# Size of individual cells? **URL:** \ **Category:** Factual Questions\ **Created:** [February 5, 2013, 7:04pm UTC](https://boards.straightdope.com/t/size-of-individual-cells/649411 "2013-02-05T19:04:07Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![TruCelt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/trucelt/32/523_2.png) [@TruCelt](https://boards.straightdope.com/u/TruCelt)\ **Post date:** [February 5, 2013, 7:04pm UTC](https://boards.straightdope.com/t/size-of-individual-cells/649411/1 "2013-02-05T19:04:07Z")
This thread [Why were dinosaurs so big? - Cecil's Columns/Staff Reports - Straight Dope Message Board](http://boards.straightdope.com/sdmb/showthread.php?t=680045) reminded me of an old question: Are the individual cells which make up various creatures approximately the same size? I’m thinking specifically of cells which make up multi-cellular animals, I’m aware that single-celled creatures vary greatly in size. And I realized that specialization of a cell will incease or decrease size of that type. But as huge as the dinosaurs were, would their individual cells have been larger? Would an elephant’s muscle or retinal cells any larger than those of a mouse? ---
**Author:** ![Great\_Antibob](https://avatars.discourse-cdn.com/v4/letter/g/e47c2d/32.png) [@Great\_Antibob](https://boards.straightdope.com/u/Great_Antibob)\ **Post date:** [February 5, 2013, 7:21pm UTC](https://boards.straightdope.com/t/size-of-individual-cells/649411/2 "2013-02-05T19:21:46Z")
> [@TruCelt](#): > > But as huge as the dinosaurs were, would their individual cells have been larger? Would an elephant’s muscle or retinal cells any larger than those of a mouse? Cell size doesn’t necessarily scale with animal size. You’ll see a larger variation from cell specialization. For a truly remarkable example, look at a [giant squid axon](http://en.wikipedia.org/wiki/Squid_giant_axon). Those can get up to a millimeter in diameter and are visible to the naked eye. By contrast, human axons are only a few microns. ---
**Author:** ![eltro102](https://avatars.discourse-cdn.com/v4/letter/e/7cd45c/32.png) [@eltro102](https://boards.straightdope.com/u/eltro102)\ **Post date:** [February 5, 2013, 7:25pm UTC](https://boards.straightdope.com/t/size-of-individual-cells/649411/3 "2013-02-05T19:25:24Z")
generally, a cell’s nucleus size is determined (very roughly!!) by the size of the DNA of the animal. Dinosaurs had huge long DNA, so their nucleus sizes were considerably larger. Large cells need large nuclei, for effective mRNA transport (because they have a larger surface area and more pores) and for faster protein assembly in the cytoplasm. Also, by straight-up observation you can clearly see the bone-cells in a dinosaur’s fossils are a lot larger than in other animals. This is thought to be one of the ‘reasons’ junk DNA exists, to pad-out cells and ensure correct nucleus size. From this you can extrapolate that larger animals with longer DNA (which is normally true) will have larger cell sizes, but there are huge variances and you can’t make a perfectly reliable conclusion based on this ---
**Author:** ![bouv](https://avatars.discourse-cdn.com/v4/letter/b/bc8723/32.png) [@bouv](https://boards.straightdope.com/u/bouv)\ **Post date:** [February 5, 2013, 7:25pm UTC](https://boards.straightdope.com/t/size-of-individual-cells/649411/4 "2013-02-05T19:25:54Z")
It’s a complicated question, and the answer is “yes and no.” Some cells in certain animals (notably neurons,) are going to be MUCH bigger. Giraffes and giant squid have neurons that are a few meters long. Even humans have neurons over a meter long. Compare this to a small rodent or bird, who’s largest neuron might be less than a centimeter. ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [February 5, 2013, 8:10pm UTC](https://boards.straightdope.com/t/size-of-individual-cells/649411/5 "2013-02-05T20:10:51Z")
> [@eltro102](#): > > Dinosaurs had huge long DNA, so their nucleus sizes were considerably larger. Can I have a citation for this? To the best of my knowledge, no one has yet isolated any dinosaur DNA at all. There have been a few claims, which haven’t panned out, yet even those that made those claims were only claiming to have isolated a few hundred nucleotides at best. To the OP: there’s a fair bit of variability in cell size. Probably the most dramatic is that between prokaryotic (bacterial) cells and eukaryotic (everything else) cells. [This](http://learn.genetics.utah.edu/content/begin/cells/scale/) site is useful for visualizing relative sizes. ---
**Author:** ![njtt](https://avatars.discourse-cdn.com/v4/letter/n/ecd19e/32.png) [@njtt](https://boards.straightdope.com/u/njtt)\ **Post date:** [February 5, 2013, 8:39pm UTC](https://boards.straightdope.com/t/size-of-individual-cells/649411/6 "2013-02-05T20:39:47Z")
> [@Great\_Antibob](#): > > For a truly remarkable example, look at a [giant squid axon](http://en.wikipedia.org/wiki/Squid_giant_axon). That is actually **squid giant axon** , i.e., the giant axon that is found in a regular squid, not a regular axon from a giant squid; which actually makes its size all the more impressive. (I don’t know if giant squid have giant squid giant axons, but if they do they are probably not much thicker than regular giant squid axons, just longer.) Of course, when it comes to _colossal squid_, all bets are off! ---
**Author:** ![eltro102](https://avatars.discourse-cdn.com/v4/letter/e/7cd45c/32.png) [@eltro102](https://boards.straightdope.com/u/eltro102)\ **Post date:** [February 5, 2013, 11:51pm UTC](https://boards.straightdope.com/t/size-of-individual-cells/649411/7 "2013-02-05T23:51:33Z")
> [@Smeghead](#): > > Can I have a citation for this? To the best of my knowledge, no one has yet isolated any dinosaur DNA at all. There have been a few claims, which haven’t panned out, yet even those that made those claims were only claiming to have isolated a few hundred nucleotides at best. > > To the OP: there’s a fair bit of variability in cell size. Probably the most dramatic is that between prokaryotic (bacterial) cells and eukaryotic (everything else) cells. [This](http://learn.genetics.utah.edu/content/begin/cells/scale/) site is useful for visualizing relative sizes. They haven’t actually found the DNA, but they have looked at the cell sizes, from which they know the properties of the nucleus, from which they can get that they had large DNA to fit into the nucleus, there a number of articles on this on the internet but they all reference [this](http://www.nature.com/nature/journal/v446/n7132/abs/nature05621.html)paper ---
**Author:** ![Bob\_X](https://avatars.discourse-cdn.com/v4/letter/b/4491bb/32.png) [@Bob\_X](https://boards.straightdope.com/u/Bob_X)\ **Post date:** [February 5, 2013, 11:58pm UTC](https://boards.straightdope.com/t/size-of-individual-cells/649411/8 "2013-02-05T23:58:23Z")
Xenophyophorea is a deep-sea phylum of amoeboids (a branch of eukaryotes containing not just little protozoa but also slime molds etc. and the shelled foraminifera, to which the xenophyophores are probably closest) in which each organism is single-celled, and yet can be a few feet in diameter. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [February 6, 2013, 2:29am UTC](https://boards.straightdope.com/t/size-of-individual-cells/649411/9 "2013-02-06T02:29:38Z")
I’ve seen pictures of an amoeba engulfing an arthropod of some sort. Clearly, that arthropod has teeny tiny cells. ---
**Author:** ![artemis](https://avatars.discourse-cdn.com/v4/letter/a/91b2a8/32.png) [@artemis](https://boards.straightdope.com/u/artemis)\ **Post date:** [February 6, 2013, 3:29am UTC](https://boards.straightdope.com/t/size-of-individual-cells/649411/10 "2013-02-06T03:29:52Z")
An unfertilized chicken egg is a single cell, and it’s clearly a much bigger cell than even the largest cell in a human body. Cells can vary enormously in size. ---
**Author:** ![Der\_Trihs](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/der_trihs/32/233_2.png) [@Der\_Trihs](https://boards.straightdope.com/u/Der_Trihs)\ **Post date:** [February 6, 2013, 3:31am UTC](https://boards.straightdope.com/t/size-of-individual-cells/649411/11 "2013-02-06T03:31:43Z")
I’ve read in the past that bird cells are smaller than the cells of other animals; the hypothesis as to why is that it’s an adaption for flight. Smaller cells allow for more relative surface area for each cell, and a higher metabolic rate. ---
**Author:** ![Bob\_X](https://avatars.discourse-cdn.com/v4/letter/b/4491bb/32.png) [@Bob\_X](https://boards.straightdope.com/u/Bob_X)\ **Post date:** [February 6, 2013, 5:09am UTC](https://boards.straightdope.com/t/size-of-individual-cells/649411/12 "2013-02-06T05:09:53Z")
> [@artemis](#): > > An unfertilized chicken egg is a single cell, and it’s clearly a much bigger cell than even the largest cell in a human body. Cells can vary enormously in size. There is a single cell INSIDE a chicken egg. Most of the egg is no part of the cell. ---
**Author:** ![Sailboat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sailboat/32/461_2.png) [@Sailboat](https://boards.straightdope.com/u/Sailboat)\ **Post date:** [February 6, 2013, 1:48pm UTC](https://boards.straightdope.com/t/size-of-individual-cells/649411/13 "2013-02-06T13:48:52Z")
I’ll admit to being surprised **eltro102** did turn out to have a citation for that. 🙂 > [@eltro102](#): > > They haven’t actually found the DNA, but they have looked at the cell sizes, from which they know the properties of the nucleus, from which they can get that they had large DNA to fit into the nucleus, there a number of articles on this on the internet but they all reference [this](http://www.nature.com/nature/journal/v446/n7132/abs/nature05621.html)paper My confusion stemmed from the current understanding that birds are dinosaurs, so we could in theory look at bird nuclei to answer questions about dino nuclei. However, the abstract from the paper is pretty confusing to me: > [@](#): > > Avian genomes are small and streamlined compared with those of other amniotes by virtue of having fewer repetitive elements and less non-coding DNA1, 2. This condition has been suggested to represent a key adaptation for flight in birds, by reducing the metabolic costs associated with having large genome and cell sizes3, 4. However, the evolution of genome architecture in birds, or any other lineage, is difficult to study because genomic information is often absent for long-extinct relatives. Here we use a novel bayesian comparative method to show that bone-cell size correlates well with genome size in extant vertebrates, and hence use this relationship to estimate the genome sizes of 31 species of extinct dinosaur, including several species of extinct birds. Our results indicate that the small genomes typically associated with avian flight evolved in the saurischian dinosaur lineage between 230 and 250 million years ago, long before this lineage gave rise to the first birds. By comparison, ornithischian dinosaurs are inferred to have had much larger genomes, which were probably typical for ancestral Dinosauria. Aside from the usual confusion caused by the apparent fact that birds do not come from the ornithischian (“bird-hipped”) dinosaurs, what baffles me is the idea that the bone cells in the saurischian dinosaurs were supposedly unusually small; those animals included the largest land animals ever known. I’m also shocked to see that the differences between the saurischian and ornithischian lines go all the way down to the cellular level; that seems like too fundamental a thing to vary among lineages so similar and so related.