Autophagy is the process of the catabolic breakdown of unnecessary or dysfunctional cellular components or involves cell degradation through the mechanism that involves lysosomes28. Autophagy is involved in many different cellular programs, and it is primarily involved in the degradation, synthesis and recycling of different cellular components in the cell28. Breaking down cellular components can be of great importance to ensure cellular survival during stress inducing mechanisms such as starvation by maintaining the necessary energy levels28. For our next experiment we believed that inducing autophagy by treating the cells for two hours with Earle’s Balanced Salt Solution which contains an extremely low concentration of essential amino acids will induce pausing of ribosomes at essential amino acids. We will compare these results with a control treatment where the inhibitor of translation, Torin-1, is used to treat the cells for two hours to truly observe the effect of pausing caused by autophagy and not affected by reduction of protein synthesis (Figure 5). As is shown in figure ...
Lysosomes contain hydrolytic enzymes which function in the acid of the lysosome and are meant to be secreted not as wastes into the extracellular fluids, but as secretory proteins into an intracellular organelle. When one of these enzymes is dysfunctional, the catabolism of its macromolecule does not completely occur and there is a buildup of the macromolecule inside the lysosome. This results in great numbers of large lysosomes which begin to interfere with the normal functions of the cell. This disorder is called lysosomal storage disorder. These disorders can eventually lead to the dysfunction of the organs. The organs affected by the disorder are determined by two factors: 1) The location in the body where the macromolecules that are to be catabolized are found, and 2) The location where the catabolism occurs.
Glycation is a natural chemical reaction in the body that involves combining sugar molecules to protein molecules without the help of enzymes. In contrast to similar a chemical reaction that involves enzyme-directed processes called glycosylation, glycation disrupts normal metabolic pathways. This results in the production of advanced glycation end products (AGEs), which are assocated with oxidative damage that leads to pathological changes in various organ systems.
The effects of RNAi can be contrary to chromatin and DNA modifications in mediating mRNA degradation, inhibition of translation, DNA elimination and similar in heterchromatin formation.
In a healthy and young body, both antioxidants and the cell’s own repair capabilities work together to keep the cell intact. However, if the cell has become way too damaged for quite some time and cannot manage all the lesions created by free radicals, it can lose its ability to deal with the damages. This can also be referred to as the oxidative stress that the cells incur. Thus, they die quickly or begin replicating their damaged forms, and create a domino effect of the body gradually not being able to continue maintaining proper functioning
During this phase, the cell takes in nutrients and builds proteins that are used by the cell for energy
By utilizing the model yeast S. cerevisiae, Ohsumi found a method for identifying the ATG genes. Ohsumi blocked vacuolar degradation using the yeast mutants, then induced autophagy by starving the cells. With the vacuole impaired, the autophagosomes accumulated in the cell, allowing researchers to simply visualize these compartments, which are generally quite difficult to identify. Ultimately, this technique allowed for the discovery of autophagy genes and mechanisms. (4) This concluded the discovery of the first genes necessary for autophagy. The results displayed that autophagy is controlled by a number of proteins and protein complexes which promote a specific stage of the formation of autophagosomes.
46- Kozak M. Rethinking some mechanisms invoked to explain translational regulation in eukaryotes. Gene. 2006; 382: 1-11.
The paper, Function of Aggregated Reticulocyte Ribosomes in Protein Synthesis by A. Gierer, details the findings about a study to answer the question whether multiple ribosomes can operate on one molecule of messenger RNA simultaneously. Firstly, background information is necessary for understanding this paper. Ribosomes, the organelle where protein synthesis occurs, require a messenger RNA to be attached to it to be labelled active. Active ribosomes have an increased molecular weight due to the mRNA which in turn causes a higher sedimentation coefficient. The value of the sedimentation coefficient is calculated by timing the movement of a particle in a medium of known viscosity.
Well, throughout apoptosis cells undergo a life cycle. Throughout this cycle, cells undergo a programmed cell death, or “cellular suicide” when they receive certain cues. The process of apoptosis is quite simple. First, the cells shrink and develop blebs on their surface. The DNA in the nucleus gets chopped up into small pieces, and some organelles of the cell break down into fragments. The entire cell splits up into small chunks, each neatly enclosed in a package of membrane. The chunks then release signals that attract phagocytic debris-eating cells. In addition, some chunks display a lipid molecule called phosphatidylserine on their surface. It then lets the phagocytes bind and eat the cell fragments. Obviously the apoptosis process plays an incredibly crucial role in cell death, as it controls how humans stop growing, when we are producing millions of cells every second. The process of apoptosis has a very effective, yet simple cycle which recycles cells, in the end maintaining the number of cells in a
Senescence is the age-dependent deterioration process at the cellular, tissue, organ, or organismal level, leading to death or the end of the life span (Nooden, 1988). Leaf senescence is an organ level senescence but is often intimately associated with cellular or organismal death (Lim et al., 2007). According to Betania et al. (2000), it is the last stage of leaf development. The senescence process is started by the breakdown of chloroplast (Gepstein, 2004). Next, it is followed by macromolecules catabolism for example nucleic acids, proteins, and lipids (Ulker et al., 1997). Final stage for leaf senescence is the degradation of mitochondria and nuclei (Gan and Amasino, 1997; Lim et al., 2007). Nutrients released by leaf senescence for example nitrogen, phosphorus, and minerals will be invested to younger leaves and growing seeds, or are stored for the next growing season and it can be viewed that as a recycling program at the organismal level (Betania et al., 2000).
This causes the breakdown of phospholipids, proteins, and lipids, ultimately pushing a self-destruction button on biological membranes. Scar tissue results after inflammatory reactions act to remove the debris that is left behind. While TBI may cause cell death in the form of necrosis, it may also cause programmed cell death, or apoptosis. Neurons that are affected by this kind of automated destruction are physically unabridged at the beginning stage of injury and are reasonably functional, but the effects of injury are seen several hours or days after the primary event. Membrane deterioration, including nuclear membrane lysis, and DNA fragmentation take place, with apoptotic bodies cleaning up the subsequent rubble. As a result of the delayed action of apoptosis, it presents great potential for therapeutic
Fermentation is an anaerobic process in which fuel molecules are broken down to create pyruvate and ATP molecules (Alberts, 1998). Both pyruvate and ATP are major energy sources used by the cell to do a variety of things. For example, ATP is used in cell division to divide the chromosomes (Alberts, 1998).
Glycolysis means "splitting sugars" and it is a process that release energy present within sugars. In glycolysis, glucose a six carbon sugar is split into the two molecules of the three-carbon sugar called pyruvate. It is a multi-step process that yields two molecules of ATP, two "high energy" electron carrying molecules of NADH and two molecules of pyruvate. The process of glycolysis can occur with or without oxygen. Glycolysis is the first stage of cellular respiration in the presence of oxygen while in the absence of oxygen, glycolysis allows the cells to make little amount of ATP through the process called fermentation [Bailey, Regina. "10 Steps of Glycolysis"].
Cell death restrains the superfluity of physiological processes such as embryogenesis, post-embryonic development (Penaloza et al, 2006) and tissue homeostasis and abrogating cell death provokes various diseases such as autoimmune diseases and cancers. (Galluzzi, Maiuri et al. 2007) In the long time of cell death related studies researcher have found dozens of methods to study the death related parameters but none of these method fulfill the requirement. NCCD (Nomenclature Committee on Cell Death) assigned some features for a cell known to be dead which includes. 1) Loss of plasma membrane integrity. 2) Complete destruction of the cell as well as its nucleus. 3) Engulfment of its fractions by neighboring macrophages in vivo. Cell death can be divided into various categories based on morphological appearance (apoptosis, autophagy, necrosis and mitosis associated cell death), enzymatic (with and without involving crucial enzymes such as nucleases, and proteases such as caspases or cathepsins), functional prospects (Physiological or pathological, programmed or accidental) or finally immunologic or non-immunogenic. (Kroemer, Galluzzi et al. 2009).