Clarifying distinction between genetic recombination , translocation. and transposition

Question

Having thought about the distinciton between these terms I have come up with the following definitions, are these correct?

Translocation describes the relocation of a chromosomal segment to a different position in the genome.

Recombination is the same except:

• it usually describes a non-pathological process involving balanced, reciprocal relocation of homologous DNA segments. Translocation is its accidental counterpart.
• Translocation usually related to endogenous DNA. Recombination is a broader term that can describe the incorporation of external DNA in bacteria such as transformation or transduction.
• The term can be used even more broadly to include independant assortment, which also effectivley acts to "Reshuffle" genetic material.

Transposition:

• essentially a special case of translocation which occurs as a result of transposase enzymes acting on mobile genetic elements.

Thanks for your help!

Answer 1

Translocation is a mutation . Others are not necessarily . By the way do not confuse those 3 terms with transversion and transition mutations.

Translocation refers to 2 concepts :

1. In protein localizing during/after transcription

wikipedia

article

2. A type of mutation in a chromosome

Chromosomal Translocation

(this is about the latter)

Translocation describes the relocation of a chromosomal segment to a different position in the genome.

To some extent yes. Also It is a type of mutation . It does not happen normally and it is a result of malfunctioning proteins, mutagens etc. More importantly Translocation happens

• a) between two nonhomologous chromosomes
• b) between one chromosome and itself (it moves to a different locus of the same chromosome)

See : Campbell biology 9th.ed.2011 Chapter 15 figure 15-14

you can say that Translocation of DNA segments between homologous chromosomes has a specific name ("duplication"). Keep in mind that most of the times we do not consider a movement of DNA to a homologous DNA a "translocation" as noted above.

Recombination is a new combination of 2 DNA . Two DNA s become one. I believe the difference between Translocation and Recombination is that Translocation usually involves a huge amount of DNA (a lot of genes) compared to Recombintation ( probably not more than 10 genes or so) I also agree with your statements on recombination. Here's more :

it usually describes a non-pathological process

Recombination happens in several ways. We have recombination resulted from DNA repair, recombination from Cross-over during meiosis, artificial lab DNA recombination (in vitro) and also recombination by some viruses during infection ( Recall Lysogenic cycles and retroviruses) or other vectors. Therefore recombination CAN happen in pathologic and non-pathologic procedures.

See: Molecular Cell Biology Lodish et al 8th ed Section 5.6 "DNA repair and Recombination" See T. L. Orr-Weaver and J. W. Szostak, 1985, Microbiol. Rev. 49:33.

Transposition: essentially a special case of translocation which occurs as a result of transposase enzymes acting on mobile genetic elements

Correct. Still I'm quite sure that we DO NOT use the term "Translocation" but instead "Recombination" for transposition.

a special case of Recombination which occurs as a result of transposase enzymes acting on mobile genetic elements.

Transposition involoves 2 or 3 genes and also it is not a type of mutation. So it is not a translocation.

See: Molecular Cell Biology Lodish et al 8th ed Section 8.3 "Transposable (Mobile) DNA Elements"