Question

1.) A rare human disorder affecting telomere is known and called dyskeratosis congenita(DKC). Which of the following would you predict to be an observation in the detection of this disorder? a.) initial symptoms are found in rapidly dividing cells like skin. nails and bone marrow

b.) This disorder isn't initially lethal due to the actions of telomerase in early development

c.) Children and not adults are affected

d.) all of the choices are correct

3.) Which of the following best describe the problem associated with telomeres?

a.) eukaryotic chromsomes are linear thus leaving a gap remaining on the lagging strand where the RNA primer was located

b.) telomeres are rich in gene density and are replicated first

c.) telomeres are characteristic of circular prokaryotic chromosomes

d.) eukaryotic chromsomes are linear thus leaving a gap remaining on the leading strand where the RNA primer was located

Answer 1

• Dyskeratosis congenital (DKC) is a rare genetic disorder that occurs due to mutations in the genes that are involved in the maintenance and normal functioning of telomeres. Telomeres are structures that are present at the ends of chromosomes and help in protecting chromosomes from getting degraded or fusing together. The length of telomeres gets shorter with each cell division. Individuals suffering from DKC exhibit characteristic skin, nail, hair, and bone marrow problems, as the cells in these areas divide rapidly and are more susceptible to the consequences of telomere shortening. Therefore the option a)initial symptoms are found in rapidly dividing cells like skin. nails and bone marrow is an observation for the detection of this problem.
• The option a.) eukaryotic chromosomes are linear thus leaving a gap remaining on the lagging strand where the RNA primer was located best describes the problem associated with telomeres. This happens because as the replication fork positions itself at the end of the chromosome, which is linear in eukaryotes, The Okazaki fragments (on the lagging strands) are not able to cover a short region of the DNA at the end, and the DNA fragment can’t be initiated further by the DNA polymerase. Thus this short stretch of DNA at the chromosomal end stays uncopied and the primer of the last fragment is not substituted with DNA. This causes a gap on the lagging strand where the RNA primer was located.