Sickle cell anemia Essay Example | Topics and Well Written Essays - 1250 words

Sickle cell anemia - Essay Example value to carrying a single sickle-cell gene in these areas because people with only two alleles of the gene are much less likely to fall victim to malaria (Kwiatkowski, 2005). The condition is characterized by the shape of the individual’s red blood cells, which tend to adopt a rigid, abnormal ‘sickle’ shape to them that decreases the cell’s flexibility and can create a number of complications throughout the body as a result. This occurs as a result of a mutation in the hemoglobin gene and it affects approximately 1 in 5,000 Americans, most of who are of African American descent. The life expectancy for people with sickle cell anemia is shorter than normal averaging 42 for men and 48 for women (Platt, Brambilla & Rosse, 1994). The purpose of the present research is to identify the genetic origins of this illness and the affects it can have upon the body. There are a number of different forms of the disease which are classified based upon the mutations present within the blood. Sickle cell anemia is the term used to specifically apply to those individuals who present homozygosity for the mutation (Green et al, 1993). In these individuals, long-chain polymers of HbS have the effect of changing the normally smooth, donut-like shape of the red blood cells to a more spiked and rigid shape that makes the cell more susceptible to breakage. People who are heterozygous for the illness are generally carriers, having only one sickle gene and one normal gene that generally makes up for the deficits of the sickle gene. However, when the ‘normal’ gene is also abnormal in some way, other forms of the illness can manifest, typically referred to as compound heterozygous (Green et al, 1993). The sickling effect is caused by a point mutation in which the glutamic acid, a type of amino acid, is replaced with valine, a hydrophobic amino aci d, at the sixth position. When in low oxygen conditions such as being at a high altitude, this causes an aggregation of

Goldilocks Zone Properties Research Paper Example | Topics and Well Written Essays - 1250 words

Goldilocks Zone Properties - Research Paper Example According to a NASA journal titled â€Å"The Goldilocks Zone†, the Goldilocks Zone is very big. The journal also talks about researchers who are trying to extend the regions of the Zone by looking for signs of life in distant planets. Research shows that there are certain organisms that prefer acidic conditions and some that swim in hot boiling water. The journal goes on to talk about ecosystems that have been discovered where the sun never reaches, and there is very hot water enough to melt metal. This means that the Goldilocks zone is very big, and covers areas that might be considered uninhabitable. The aim of this paper is to give a detailed account of the properties of the Goldilocks Zone. One of the Goldilocks zone properties is the presence of liquid water on the surface of the planets (Brian, 2011). The only planet known to contain large water bodies on its surface is the earth and this is where water exists in its liquid form rather than ice (Davies, pp 129-150). Ocea ns, lakes and rivers are surface water bodies which sustain lives of animals that live in water and also humans on earth. Water in the Goldilocks zone should not be too hot to evaporate or too cold to freeze, therefore, in case water evaporates or freezes, all life will vanish. Since earth is at the centre of the Zone, it has a constant water surface whereby the water does not become too hot or too cold to sustain life. Mars is considered to be on the cold side of the zone while Venus is on the hot side hence these two planets are not habitable since their water surface is irregular. Water is able to sustain life by: Transporting materials around the human and animal body and it can resist frequent changes in temperature therefore offering a favorable environment for aquatic animals. Planets with a hydrogen atmosphere such as earth can maintain water flowing no matter the distance from the sun. Once water freezes or boils and lost into space, all earthly life will be lost. Liquid wa ter is a vital property for a region to be classified under the Goldilocks Zone (Brian, 2011). Position to a star determines whether or not a planet has liquid water (Brian, 2011). According to Brian, a star’s energy output, gravitational pull, and size determine the location of the Goldilocks Zone. Compared to other liquids, water has unique properties which make it essential for life (Davies, pp85-103). Oceans and lakes do not freeze rock solid because water expands when it freezes. According to Davies, ice floats on liquid water, and aquatic animals are able to live on the water below. Water can dissolve many substances and it takes a lot of energy to change its temperature. This means that when a region experiences hot temperature, water remains moderately cool, hence sustaining life. Therefore, presence of water in the Goldilocks zone is a fundamental property, since it is able to sustain life during the cold and hot conditions (Davies, pp85-103). As earlier mentioned, E arth falls under the Goldilocks Zone, and the presence of water on Earth gives it its relatively moderate type of weather. Temperature is another property of the Goldilocks Zone and is chiefly affected by climate as the Earth rotates. The orbit of the Earth is circular so when it orbits around the zone, it enables the temperatures to remain steady. This is contrary to planets such as Venus which has an