Dr. Moalem discusses on p. 74 - 77 about the genetic mutation labeled favism by scientists and how favism can have a potentially deadly effect on the body by resulting in destruction of red blood cells. This genetic mutation relates to Big Idea 4 (Biological systems interact, and these interactions possess complex properties) in that favism disrupts the interactions of the red blood cells and their transfer of O2 and CO2 to various organs by bursting the red blood cells, potentially leading to death.
Using the book Survival of the Sickest and the internet with credible sources, define favism and explain how favism causes anemia at the molecular level. Also, describe the function of G6PD protein in relation to favism, then describe the process of G6PD protein production starting from its location in the chromosome, then transcription and translation of DNA, and then its protein modification before being used for its purpose. Include process locations, enzymes, and specific molecules involved in the process.
Paul Sone (jsone4@students.d125.org)
Favism is a condition derived from fava beans, which have historically been known to be “fave dei morti- ‘beans of the dead.’” (73, Survival of the Sickest) Favism is “an inherited enzyme deficiency carried by 400 million people,” making it the most common enzyme deficiency in the world. In its most severe forms, those who have favism and eat fava beans “experience rapid, severe anemia that can often lead to death.” (73, Survival of the Sickest)
ReplyDeleteFava beans contain two sugar related compounds: vicine and convicine. Both of these compounds produce what are known as free radicals, “especially hydrogen peroxide.” (75, Survival of the Sickest) G6PD, or “glucose-6-phosphate dehydrogenase is a cytosolic enzyme…whose main function is to produce NADPH, a key electron donor in the defense against oxidizing agents,” such as the hydrogen peroxide in fava beans. (http://www.genecards.org/cgibin/carddisp.pl?gene=G6PD) G6PD is an enzyme in the pentose phosphate pathway. G6PD converts glucose-6-phosphate into 6-phosphoglucono-δ-lactone and is the rate-limiting enzyme of this metabolic pathway that supplies reducing energy to cells by maintaining the level of the co-enzyme NADPH. The NADPH maintains the supply of reduced glutathione in the cells that is used to gather free radicals that cause oxidative damage, such as the hydrogen peroxide buildup caused by eating fava beans. The G6PD and NADPH pathway is the only source of reduced glutathione in red blood cells. The role of red cells as oxygen carriers puts them at substantial risk of damage from oxidizing free radicals. Fava beans, contain high levels of vicine, divicine, convicine and isouramil, all of which are oxidants that cause oxidative stress if a person has a G6PD deficiency. When all remaining reduced glutathione is consumed, enzymes and other proteins (including hemoglobin) are subsequently damaged by the oxidants, leading to electrolyte imbalance, cross-bonding and protein deposition in the red cell membranes. Damaged red blood cells are phagocytosed and sequestered (taken out of circulation) in the spleen. This relates to the immune system because macrophages, or phagocytic cells that are “Big Eaters,” dispose of damaged red blood cells.
G6PD is an enzyme “The gene that gives instructions on how G6PD is made is found in the X chromosome only, thus G6PD deficiency is described as X-linked.” (http://nursingcrib.com/nursing-notes-reviewer/g6pd-deficiency/) A lack of the enzyme G6PD means that red blood cells can be damaged and destroyed when the person is exposed to some chemicals (including some medicines) or during some infections. G6PD is made in red blood cells. DNA is transcribed to mRNA, mRNA is transferred out of the nucleus to free ribosome's by messenger proteins, ribosomes are organelles made of 2/3 rRNA and 1/3 protein, ribosomes bring the tRNA molecules to the mRNA, tRNA reads the codons on the mRNA and brings about the appropriate amino acid. That amino acid is attached to a growing chain of amino acids via enzyme catalysed reactions. Once the polypeptide chain is complete it is transferred to the endo-membrane system where the protein is manipulated, such as additions of carbohydrates to glycoproteins as well as change the proteins shape or its tertiary structure, or the protein can be transported to the golgi apparatus where further alterations to proteins occur finally the protein is ready and exported from the golgi apparatus to the final designation. Since enzymes are proteins they are made the exact same way and this is the same.
If the hydrogen peroxide in fava beans “isn’t cleared out with the help of G6PD, it starts to attack your red blood cells…when that happens, the rest of the cell leaks out, resulting in hemolytic anemia.” (75, Survival of the Sickest) “Hemolytic anemia is a condition in which red blood cells are destroyed and removed from the bloodstream before their normal lifespan is over.” (http://www.nhlbi.nih.gov/health/health-topics/topics/ha/) Red blood cells carry oxygen to your body. They also remove carbon dioxide (a waste product) from your body. In hemolytic anemia, the bone marrow can't make red blood cells fast enough to meet the body's needs, which can ultimately lead to many health problems, such as fatigue, pain, irregular heartbeats called arrhythmias, an enlarged heart, and heart failure.
ReplyDelete(Taylor Young, tyoung3@students.d125.org)