Naked Science Forum

Life Sciences => Cells, Microbes & Viruses => Topic started by: colarris on 25/10/2019 16:14:45

Title: Are all of the body's different cell types nonetheless eukaryotic cells?
Post by: colarris on 25/10/2019 16:14:45
I have just started my journey into biology and have learnt about the Eurkaryote cells but then I have heard mention of different cells all over the body eg hair cells, skin cells etc. Are these all classed as Eurkaryote cells and are their make up the same??
Title: Re: Are all of the body's different cell types nonetheless eukaryotic cells?
Post by: evan_au on 25/10/2019 22:13:10
Human cells are all eukaryotes: cells where the DNA is enclosed in a special membrane.
- Some cells like hair, tonenails and skin cells are produced as living cells by the human body, but they act as a protective barrier. The cells die and are eventually shed, but they do contain DNA in a membrane when they form. Often human DNA can be recovered from hair on a hairbrush, for example.

See: https://en.wikipedia.org/wiki/Eukaryote

There are some cells in the human body which are prokaryotes, and have all their internal DNA and organelles floating around together. This is the bacteria and archaea which form part of our microbiome, living in our gut, for example.
See: https://en.wikipedia.org/wiki/Prokaryote
Title: Re: Are all of the body's different cell types nonetheless eukaryotic cells?
Post by: colarris on 26/10/2019 21:26:31
Appreciate the detailed answer, thank you.
Title: Re: Are all of the body's different cell types nonetheless eukaryotic cells?
Post by: Bored chemist on 27/10/2019 09:25:05
Are (my) red blood cells Eukaryotes ?
Come to think of it, are they alive?
They can't grow or reproduce.
Title: Re: Are all of the body's different cell types nonetheless eukaryotic cells?
Post by: evan_au on 27/10/2019 09:37:12
Quote from: boredchemist
Are (my) red blood cells Eukaryotes ?
Yes, in mammals, red blood cells start off as eukaryotes, with a nucleus.
But in the process of blood cell production, the daughter red blood cells end up without a nucleus (like platelets, another type of blood cell).

However, in birds and reptiles, red blood cells in circulation still have a nucleus.

See: How Red Blood Cells Nuke Their Nuclei (https://www.sciencedaily.com/releases/2008/02/080210145839.htm)

There are a few other specialised cell types in the human body with odd DNA - for example, liver cells have multiple copies of their DNA, and egg/sperm cells have a half-set of DNA.
Title: Re: Are all of the body's different cell types nonetheless eukaryotic cells?
Post by: colarris on 27/10/2019 23:03:15
Why the difference??
Title: Re: Are all of the body's different cell types nonetheless eukaryotic cells?
Post by: evan_au on 28/10/2019 09:40:45
It's very hard to definitively say "WHY" in biology, but there is no shortage of guesses...
- Red blood cells and platelets have to be very small, so a nucleus is just wasted space
- Red blood cells have to carry oxygen and carbon dioxide. DNA doesn't do this, so it's just wasted space
- DNA, ribosomes and mitochondria are a few of the complex cell components involved in a cell that is continually maintained, and actively responding to its environment; all this consumes energy. But if the required functions of a red blood cell (or a platelet) can be done just with proteins using much less energy, then why not make the red blood cell (and platelets) disposable?

Liver cells have to deal with toxins from the digestive system. As such, they are likely to suffer mutations and become cancerous. One way of avoiding cancer is to have multiple copies of a gene, so if one copy is damaged, other copies still continue making the required proteins. One way of having multiple copies of every gene is to have multiple copies of the DNA.
See: https://en.wikipedia.org/wiki/Hepatocyte#Microanatomy

Egg & sperm cells have half the number of chromosomes, so that when they meet, they can form a zygote with a full set of chromosomes (half from the mother, and half from the father).
See: https://en.wikipedia.org/wiki/Meiosis
Title: Re: Are all of the body's different cell types nonetheless eukaryotic cells?
Post by: colarris on 28/10/2019 17:15:26
Thanks you soo much for your detailed response, I appreciate it.