Dictionary » M » Molecule



noun, plural: molecules

A tiny or a very small piece (of something).

(biology or biochemistry) An extremely small particle or substance, especially at cellular or structural level, as a biomolecule.

(physics and chemistry) The smallest unit of an element or compound, made up of two or more atoms held together by strong chemical bond.


In physics and chemistry, a molecule is an electrically neutral, group of atoms that can exist alone in free state while its characteristic properties are retained. The atoms comprising the molecule may be of the same kind (as in oxygen molecule made up of two oxygen atoms) or of different kinds (such as water molecule made up of oxygen and hydrogen).

In biology, particularly in biochemistry, a molecule is used less strictly that it can also refer to any minute particle such as charged organic molecules or to substances (called biomolecules) produced and occur naturally in living organisms such as proteins, carbohydrates, DNA, etc.

Word origin: French molécule, from New Latin mōlēcula, diminutive of Latin mōlēs, mass.
Related forms: molecular (adjective)

Related terms:

Please contribute to this project, if you have more information about this term feel free to edit this page

Results from our forum

Electron transport chain

And they are passed from one molecule to other in close proximity, so the chance of going elsewhere is probably low.

See entire post
by JackBean
Wed Jun 25, 2014 12:20 pm
Forum: Cell Biology
Topic: Electron transport chain
Replies: 3
Views: 515

Re: 2.5 M glycine crystallized

It's normal for some things to crystallize out of aqueous solution, especially at reduced temperatures. Apparently glycine is such a molecule. Storage at room temperature might prevent the crystallization, but you might also get microbial growth if there are any critters in there. Try gently ...

See entire post
by jonmoulton
Fri Jun 20, 2014 2:45 pm
Forum: Molecular Biology
Topic: 2.5 M glycine crystallized
Replies: 1
Views: 456

How did endosymbionts coordinate replication?

Another question about mtDNA: what is the advantage to/role of having multiple copies of the same circular DNA molecule? Isn't that "too much of a dose" of the same given gene? Any mitochondria expert out here?

See entire post
by kk
Fri Jun 06, 2014 12:16 pm
Forum: Cell Biology
Topic: How did endosymbionts coordinate replication?
Replies: 9
Views: 4099


how does the size of a molecule affect the rate of diffusion. I am confused how this works. any help would be appreciated.

See entire post
by kristenb
Fri Apr 04, 2014 6:12 am
Forum: Cell Biology
Topic: diffusion
Replies: 2
Views: 667


usually 1 nm and higher. Size of atoms (C, N) is 70 pm and smaller. That's 20-times less. However, you may be interested in the new one-molecule sequencing methods. And separation of chromosomes by dissection by laser is also nothing new. This is not a problem again. After scanning slices ...

See entire post
by enarees
Wed Feb 26, 2014 6:57 pm
Forum: Microbiology
Topic: Slicing frozen chromosomes with lasers and scanning with SEM
Replies: 4
Views: 1485
View all matching forum results

This page was last modified 09:54, 19 February 2009. This page has been accessed 75,935 times. 
What links here | Related changes | Permanent link