Distribution of isotopes throughout the body

[Loren Booda]

Are different carbon, e. g., isotopes distributed throughout the human body in relatively different concentrations? Are radioactive atoms mutagenic and electronically dissimiliar, thus affecting the chemistry of neighboring structures? Could these isotopes be a considerable source of DNA diversity?

 

[Ouabache]

Natural Radioactivity in the Body

There is natural background radioactive isotopes in our body.
Natural Radioactivity in the Body ( http://www.doh.wa.gov/ehp/rp/air/factsheets-htm/FactSht10.htm )

Small traces of many naturally occurring radioactive materials are present in the human body. These come mainly from naturally occurring radioactive nuclides present in the food we eat and in the air we breathe. These isotopes include tritium (3H), carbon-14 (14C), and potassium-40 (40K). About 11% (40 mrem) of our radiation dose comes from naturally occurring radioactive materials in the body. Most of the dose comes from a radioactive isotope of potassium. Radioactive potassium-40, as well as other radioactive materials (such as carbon-14) which occur naturally in air, water, and soil, are incorporated into the food we eat and then into our body tissues.

 

[Loren Booda]

I wonder if the net radiation from the human body compares to that impinging upon it from the exterior environment?

 

[Mattara]

Are different carbon, e. g., isotopes distributed throughout the human body in relatively different concentrations?

What do you mean by this? If different isotopes are in different concentrations in different places in the body? Can you please clarify?

Are radioactive atoms mutagenic and electronically dissimiliar, thus affecting the chemistry of neighboring structures?

Yes, mutations can occur by radiation, but only in relatively large quantities. The normal background radiation is much much more stronger than any radiation that come from naturally occurring elements, that you would normally take in. Even radiation from future fusion plants would be about 1% of the current background radiation.

However, if you eat a kilogram of weapongrade uranium U-235 you would indeed be subjected to..well...death.

Could these isotopes be a considerable source of DNA diversity?

As a result, no.

 

[daveb]

Depending upon where you live, about 5/6 of your roughly 360 mrem background exposure comes from natural sources, and about 200 mrem of this comes from radon.

 

[Loren Booda]

Mattara

What do you mean by this? If different isotopes are in different concentrations in different places in the body? Can you please clarify?

For instance, in the evolution of grasses first one isotope of carbon (designated C₃) was common, then another (C₄). I thought that different isotopes in general might perform different functions in human tissue or DNA as well.

 

[iansmith]

MattaraFor instance, in the evolution of grasses first one isotope of carbon (designated C₃) was common, then another (C₄). I thought that different isotopes in general might perform different functions in human tissue or DNA as well.

C₃ and C₄ are not isotope. These refers to the amount of carbon on the sugar synthesized by the plant.

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/C4plants.html

 

[daveb]

MattaraFor instance, in the evolution of grasses first one isotope of carbon (designated C₃) was common, then another (C₄). I thought that different isotopes in general might perform different functions in human tissue or DNA as well.

Plus, different isotopes are chemically identical, that is, a radioactive C14 atom is no different for chemical reactions than a non-radioactive carbon atom. Chemical behavior is determined primarily by the electrons in the outer shell, which is why elements are divided into periods.

 

[Mattara]

MattaraFor instance, in the evolution of grasses first one isotope of carbon (designated C₃) was common, then another (C₄). I thought that different isotopes in general might perform different functions in human tissue or DNA as well.

Besides, Carbon-14 decay is only for beta radiation (and not gamma which would have any effect at all).

 

[Loren Booda]

If you all have the opportunity, see the bottom half of page 230 in the popular (and scientific) book "Beasts of Eden," about mammal evolution. Its author, David Rains Wallace, seems to have made a major gaffe with the term "isotope" in reference to carbon in grasses.

Aside: I believe that deuterium may have significant chemical differences with common hydrogen.

 

[dav2008]

If you all have the opportunity, see the bottom half of page 230 in the popular (and scientific) book "Beasts of Eden," about mammal evolution. Its author, David Rains Wallace, seems to have made a major gaffe with the term "isotope" in reference to carbon in grasses.

Aside: I believe that deuterium may have significant chemical differences with common hydrogen.

The chemical properties should be identical. The thing that contributes to their difference is that Deuterium has a larger mass so, for example, reactions involving Deuterium might proceed at a slower rate than those involving Hydrogen.

 

[Bystander]

http://www.biologie.uni-hamburg.de/b-online/e24/24b.htm

Isotope effects: compounds containing lighter isotopes exhibit slightly higher rate constants in chemical reactions; that is, ¹²C, ¹³C, and ¹⁴C abundances (measured in ppm enrichments or depletions of ¹³C, and ¹⁴C) differ in bio-mass from those of C from other sources.

 

[Loren Booda]

Thanks all for your addenda.

I figure that C₃ and C₄ are actually isomers of molecular carbon, whence a misprint by "Beasts of Eden."

 

[nipwoni]

They're not isomers either. C3 plants initially incorporate carbon into a 3-carbon molecule, while C4 plants incorporate it into a 4-carbon molecule. There are also many other anatomical and physiological differences between the two types of plants.

 

[Loren Booda]

Looks like you have the definitive answer, nipwoni.