Peroxisome in Animal Cell

In a cell cycle, there are specific checkpoints between each phases caused by the occurrence of cyclin. Cyclin determines how concentration flunctuatues. If the regulation is disrupted by a decreasein cyclin, there would be no mitosis, meaning the cell cycle would continuously go thre G0 phase. However, if there is an increase

Interphase: This particular stage is divided into three phases, G1 (first gap), S (synthesis), and G2 (second gap). During all three phases, the cell grows by producing proteins and other organelles within the cytoplasm. However, chromosomes are replicated only during the S phase. In all, a cell grows (G1), continues to grow as it duplicates its

“Peroxisomes are so named because they usually contain enzymes that use oxygen to remove hydrogen atoms from specific substrates in an oxidative reaction that produces hydrogen peroxide (H2O2) (McCance & Huether, pg. 7).

Without cell division and the cell cycle nearly all life would fail to exist. Cell division allows an organism to not only replace its own cells but to create offspring. The cell cycle consists of two main parts: interphase and mitotic phase. Within these two phases the processes can be broken down into further categories. Interphase can be broken down into three subphases that are the necessary preparations the cell makes in order to be ready to divide during mitosis. For this lab we looked mainly at the mitotic phase because of its fascinating and rapid changes to the cell. The cell types we looked at were prepared slides of whitefish and onion root tip.

With all living organisms, a process known as cell respiration is integral in order to provide the body with an essential form of energy, adenosine triphosphate (ATP). Oxygen, although an essential part of this process, can form reactants from colliding with electrons associated with carrier molecules. (pb101.rcsb.org, 2017). Hydrogen peroxide is an integral product of this reaction but is known to impose negative effects on the body if high levels are introduced. Explicitly, this reaction is caused “If oxygen runs into (one of these) carrier molecules, the electron may be accidentally transferred to it. This converts oxygen into dangerous compounds such as superoxide radicals and hydrogen peroxide, which can attack the delicate sulphur atoms and metal ions in proteins.” (pdbh101.rcb.org, 2017). Research has suggested that the hydrogen peroxide can be converted into hydroxyl radicals, known to mutate DNA, which can potentially cause bodily harm due to DNA’s role in the synthesis of proteins. These radicals can cause detrimental effects on the human body, and studies have suggested a link to ageing. Due to the harmful effects of these H2o2, it is important that the body finds a way to dispose of hydrogen peroxide before concentrations are too great.

Mitosis is the process of duplicating nuclear material one cell becomes two cells. A cell contains 46 chromosomes, this is known as diploid. This process involves prophase, metaphase, anaphase, and telophase. Mitosis ensures the continuation of the organism and helps the body build and repair. Meiosis on the other hand is for production of haploid cells, 23 chromosomes, that together with another human, new organisms are created.

17) The process by which the cytoplasm of a eukaryotic cell divides to produce two cells is called

Mitosis is one of two main methods of cell replication, the other being meiosis. It is “the simple duplication of a cell and all of its parts” resulting from the splitting of a cell. The ‘parent’ or original cell splits, duplicating its DNA (packaged in chromosomes) producing two ‘daughter’ or new cells with the same genetic code. There are four stages of mitosis; Prophase, Metaphase, Anaphase and Telophase. Interphase is not an official phase of mitosis as the cell is at ‘rest’ and not being divided during this phase. It is often called one of the phases of mitosis as it is one of the stages in the life cycle of a cell; however it is not a phase of mitosis due to the fact that no division takes place.

periods in cultures and can be manipulated and transformed into any type of cell in the

PKU, also known as Phenylketonuria, is a genetic disorder that builds up the amino acid phenylalanine in the human body. This genetic disorder is known to be an example of the norm of reaction. The norm of reaction defines itself as a phenotype range that a person with a certain genotype reveals due to the differing of a certain environmental condition. Since this genetic mutation targeted the gene that encrypts the enzyme phenylalanine hydroxylase, it shows that if a person has one and/or two copies of that certain gene, that person would have the ability to eat and metabolize foods with phenylalanine. But, if a person has two copies of the mutated gene, they wouldn’t be able to eat nor metabolize foods with phenylalanine because if a person with PKU were to ingest foods with phenylalanine, the amino acid will accumulate in their body and become highly toxic to the person and the PKU homozygotes will lead to an assortment of detrimental symptoms, which currently occurs in about 1 in 10,000 babies.

A dysfunction of an enzyme in the peroxisome leads to the accumulation of very long-chain fatty acids (VLCFA) in several areas (several areas of what?) including the central nervous tissue(CNS). The accumulation of VLCFA is toxic leading to the death of neuroglial cells like the oligodendrocytes and astrocytes. Astrocytes in normal conditions regulate the composition of the blood-barrier in the central nervous system; The olygodendorocytes form the myelin sheath that covers the axons and facilitate the effective propagation of action terminals from the neuron to the target cells (Amerman 390). This disorder (what disorder) is caused by a mutation in the ABCD1 gene of the X-chromosome, it causes the demyelination of the neurons in the CNS inhibiting the integration of the information from sensory stimuli and the proper response to them, causing eventually death. X-linked disorders are present are a wide variety of phenotypes, CCALD is the most common and presents only on boys between the age of 4 and 12. CCALD is a rapidly progressive disease, its deteriorates the patient health in a matter of years, and due to its complexity, its commonly misdiagnosed (Engelen).

• Describe the changes that occur inside the cells as a result of alterations in the amount of calcium in the cytoplasm. What effect will this have on the cells?

Because peroxisomes play a significant role in cell, the deficiency of peroxisomes are dangerous. One of the most life-threatening diseases which are caused by the absence of peroxisomes is Zellweger syndrome. This condition is also called peroxisome deficiency disorders. In the patients with Zellweger syndrome, there are mutations in PEX genes which encoded for peroxisome assembly. Because peroxisomes help cell oxidize the long chain fatty acids, these patients can not oxidize fatty acids and build up bile acid precursors. As a result, the symptoms or peroxisome deficiency disorder are neonatl hypotonia, neurological manifestations such as psychological and motor retardation, seizures; liver diseases such as cirrhosis, hepatomegaly… The outcome of this disease is poor. There are many infants die in the first year of life because of respiratory compromise from

The remaining cases are caused by mutations in a gene called PEX7 (deficiency of the PTS2 receptor). The Refsum disease phenotype caused by pathogenic variants in PEX7 may be milder [van den Brink et al 2003b=van den Brink DM, Brites P, Haasjes J, Wierzbicki AS, Mitchell J, Lambert-Hamill M, de Belleroche J, Jansen GA, Waterham HR, Wanders RJ. Identification of PEX7 as the second gene involved in Refsum disease. Adv Exp Med Biol. 2003b;544:69–70.]. Mutations in either the PHYH or PEX7 gene disrupt the usual functions of peroxisomes, including the breakdown of phytanic acid, which builds up in the body's tissues. The accumulation of phytanic acid in the body’s tissue is toxic to cells, although it is unclear how an excess of this substance affects vision and smell and causes other specific features of Refsum

The main focus of this lab was to be able to understand the different phases of mitosis and the cell cycle and also identify what those stages may look like. Mitosis is the process in which concerns the production of new cells. For example, when apoptosis(cell death) the process of Mitosis begins to replace the dead cells. To be able to familiarize ourselves with this concept, we took a sample of an onion root and had it put through a process to be able to look at the different phases under the microscope. We found that the majority of the cells were mostly undergoing Interphase or Prophase which are the phases in charge of crossing over of DNA and where the chromosomes then become visible and the nuclear envelope dissipates. The conclusion of this lab was that Mitosis is essential for the production of new cells. In the case of the onion root sample, the cells were damaged leading to the tester to undergo Mitotic cell division and it was found that mainly Interphase and Prophase were the stages that occurred in this lab.