Panspermia Handout and Activity!

Sickle Cell Disease Essay

Regina Gonzalez Toledo                                                                             September 17th, 2010.

Sickle Cells Disease                                                                       http://reginagt.blogspot.com/

SICKLE CELL DISEASE

Sickle cell disease is an inherited blood disorder characterized by defective hemoglobin, the molecule that transports oxygen in the blood. It gets it name from the shape of the red blood cells under low oxygen conditions. Some red blood cells become “sickle shape”, almost like a quarter moon shape and these get stuck in small blood vessels, and some parts of the body don’t get the oxygen needed to function properly. The disease is caused by a single letter change in the DNA. This change alters one of the amino acids in haemoglobin protein. The oxygen becomes low in the body and this brings later an attack.[i] By reading this essay, I hope you get a better understanding of this disease as well as its problems and consequences.

Genetics, biochemistry, cytology, mathematics, and chemistry just to name some, are the biology branches and sciences dedicated to study more and treat the sickle cell disease. A disease that is taking the life of hundredths of people every year.  

While having this disease most of the levels of organization of matter are affected; this is because this disease affects the blood, which is needed in all body functions, so our cells are damaged, as well as, our macromolecules, tissues, organs, organ systems, our whole organism and the rest of the population when it is transmitted from generation to generation.

Due to the problem that this disease cause to the body, our macromolecules are strongly involved, especially our biological macromolecules which are composed by carbon, hydrogen and oxygen. This macromolecules are also known as sugars and their main functions are: source of energy and to provide structural support.

Haemoglobin, the molecule that is affected in this disease, is the iron-containing protein attached to red blood cells that transports oxygen from the lungs to the rest of the body. Haemoglobin bonds with oxygen in the lungs, exchanges it for carbon dioxide, and then transports the carbon dioxide back to the lungs to be exhaled. Hemoglobin has characteristics of both the tertiary and quaternary structures of proteins. Most of the amino acids in hemoglobin form alpha helices, connected by short non-helical segments. In most humans, the hemoglobin molecule is an assembly of four globular protein subunits. Each subunit is composed of a protein chain tightly associated with a non-protein heme group.

A mutation or error in this gene is what causes sickle cell disease. This mutation is thought to have originated in areas of the world where malaria was common, since people with sickle trait do not get malaria. The sickle trait actually protects them from the parasite that causes malaria, which is carried by mosquitoes. Malaria is most often seen in Africa and in the Mediterranean area of Europe. Children who inherit the genetic mutation from both parents will have sickle cell disease. Children who inherit the mutation from only one parent will not have the disease, but will carry the trait for it and can pass it on to their children. The mutation affects the normal development of the protein that carries oxygen in red blood cells, called haemoglobin.  What happens in the sickle cell disease is a missense mutation. With a missense mutation, the new nucleotide alters the codon so as to produce an altered amino acid in the protein product. The replacement of A by T at the 17th nucleotide of the gene for the beta chain of hemoglobin changes the codon GAG (for glutamic acid) to GTG (which encodes valine). Thus the 6th amino acid in the chain becomes valine instead of glutamic acid, as shown in this chart:[ii]

This disease, brings within many problems, as I mention before mostly all the levels of organization of living matter are affected, this means that all major organs are affected too by sickle cell disease. The liver, heart, kidneys, gallstone, eyes, bones, and joints can suffer damage from the abnormal function of the sickle cells and their inability to flow through the small blood vessels correctly. Some of the problems can be:

·         increased infections

·         leg ulcers

·         bone damage

·         early gallstones

·         kidney damage and loss of body water in the urine

·         eye damage.[iii]

We can't prevent sickle cell anemia because it's an inherited disease. However, people can take steps to reduce its complications. People who are at high risk for sickle cell anemia and are planning to have children may want to consider genetic counseling. A counselor can help them understand the risk of having a child who has the disease and help explain the choices that are available for the couple. [iv]

With all of this, we can now know that Sickle Cell Anemia is a serious disease in which the body makes sickle-shaped red blood cells. This cells don't move easily through your blood vessels. They're stiff and sticky and tend to form clumps and get stuck in the blood vessels. Early diagnosis of sickle cell anemia is very important, people who have the disease need prompt and proper treatment. There is no available cure; however, there are treatments for the symptoms and complications of the disease. Some treatments may include medicines, fluids, or even bone marrow transplants may offer a cure in a small number of cases.

With good health care, many people who have sickle cell anemia can live productive lives. They also can have reasonably good health much of the time and live longer today than in the past. If someone have sickle cell anemia, it's important to adopt or maintain a healthy lifestyle, take steps to prevent and control complications.

 

Refences:

---

[i] Sickle Cell Disease Association of America. http://www.sicklecelldisease.org/about_scd/index.phtml Last updated: unknown, last accessed: 16/09/10.

[ii] Mutations. http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/M/Mutations.html Last updated: September 2, 2010, last accessed: 16/09/10.

[iii] University of Maryland, Medical Center; Blood Diseases.  http://www.umm.edu/blood/sickle.htm Last updated: January, 30, 2008, lat accessed: 16/09/10.

[iv] US Department of Health and Human Services http://www.nhlbi.nih.gov/health/dci/Diseases/Sca/SCA_LivingWith.html Last updated: unknown, last accessed: 16/09/10.