From my classmate ( you can read )
Sickle Cell Anemia: How it’s formed and How it Harms
Sickle cell anemia is common mutation amongst the hemoglobin molecule that causes distorted, crescent-moon shaped (sickle-shaped) hemoglobin molecules that inhibit them from reaching their full functional potential. The cause of sickle cell anemia is directly linked to replication, the 6th topic we’ve discussed in class; the replication of the gene is mistakenly given a single wrong protein that causes the misfolding amongst the protein chains in the molecule, causing it to fold inward upon itself, leading to the sickle shape. This mistake is a random point-mutation that lies within the beta-peptide chain, it occurs in 1 in every 365 African Americans and 1 in every 16,000 Hispanics. The effects sickle cell anemia on the human body is quite extensive. The sickle cell’s lack of functionality to bind oxygen makes blood oxygen deprived as opposed to oxygen rich; by lacking oxygen, most major body systems as well as single organs and single nerve bundles will become oxygen deprived and start to decline in function and shut down. There’s also a severe risk for infections and episodes called sickle cell crises that are extremely painful and can last anywhere from a few days to a full week.
To begin with, one must delve deep into the red blood cell to shine focus on one specific molecule within the red blood cell: the hemoglobin molecule. The hemoglobin molecule is one of the most highly recognized molecules in the blood as it plays such a vital role in the human body. Hemoglobin is widely recognized for its extremely imperative job of transporting oxygen through the blood stream, essentially keeping the blood oxygenated as well as delivering oxygen to other parts of the body **details on its delivery of oxygen**. A single hemoglobin molecule is globular in shape, and is composed of four protein subunits. It holds the capacity to bind up to four oxygen molecules for transport by undergoing a transformational change **insert background on conformational change**.
The process of assembling a hemoglobin molecule is like any other DNA replication-DNA is transcribed to form an RNA template strand, undergoes RNA processing to form mRNA, mRNA is translated into a protein chain. So how and where do things go wrong in this replication process? Under careful study by Nobel Prize winner Linus Pauling, it was discovered that sickle cell anemia contains a random mutation within its DNA genome. This random mutation is then transcribed into mRNA and carried into translation to give rise to the incorrect protein, ultimately damaging the entire protein sequence by one single swap of proteins. In a normal hemoglobin DNA sequence, there is the regular, ideal G-A-G sequence that gets base paired to C-T-C to form the DNA helix; in the atypical Hemoglobin S DNA Sequence, there is the mutated DNA helix with the G-T-G sequence that gets base paired to C-A-C. The subtle swap of the adenine nucleotide in the normal DNA sequence for the thymine nucleotide in atypical DNA sequence instills catastrophic consequences throughout the human body.
Before discussing the negative ramifications the hemoglobin S molecule has on the body, it’s important to continue discussing the formation of its proteins and protein chains. The normal hemoglobin sequence produces an RNA strand with a template that reads G-A-G (the base pairings to the DNA sequence strand C-T-C), whereas the atypical hemoglobin sequence produces an RNA strand with a template strand that reads G-U-G (the base pairings to the DNA sequence C-A-C). It’s known that amino acids are assembled from the mRNA strand, with every 3 nucleotides forming a single amino acid product. For the normal hemoglobin molecule, the G-A-G nucleotides code for the assembly of glutamine; in the atypical hemoglobin, the G-U-G nucleotides code for the assembly of valine. This causes a distortion in the formed beta-peptide chain