Conjugation

A form of a verb that relates to the tense of the sentence, or the process of creating that form of the verb.

The english language doesn't have as much conjugating to do as other languages, especially latin.

An example by conjugating the verb taste:

She tasted.
She tastes.
She's tasting.
She will taste.

Webster's definition 3c for conjugation is a pretty important one.

In English there is effectively one conjugation of verbs, with some slight variations: talk, talks, talking, talked. Even the majority of irregular or strong verbs have at most one more case than this, having different imperfect and perfect parts: tread, treads, treading, trod, trodden. The -en ending is a residue of a lost class of regular verbs with -en endings.

French has three regular conjugations: the -er class, the -re class and the -ir class. French verb conjugations will be noded separately.

N-Wing informs me that Spanish has three regular conjugations, with endings -ar, -er and -ir. Spanish verb conjugations may be noded separately.

Swedish has four main conjugations, all of them regular, three weak and one strong. The strong conjugation, usually called the fourth, has a number of different varieties in the past tenses, while the weak second conjugation has two subclasses. Swedish verb conjugations will be noded separately.

Latin also has four main conjugations, of which the third closely resembles the behaviour of Germanic strong verbs, and is only semi-regular. Certain fourth-conjugation verbs resemble those of the third. Latin verb conjugations will be noded separately.

Bacterial conjugation involves a RecA independent transfer of a single strand of DNA from doner to recipiant, generally via a sex pilus. The F plasmid is the best characterised example of this, but other plasmids are also capable of conjugation. In order for conjugation to be possible, two things must be present - a mechanism for the transfer of the DNA (the tra region on the F plasmid) and somewhere for the plasmid to be nicked and transfer to initiate (the OriT region on the F plasmid). There is no requirement for both of these to be on the same plasmid, although in the case of F they are.

Carrying the F plasmid causes the host bacterium to express the tra genes, one of which (traA) causes assembly of a sex pilus on the outside of the bacterium. If this pilus comes into contact with a bacterium not carrying the F plasmid (the traS and traT genes cause production of coat proteins that prevent sex pili from attaching), the two bacteria are drawn together and a pore opened between them. The OriT region of the F plasmid is nicked and rolling circle replication used to displace one strand. The displaced strand is guided through the pore by other tra genes and transferred to the recipient. Once there, the ends of the single strand are ligated and a new strand produced to bring it back to the double stranded state.

Conjugation is not limited to plasmids. The F plasmid is capable of recombining itself into the bacterial chromosome. Once there, the chromosome itself can be transferred. Usually the bacteria will drift apart before the entire chromosome can be transferred (conjugation is fairly slow. This is also true when it occurs in language classes. A-ha ha ha. Sorry.), so you can get some idea of how far apart two markers are by looking at the frequencies of co-conjugation. If a chromosome is copied, the high degree of homology with the recipient chromosome means that recombination is quite likely.

The idea of F+ and F- being analagous to male and female is only accurate if you don't object to the fact that in this analogy, women who consent to sex turn into men afterwards. Being F+ is not necessarily advantageous - the extra coat proteins produced make the bacterium in question more susceptible to bacteriophage infection, which is probably why F plasmids are not ubiquitous.

(group theory)

Definition : Let G be a group and g and x elements in it. Then the conjugate of g by x, often written g^x, is xgx^-1. Can also be defined as x^-1gx - it doesn't really make much of a difference.

Although everything we can prove about conjugation applies generally, a nice way of looking at conjugation comes from the case of G acting on a set Ω. So here x and g are actions, be they rotations or permutations or whatever, and we see that g^x is the action of doing x, doing g, and then undoing x. So we're moving whatever we're acting on into some state, doing g, and then moving it back into what would be the original state except had we not done g in between. So anything (any element of Ω) which g leaves alone in that moved state is going to return to where it was unchanged, and in general we can see that g and g^x are going to look very much alike.

The basic point is that g^x "does the same thing" as g, but it does it to different elements of Ω - in particular to those which x puts (in the finite case, permutes) into the positions which g acts on. So (in the group of linear transformations of Euclidean space) the conjugate of a rotation will be a rotation, and (in the group of moves on a Rubik's cube) the conjugate of a double corner swap will be a double corner swap.

This is a consequence of the more abstract fact that conjugation by a fixed element x is an automorphism, i.e. an isomorphism from G onto itself. The proof is straightforward from the definition.

Much more can be said about conjugation, but I'll constrain this write-up to the following. Firstly, note that g¹ = 1g1^-1 = g and g^xy xyg(xy)^-1 = xygy^-1x^-1 = (g^y)^x, so conjugation satisfies the axioms for an action of G on itself. And hence G partitions into orbits - the conjugacy classes of G. And by the theorem in coset space, we have that the conjugacy class of which an element g is a member, Orb(g), is isomorphic to (G : Stab(g)) - the coset space of Stab(g) in G. With the action of conjugation, the stabilizer Stab(g) is also known as the centralizer of g, and consists of the elements of G which commute with g (since xgx^-1 = g <==> xg = gx).

So we have that the structure of a conjugacy class is the same as that of the set of cosets of the elements which commute with any fixed element of the conjugacy class, and hence also that those coset spaces are all isomorphic to each other - and in particular have the same size. And so by Lagrange's theorem, we have the (not immediately obvious) result that the centralizers of elements of a conjugacy class have the same size(/cardinality - all this applies to infinite groups as well as finite ones).

Con`ju*ga"tion (?), n. [L. conjugatio conjugation (in senses 1 & 3).]

1.

the act of uniting or combining; union; assemblage.

[Obs.]

Mixtures and conjugations of atoms. Bentley.

2.

Two things conjoined; a pair; a couple.

[Obs.]

The sixth conjugations or pair of nerves. Sir T. Browne.

3. Gram. (a)

The act of conjugating a verb or giving in order its various parts and inflections.

(b)

A scheme in which are arranged all the parts of a verb.

(c)

A class of verbs conjugated in the same manner.

4. Biol.

A kind of sexual union; -- applied to a blending of the contents of two or more cells or individuals in some plants and lower animals, by which new spores or germs are developed.

 

© Webster 1913.