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In osteology, the osteon or haversian system (/ h ə ˈ v ɜːr. ʒ ən /; named for Clopton Havers) is the fundamental functional unit of much compact bone. Osteons are roughly cylindrical structures that are typically between 0.25 mm and 0.35 mm in diameter . [ 1 ]
Human bones are densely vascularized as in many other mammals. Even though some authors tried to identify a correlation between endothermy and secondary Haversian reconstruction, this feature is absent in many living mammals (e.g. monotremes, Talpa, flying foxes, Herpestes, Dasypus) and birds (Aratinga, Morococcyx, Nyctidromus, Momotus, Chloroceryle) while others possess only scattered ...
This gene encodes an isoform of the alpha subunit of the elongation factor-1 complex, which is responsible for the enzymatic delivery of aminoacyl tRNAs to the ribosome. This isoform (alpha 1) is expressed in brain, placenta, lung, liver, kidney, and pancreas, and the other isoform (alpha 2) is expressed in brain, heart and skeletal muscle.
Within chromosomes, DNA is held in complexes with structural proteins. These proteins organize the DNA into a compact structure called chromatin. In eukaryotes, this structure involves DNA binding to a complex of small basic proteins called histones, while in prokaryotes multiple types of proteins are involved.
The skeleton, often referred to as the skeletal system, is important both as a supporting structure and for maintenance of calcium, phosphate, and acid-base status in the whole organism. [5] The functional part of bone, the bone matrix, is entirely extracellular. The bone matrix consists of protein and mineral. The protein forms the organic matrix.
Bone canaliculi are microscopic canals between the lacunae of ossified bone.The radiating processes of the osteocytes (called filopodia) project into these canals. These cytoplasmic processes are joined together by gap junctions.
Gene structure is the organisation of specialised sequence elements within a gene. Genes contain most of the information necessary for living cells to survive and reproduce. [ 1 ] [ 2 ] In most organisms, genes are made of DNA, where the particular DNA sequence determines the function of the gene.
This gene is responsible for encoding the protein huntingtin which plays a role in preventing apoptosis, [31] otherwise known as cell death, and repair of oxidative DNA damage. [32] In Huntington's disease the expansion of the trinucleotide sequence CAG encodes for a mutant huntingtin protein with an expanded polyglutamine domain. [ 33 ]