The correct answer is an accumulation of microorganisms in deep marine environments.
Chalk rock refers to a pure form of limestone produced in tropical and warm seas about 100 million years ago in the Cretaceous period. The microscopic marine algae known as coccoliths thrived in the ancient seas. Their shells were comprised of calcite. With the death of the algae, their bodies sunk to the floor of the sea and sediment of chalk got deposited.
Over many years layers of chalk sediment got deposited and resulted in compaction of loose sediment into solid chalk rock.
DNA ligase is the enzyme that repair irregularities and breaks in the back bone of double stranded DNA. The enzyme function by sealing the repair in the DNA, it seals recombination fragments and it connects okazaki fragments during replication of DNA.
If a mutation reduce the amount of ligase, all the functions of the ligase enzyme listed above will be affected negatively.
Established on the data, sickle cell hemoglobin displays altered primary structure and altered quaternary structure; the secondary and tertiary structures may or may not be altered. The sickle cell disease is a cluster of disorders that disturbs hemoglobin, the molecule in red blood cells that transports oxygen to cells all over the body. A person with this disorder have uncharacteristic hemoglobin molecules named hemoglobin S which can interfere with red blood cells into a sickle or crescent shape.
