Ans.
HD (Huntington's disease) is a genetic neurological disorder that occurs due to damage and death of brain cells. it is caused by an autosomal dominant mutation in HTT (huntingtin) gene, having a trinucleotide repeat section that makes HTT protein.
The mutation leads to an increase in this nucleotide repeat count, associated with formation of altered or mutated huntingtin protein. These altered proteins show deleterious affect on brain cells and result in Huntington's disease.
Thus, the correct answer is 'option A). a mutated gene.'
The human skin is the protective layer of the human body against the external forces like the temperature, sharp objects, microbes, fungi and other related materials that can penetrate and weaken the body however, the integumentary system prevents any harm come to the organism. The dermis is the skin area which has different structures that perform different functions.
Dendrites is 1
Soma is 2
Nylon sheeth is 3
Node of Ranvier is 4
Synapse is 5
D - an increase in tree cover in the tundra.
