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)

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Re: Chromatin

Before replication there were 23 pairs of molecules, 23 of maternal origin and 23 of paternal origin, plus the maternally-contributed mitochondrial chromosome (which I'll ignore for the rest of this post). Counting chromosomal centromeres, there ...

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by jonmoulton
Thu Sep 04, 2014 3:04 pm
Forum: Genetics
Topic: Chromatin
Replies: 2
Views: 879

Chromosome Differences

I thing handling of large DNA molecule or chomosome may be difficult during replication or mitosis, so small DNA molecule selected during the course of evolution. We can see chromosomes number is usually increased from lower to higher eukaryotes ...

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by josem
Wed Sep 03, 2014 8:47 pm
Forum: Genetics
Topic: Chromosome Differences
Replies: 5
Views: 954

Re: Chromosome Differences

The DNA is never connected into a long single molecule in human cells. The DNA remains distributed into the 23 pairs of chromosomes (plus the mitochondrial chromosome), each single DNA molecules complexed with proteins. Each chromosome is replicated ...

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by jonmoulton
Wed Sep 03, 2014 3:06 pm
Forum: Genetics
Topic: Chromosome Differences
Replies: 5
Views: 954

Electron transport chain

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

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by JackBean
Wed Jun 25, 2014 12:20 pm
Forum: Cell Biology
Topic: Electron transport chain
Replies: 3
Views: 860

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 ...

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by jonmoulton
Fri Jun 20, 2014 2:45 pm
Forum: Molecular Biology
Topic: 2.5 M glycine crystallized
Replies: 1
Views: 861
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