Explain why the sickle cell mutation is selected
Genetics – mutation part 2
Sickle cell disease (SCD) is a category of blood disorders that are usually passed down over the generations.  Sickle cell anemia is the most common form of anemia (SCA).  It causes a change in the oxygen-carrying protein haemoglobin, which is found in red blood cells.  Under some conditions, this results in a rigid, sickle-like shape.  Symptoms of sickle cell disease typically appear about the age of 5 or 6 months.  A variety of health issues, including pain attacks (“sickle cell crisis”), anemia, swelling in the hands and feet, bacterial infections, and stroke, can occur.  As people age, they can experience long-term pain.  In the developing world, the average life expectancy is 40 to 60 years.  Sickle cell disease is caused by an individual inheriting two defective copies of the haemoglobin gene (HBB), one from each parent.  This gene is found on chromosome 11 of the human genome.  Depending on the exact mutation in each haemoglobin gene, there are many subtypes. Temperature shifts, tension, dehydration, and high altitude can all cause an assault.  A individual with a single abnormal copy of the gene is said to have sickle cell trait if they do not have any symptoms.  These individuals are also recognized as carriers.  The disease is diagnosed by a blood test, and in certain nations, all newborns are tested for the disease at birth.  It’s even possible to get a diagnosis when pregnant. [number four]
Genetics – pleiotropy
“The ratio of sickle-cell trait carriers among newborns to those among reproducing adults can, in fact, provide a direct estimate of the typical homozygote’s fitness versus that of the heterozygote.”
Malaria is thought to have risen drastically as agriculture developed, causing forests to be cleared and people to congregate in villages. This happened around 2000 BC in West Africa, showing that the sickle cell allele has actually been near equilibrium for a long time.
How long would it take for the sickle-cell allele to drop from a frequency of 0.13 to a frequency of one in a thousand if malaria were eradicated? Assuming heterozygotes are as fit as non-sickle-cell individuals, how long would it take for the sickle-cell allele to drop from a frequency of 0.13 to a frequency of one in a thousand if malaria was eradicated?
First and foremost, keep in mind the assumptions!! There is only one genetic locus with constant fitnesses, no mutations, migration, or meiotic drive. In more complex models, Fisher’s fundamental theorem (as loosely interpreted) does not always hold.
A single-stranded RNA molecule with a sequence of three-base codons is depicted in this diagram. When converted into protein, each three-nucleotide codon refers to an amino acid. The corresponding amino acid of the protein is changed when one of these codons is changed by a point mutation.
A single nucleotide base is modified, added, or removed from a DNA or RNA sequence of an organism’s genome in a point mutation or substitution.
1st Point mutations have a number of implications on the downstream protein product, which are moderately predictable depending on the mutation’s specifics. In terms of protein production, structure, and function, these consequences can vary from no effect (e.g. synonymous mutations) to deleterious effects (e.g. frameshift mutations).
Point mutations are most commonly found during DNA replication. One double-stranded DNA molecule splits into two single strands, each of which serves as a template for the formation of the complementary strand. A single point mutation has the ability to modify the entire DNA sequence. The amino acid that the nucleotides code for can be modified by changing one purine or pyrimidine.
Gel electrophoresis to determine genotype
Sickle cell disease is most common among African Americans in the United States. One in every 12 African Americans and one in every 100 Hispanic Americans has the sickle cell gene, which means they are sickle cell disease carriers.
A mutation in the hemoglobin-Beta gene on chromosome 11 causes sickle cell disease. Hemoglobin is a protein that carries oxygen from the lungs to the rest of the body. Normal hemoglobin (hemoglobin-A) red blood cells are smooth and round, and they glide through blood vessels.
Hemoglobin S molecules, which are irregular in people with sickle cell disease, bind together and form long, rod-like structures. Red blood cells become rigid and sickle-shaped as a result of these structures. These red blood cells pile up due to their form, causing blockages and causing damage to vital organs and tissue.
Sickle cells can block blood flow into veins, causing lung tissue damage and symptoms such as acute chest syndrome, pain episodes, stroke, and priapism (painful, prolonged erection). The spleen, kidneys, and liver are also affected. Patients, particularly young children, are easily overwhelmed by bacterial infections due to spleen damage.