Here's a breakdown:

* Hemoglobin: This is the protein in red blood cells that carries oxygen throughout the body. It's made of two alpha globin chains and two beta globin chains.

* Mutation: In sickle cell disease, a specific mutation occurs in the gene responsible for making the beta-globin chain. This mutation causes a single amino acid change (glutamic acid to valine) in the beta-globin protein.

* Sickle-shaped red blood cells: This amino acid change alters the shape of the hemoglobin molecule, causing it to clump together and deform the red blood cells into a sickle shape.

* Consequences: These sickle-shaped red blood cells are rigid and sticky, leading to a range of complications including:

* Blockage of blood vessels: The sickle cells can clog blood vessels, leading to pain, organ damage, and stroke.

* Anemia: The sickle cells are destroyed faster than normal red blood cells, leading to anemia.

* Other health problems: Sickle cell disease can also lead to other health problems such as infections, delayed growth, and vision problems.

Important note: Sickle cell disease is an inherited condition. Both parents must carry the gene for sickle cell trait for their child to have sickle cell disease.