Folic Acid an Example of the Topic Health Essays by

Folic Acid Folate, a water-soluble B-type vitamin which is synthesized as folic acid, helps in the maintenance of new cells. As such, the name, which is derived from a Latin word meaning leaf is a common sight in general health and medical literature concerning infancy and pregnancy, where the division and growth of cells is of crucial import. (Herbert, 1999) Need essay sample on "Folic Acid" topic? We will write a custom essay sample specifically for you Proceed Unsurprisingly, folates importance to cell division and growth is derived from its necessity to the production of DNA and RNA which are the core component of cells. Additionally, folate plays a role in regulation of cancer-inducing changes in DNA. (Fenech, et. al., 1998) Folate also plays a role in the metabolization of the amino acid known as homocysteine. (Kamen, 1997) Without folate, unchecked levels of homocysteine can lead to bone weakness and poses some cardiovascular risk. (Sato, et al; 2005) Still, this should not be misunderstood. Kaare Harald Bnaa, co-author of a report from the European Society of Cardiology, notes that based on results from the Norwegian Vitamin Trial, while folate does help lower the levels of homocysteine, it does not necessarily reduce the risk of heart failure. As such, high dose prescriptions of B-vitamins such as folate, do not prevent heart diseases and strokes, and are advisable only for patients suffering from B-vitamin deficiencies. (Bnaa, 2005) The recommended dietary intake for folate is set by the Institute of Medicine of the National Academy of Sciences (1998) at 400 micrograms per day for adults of both genders. For pregnant or lactating women, the recommended dietary intake for folate is 500 micrograms daily for those in the age range of 14-18, and 600 micrograms daily for those aged 19 and above. No recommended dietary intake has been sufficiently established for infants by the Institute of Medicine. However, they have approximated an adequate intake measure based on the amounts of folate consumed by healthy breast-fed infants. As such, the Institute of Medicine opines that 65 micrograms of folate is adequate for children up to 6 years old and 80 micrograms for children up to 12 years old. Incidentally, the Dietary Folate Equivalent of naturally occurring folate to synthetic folic acid derived from vitamin supplements and fortified foods. Effectively speaking, for every microgram of folate expressed in the recommended dietary intake, individuals may take 0.6 micrograms of folic acid from supplements and fortified foods instead. Undergraduates Frequently Tell EssayLab support:Who wants to write essay for me?Essay writer professionals propose: Essay Help Provided Here With Beneficial Facilities!Top Rated Essay Writing Service Write My Essay Online Writes Paper For You College Essay Writing Service Leafy vegetables such as lettuces, spinach and turnip greens are among the richest sources of folate, making it aptly the leaf vitamin. Other rich sources of folate include dried beans and peas and sunflower seeds. Many cereal products such as ready to eat whole grain cereals and white rice are also rich in folate, primarily due to having been artificially fortified with a quarter to a hundred per cent of the recommended dietary allowance for folic acid. Certain fruits such as oranges, tomatos, cantaloupes, papayas and bananas are also identified as rich sources of folate. (USDA, 2005) Much of the attention given to folate revolves around the link between folate deficiencies in pregnant women and neural tube defects in their children. As such, health watchdog groups and government health departments around the world have repeatedly recommended the use of supplements for the purposes of addressing these deficiencies. As implied above, this has led to many countries such as Indonesia, Mongolia and various Middle Eastern nations in addition to the United States introducing vitamin fortification of folate into various food commodities such as flour and cereal. The European Union stands as a notable exception in that the Food Standards Agency of the United Kingdom only recommends folate-fortification, whilst the remainder of the EU has, at present, not made fortification mandatory. (Russell, 2006) Gentili (2007) notes that the presence of folate is oft manifested in glutamate compounds which cannot be endogenously generated by the human physiognomy. The reason why folates manifest themselves in natural polyglutamate tissues is because it is a cell form that can sufficiently retain them. In terms of absorption and excretion, folates are metabolized into monoglutamates, which enable them to be transported across the human respiratory and excretory systems as plasma and urine. This metabolization occurs in the luman of the small intestine, where reside the enzymes that can convert the polyglutamate form of folates (i.e. food tissue) into the appropriate monoglutamate form. This monoglutamate form is then absorbed into the proximate area of the central small intestine or jejunum. Plasma-bound folate takes the form of 5-methyltetrahydrofolate or 5-methyl THFA, and is demethylated before it can be of any use to the human body in those enzymatic reactions which require folate. Incidentally, this is why excess or toxic levels of folate intake have been associated with Vitamin B-12 deficiencies. For consumed folic acid and folate to be properly metabolized into an excretable form, cobalamin or B-12 is required. Without B-12, folate cannot be rendered into an excretable form and remains bound as 5-methyl THFA. As such, regardless of the side effects of the folate itself, excess folate intake can result in severe B-12 deficiency and as a result leads to difficulty in metabolizing other vitamins, as well as megaloblastic anemia may occur, as well as neurological and psychiatric abnormalities resulting from this deficiency (Scott, 1999) As indicated above, many enzymatic reactions require folate acid, in its biologically active and metabolic form as THFA or demethyated tetrahyrofolic acid. This is because folate is necessary to the transfer of carbon units crucial to the synthesis of proteins and nucleic acids which form the base of DNA and RNA. (Fenech, et. al., 1998; Gentili, 2007) THFA also plays a necessary role in the synthesis of purine, thymidine and amino acid. From this, it is expected that folate deficiencies result in impairments in highly critical physiological functions: cell division, the impairment of methylatic reactions which regulate genetic expression. Hence, folate acid deficiency in pregnant women leads to severe developmental impairments in the prenatal infant. Mulenga, et. al. (2006) also report that despite the critical importance of folate to prenatal growth of infants, the use of high dose folic acid supplements interfere with anti-malarial treatment, specifically, sulfacoxine-pyrimethamine. This is a controversial point to consider, as while 4 micrograms of folate per day is adequate to protect against neural tube and brain defects in the developing fetus, women in sub-Saharan Africa, where the study was conducted, often take up to 5 milligrams a day because that this is the dosage at which folate supplements are available. The study reported that while there was no difference in stillbirths, premature deliveries and neonatal deaths among the subjects, treatment failure was double among those women taking the folate supplements than those taking placebos or 0.4 mg of folate. REFERENCES Herbert V. (1999). Folic Acid. Shils M, Olson J, Shike M, Ross AC, (Eds.). Nutrition in Health and Disease. Baltimore: Williams & Wilkins. Fenech, M; Aitken, C; Rinaldi, J; (1998) Folate, vitamin B12, homocysteine status and DNA damage in young Australian adults. Carcinogenesis 1998;19:1163-71 Kamen, B. (1997 Oct) Folate and antifolate pharmacology. Semin Oncol 1997; 24:S18-30-S18-39. Sato, Y; Honda, Y; Iwamoto, J; Kanoko, T; Satoh, K. (2005) Effect of Folate and Mecobalamin on Hip Fractures in Patients With Stroke. Journal of the American Medical Association 293: 1082-1088. Boona, K.H. (2005) NORVIT: Randomized trial of homocysteine-lowering with B-vitamins for secondary prevention of cardiovascular disease after acute myocardial infarction. Programs and Abstracts from the European Society of Cardiology Congress 2005; September 3-7, 2005. Stockholm, Sweden.

Translocation Essays

Translocation Essays Translocation Paper Translocation Paper Translocation A. The Munch pressure flow model The Principal of Pressure-Flow Model of Phloem Transport The Munch pressure-flow model is an explanation for the movement of organic materials in phloem . By the Munch pressure-flow experiment, two dialysis tubings are connected by a glass tube. The dialysis tubings only permeable to water or particles which have smaller size than the pores of the tubing,but impermeable to the larger solutes. As larger molecules such as proteins and polysaccharides(starch) that have dimensions significantly greater than the pore diameter of the dialysis tubing can pass through the tubings and they are retained inside the tubings. Smaller molecules such as water molecules and iodide ions are small enough to pass through the pores. The left-handed dialysis tubing contains 20%sucrose and iodine solution . The right-handed dialysis tubing contained 5% starch solution . The two entire dialysis tubings are submerged in distilled water of two separated beakers. Distilled water flows into the left-handed dialysis tubing because it has the higher solute concentration than that of the right-handed one. The entrance of water creates a positive pressure,thus a higher hydrostatic pressure is developed in left-handed tubing . The higher hydrostatic pressure in left-handed dialysis tubing induces water to flow from left to right through the glass tube. Therefore,water flows toward the right-handed dialysis tubing. This flow not only drives water toward the right tubing, but it also provides enough force for water to move out from the membrane of the right-handed dialysis tubing- even though the right-handed tubing contains a higher concentration of solute than the distilled water. Eventually the system will come to equilibrium. The left-handed dialysis tubing represents the sucrose regions, i. e. the photosynthetic tissues where sugars and other organic solutes are continuously synthesized. This results in a low water potential at the source so that large amount of water in xylem enters the cells here. The hydrostatic pressure of the sucrose increase. The right-handed dialysis tubing represents the sinks regions, sites of assimilation such as the actively growing parts or the sites for storage . Here solutes are being used up constantly , or converted to insoluble forms for storage . In other word , they are being unloaded from the sieve tubes . This leads to higher water potential at the sink and subsequently less water enters the cells by osmosis. The hydrostatic pressure of these cells is thus lower than those at the sucrose. A hydrostatic pressure gradient is therefore built up between the sucrose(left-handed tubing) and the sink(right-handed tubing) . This leads to the mass flow of liquid through the phloem (glass tube) from the sucrose to the sink, and water is forced back to the xylem by hydrostatic pressure. The pressure gradient is maintained due to the continuous production and consumption of solutes. In plants, sieve tubes are analogous to the glass tube that connects the two dialysis tubings. Sieve tubes are composed of sieve-tube members, each of which has a companion cell. It is possible that the companion cells assist the sieve-tube members in some way. The sieve-tube members align end to end, and strands of plasmodesmata (cytoplasm) extend through sieve plates from one sieve-tube member to the other. Sieve tubes, therefore, form a continuous pathway for organic nutrient transport throughout a plant. An area where the sucrose is made is called a source. At the Source (e. g. , leaves). During the growing season, photosynthesizing leaves are producing sugar. Therefore, they are a source of sugar. This sugar is actively transported into phloem. Again, transport is dependent on an electrochemical gradient established by a proton pump, a form of active transport. Sugar is carried across the membrane in conjunction with hydrogen ions , which are moving down their concentration gradient . After sugar enters sieve tubes, this increases the solute concentration of the sieve tubes,so water passes into them passively by osmosis. In the Stem. The buildup of water within sieve tubes creates the positive pressure that accounts for the flow of phloem contents. An area where sucrose is delivered from the sieve tube is called a sink. Sinks include the roots and other regions of the plant that are not photosynthetic , such as young leaves and fruits. Water flowing into the phloem forces the sugary substance in the phloem to flow down the plant. The addition of water from he xylem causes pressure to build up inside the phloem and pushes the sugar down. At the Sink . The roots (and other growth areas) are a sink for sugar, meaning that they are removing sugar and using it for cellular respiration. After sugar is actively transported out of sieve tubes, water exits phloem passively by osmosis and is taken up by xylem, which transports water to leaves, where it is used for photosynthesis. Now, phloem contents continue to flow from the leaves (source) to the roots (sink). The pressure-flow model of phloem transport can account for any direction of flow in sieve tubes if we consider that the direction of flow is always from source to sink. Translocation is a passive process that does not require the expenditure of energy by the plant. The mass flow of materials transported in the phloem occurs because of water pressure, which develops as a result of osmosis. Discussion 20% sucrose solution has a lower water potential than that of 5% starch solution, more water molecules move into the sucrose dialysis tubing than that of the starch dialysis tubing. The rise in solution level in sucrose dialysis tubing will be much more significant when compare to that of starch dialysis tubing. In the experiment , the water in the left hand beaker turn from colorless to yellowish brown, this indicated that there is a movement of iodide ions and water molecules across the selectively permeable dialysis tubing. As the experiment proceeds , there is a rise of brown solution in the glass tubing at the right hand tubing. The solution flows through the glass tube slowly. This suggests that there is a net movement of water molecules into the dialysis tubing since the water potential of the sucrose solution is higher than that of pure water. The water level in the right hand dialysis tubing decrease over the time as the experiment is carried on. This is due to the hydrostatic pressure applied by the left-hand flowing solution on the right-hand dialysis tubing. The flow rate of the solution is not constant throughout the experiment, the flow rate increases at first then it slows down and eventually reaches a static static flow rate. This is because an equilibrium status has reached. At first , the water potential of sucrose solution is higher than that of water, therefore water molecules move into the tubing. The continuos influx of water molecules into the left -hand tubing lead to the sucrose-iodine solution move along the glass tube, and the flow rate However,this has generated the hydrostatic pressure towards the right-hand tubing, pushing water molecules in the rich-hand dialysis tubing out of the tube. The net movement of water molecules from the right-hand tubing to the beaker made the starch solution more and more concentrated. Therefore the water potential of the starch solution is lower , water molecules may start to move back to the tubbing. This explains why the flow rate slow down and eventually maintain at a static rate. Due to the hydrostatic pressure, the sucrose solution will be transferred to the right hand tubing which the starch remain in the same tubing. mrothery. co. uk/plants/planttransportnotes. htm http://en. wikipedia. org/wiki/Pressure_Flow_Hypothesis http://en. wikipedia. org/wiki/Dialysis_tubing http://vinzchamakh. wordpress. com/category/biology/chapter-8-transport/