The first reaction occurs in the matrix of the mitochondria. The subsequent reactions occur in the cytosol. This is a pathway that lengths two cellular compartments. The first reaction is catalyzed by ornithine transcarbamoylase which transfers a carbamoyl group from carbamoyl phosphate to ornithine to form citrulline. The second reaction is catalyzed by argininosuccinate synthetase.
Fusion and Fission are both mediated by dynamin-related GTPases. Fusion is mediated by mitofusin 1 and mitofusin 2 on the outer mitochondrial membrane and by optic atrophy 1 on the inner membrane. While fission is mediated by dynamin related protein 1. Interestingly, neuromuscular disease in humans is observed when there are mutations of the mediator proteins. If mitochondrial fusion is blocked, purkinje neurons, responsible for motor coordination, degenerate in the cerebellum defaulting in defect in the electron transport chain and in mtDNA.
2006). Mitochondria has DNA, (mtDNA) which are not protected by the histones as in the nuclear DNA (Croteau and Bohr 1997). In the nuclear DNA, the histones offers a shielding to protect the DNA from damaging the free radicals (Milligan, Aguilera and Ward 1993), it is also required to repair the double stranded DNA breaks (Celeste, et al. 2003). The mitochondrial DNA on the other had is lacking the histones, hence
Shuttle mechanism in which the Fe (III) siderophore complex is transported across the cell membrane by siderophore specific transport proteins and the iron is reductively removed from the siderophore complex inside the cell (Helm & Winkelmann 1994). 2. Taxicab mechanism Fe (III) is transferred from extracellular siderophores to intracellular ligands across the cell membrane (Winkelmann and Huschka 1987). 3. Hydrolytic mechanism- Fe (III) siderophore is transferred inside the cell by
Recent studies using flow cytometry have demonstrated that light limitation and starvation induce phytoplankton cell arrest in G1. Photosynthesis is one of the major light dependent process which is affected the most by the fluctuation of light exposure. One key question with respect to the effect of light on the cell cycle concerns circadian rhythms. It is well known that phytoplankton division is synchronized to the light:dark cycle both in cultures and in the natural environment (Chisholm 1981). Many other cellular processes such as photosynthesis or gene expression are also synchronized.
HIFs are heterodimeric protein comprising of HIF-α subunits (i.e. HIF-1 α, HIF-2 α or HIF-3 α), and a constitutive HIF-1β subunit, it is also known as aryl hydrocarbon receptor nuclear translocator or ARNT, which together form the HIF-1, HIF-2 and HIF-3 transcriptional complexes, respectively . The purpose of this review to provides the brief overview about HIF transcription factor, its regulation in normoxic condition and hypoxic condition and the current trend in HIF system how to inhibit the protein-protein interaction in HIF
This can occur through vesicles that are formed by throttling the plasma membrane and then penetrating into the cell (endocytosis), or they merge with it to free their contents (exocytosis) outside. There are three types of endocytosis known: • phagocytosis - very common among unicellular protists, who use it to feed themselves; in the human body, some types of white blood cells incorporate cells and foreign substances into phagocytosis. • pinocytosis - a constant activity of pinocytosis is carried out by the endothelium, the tissue that covers the blood capillaries and which allows the cells of the surrounding tissues to withdraw fluids from the blood. • Receptor-mediated endocytosis - a quick and efficient method for withdrawing substances that can be found in the environment even at low concentrations. Finally, exocytosis is important for the secretion of many substances, including digestive enzymes produced by the pancreas and materials for the construction of the plant cell wall.
There are two separate clotting pathways, the intrinsic and the extrinsic. These eventually join together to form the common pathway. The adsorption of the components of the contact system facilitates the activation of the intrinsic pathway of coagulation. This results in the formation of thrombin which converts fibrinogen to fibrin monomers. The thrombin also promotes platelet aggregation.
However, each time a cell divides, some of the telomere is lost (usually 25-200 base pairs per division). When the telomere becomes too short, the chromosome reaches a "critical length" and can no longer replicate. This means that a cell becomes "old" and dies by a process called apoptosis. Telomere activity is controlled by two mechanisms: erosion and addition. Erosion, as mentioned, occurs each time a cell divides.
It also represents a cell death pathway characterized by specific features that differentiate autophagy from other cell death processes. The cells that are able to exert intense autophagic activity were also able to engulf and digest entire cell siblings. This phenomenon represents a sort of 'xeno-cannibalism'. The two phenomenon: Self and xeno-cannibalism, could be related; the latter being an exacerbation of the first and providing further survival option to the cells.