotic. But there should be genetic information in prokaryotic cell. – Demietra95 May 25 '15 at 08:23
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    You do realize that the 'C' in 'RBC' stands for 'cell'? – fileunderwater May 25 '15 at 11:28
  • Good to start with a working definition of a cell though, since it is relatively meaningless to answer this question without one. Are your italicized definition a quote or your own? – fileunderwater May 25 '15 at 11:32
  • @fileunderwater actually no. It stands for corpuscle. Not cell. It's very big misconception and sometimes given in book too which is wrong. – Demietra95 May 25 '15 at 11:33
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    @fileunderwater Originally it was called Red Blood Corpuscles. – WYSIWYG May 25 '15 at 11:34
  • And I Italicised the definition given in any good book of cell biology. Obviously isn't my own. – Demietra95 May 25 '15 at 11:34
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    @WYSIWYG Well, in that case there seems to be some disagreements, since the American Society of Hematology at least seems to label them Red Blood Cells. – fileunderwater May 25 '15 at 11:37
  • If it does then I am afraid there might be some different logic used there. As you will understand, RBC is not cell because it can't self reproduce and greatly depend on bone marrow. Where as cell can definitely reproduce itself. – Demietra95 May 25 '15 at 11:39
  • @Demietra95 Well, that's fine. It's just a good idea to add references when you quote something. "Any good book" could be just about everything, and might not be helpful when answers to the question might actually hinge on the specific definition used. – fileunderwater May 25 '15 at 11:42
  • It's probably because they are derived from erythroblast (~immature RBCs), which do have a nucleus. However, the most useful point is probably that definitions of cells aren't black & white. Lots of cells are dependent on other structures to survive (not just RBCs and bone marrow), and the passage "...capable of self reproduction without any living medium" isn't without problems. – fileunderwater May 25 '15 at 11:51
  • For my study I used a book by Sailesh Guha. If it was capable of self reproduction without a living medium then viruses would have been considered as cells. But they doesn't come under cells. – Demietra95 May 25 '15 at 11:58
  • *they don't come under cells (viruses) . – Demietra95 May 25 '15 at 11:59
  • @fileunderwater Not disagreeing. I just said that originally they were called corpuscles but "red blood cells" is a standard term. – WYSIWYG May 25 '15 at 12:02
  • @Demietra95 Incapable of self-reproduction without a living medium goes for many parasites as well, especially obligate intracellular parasites (e.g. some bacteria, fungi and protozoa), but these are arguably still cells. – fileunderwater May 25 '15 at 12:07
  • @fileunderwater I agree with you that there are various intracellular parasites who are incapable of self reproduction and comes under prokaryotes. But they are part of arguments too. In term of evolution they can be defined as the misg link between molecules – Demietra95 May 25 '15 at 12:12
  • *In term of evolution they are the link between living molecules and and developed cell. But like viruses they are the part of argument whether they are cell or not. Completely It can't be denied neither accepted – Demietra95 May 25 '15 at 12:14
  • I will also recommend you the virology course offered by Columbia University in mooc where it's seen how they are defined as the neither a complete living cell neither non livings. – Demietra95 May 25 '15 at 12:18
  • @Demietra95 I don't fully understand your last comments. Are you saying that many unicellular (especially intracellular parasites) and maybe some multicellular parasites shouldn't be labelled cells? If so, that would be quite controversial and far outside the mainstream. Also, many intracellular parasites are eukaryotes, not prokaryotes. We should probably move this to chat though. – fileunderwater May 25 '15 at 12:36
  • @fileunderwater according to the proposed cell theory it should reproduce. If it doesn't but it has all other living characteristics it doesn't come under a living cell. They stay in a middle portion where neither they can be called living cells neither non living beings. As when they get host, they do reproduce but without it they can't stay alive, they are as good as non living particles. Though I do agree it has many controversies related with it. Even generally in any wiki article or same ranked articles do propose other theories but till now it isn't completely excepted. :) – Demietra95 May 25 '15 at 12:44
  • Here I found a good reference of my words www.redbloodcellbooks.com/rbc7.html check blood trivia part. – Demietra95 May 25 '15 at 20:47
  • Though this may be an old post, there are some things that aren't quite right. First off you are mistaking Terminal Differentiation as not being a cell. Many cells in multicellular organisms are terminally differentiated and will never reproduce themselves. A part of a Red Blood Cells terminal differentiation is to lose most all of its organelles and its genome. Also you make mention of Cell theory, but no where is cell theory does it say that a cell has to be able to replicated itself, only that it arose from a preexisting cell that was living. RBCs fit that definition just fine. – AMR Oct 21 '15 at 04:42