List and briefly explain the two main mechanisms by which mammalian genes can be exchanged or 'translocated' between chromosomes. What are the importance of these types of recombination? (8 marks)

i. Homologous Recombination. A conservative, error-free DNA replication pathway that mainly allows for the repair of DNA under duress and also for the resetting of replication forks. The pathway is regulated by typical restriction endonuclease to 'cut' the DNA at appropriately designated sites or 'cleavage points' of high AT content percentage DNA at their hydrogen bonds, and ligase enzymes (which are more generic) to reseal complimentary base pairs of similar, 'sticky' ends via hydrogen bond formation. Homologous Recombination can occur throughout mitosis and is a source of genetic diversity within mature organisms; if chromatin affecting, these can become hereditary mutations though they're more frequently for within lifetime adaptations.ii. Non-homologous Recombination. A similarly conserved mechanism involving restriction endonucleases and ligase enzymes, the key difference is that non-homologous recombination is guaranteed with each meiotic division; it is a key evolutionary mechanism to invite resulting germ line cells with genetic diversity. This kind of recombination involves 'crossing over' of sister chromatids at like-points via binding to the chiasmata. This is important as it occurs both within the initial diploid cells before meiotic division, and again at fertilisation when the zygote is formed as diploid and the two nuclei fuse. Simply put, this is a key mechanism for evolution and maintaining and developing reaistance/ adaptations to survival pressures. Unlike homologous recombination, large base pair sequences can be translocated between non sister chromatids and even entire chromosomes via translocation machinery located within the meiotic spindle, it is the greatest natural source of large scale genetic variety and mutation.