THE MOLECULAR BASIS OF INHERITANCE
DNA MAKES RNA MAKES PROTEIN
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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extra DNA at the ends of chromosomes that code for proteins
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DNA that gets longer with every round of replication
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Repeating segments of DNA that get shorter with every round of replication
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DNA sequences that are cut out by the spliceosome
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Detailed explanation-1: -A telomere is a region of repetitive DNA sequences at the end of a chromosome. Telomeres protect the ends of chromosomes from becoming frayed or tangled. Each time a cell divides, the telomeres become slightly shorter. Eventually, they become so short that the cell can no longer divide successfully, and the cell dies.
Detailed explanation-2: -At each cell division, the telomeres shorten because of the incomplete replication of the linear DNA molecules by the conventional DNA polymerases. This is called the end replication problem [6]. This is specifically due to the resection and fill-in reaction during the synthesis of the telomere leading-strand [7, 8].
Detailed explanation-3: -Telomeres are the physical ends of eukaryotic chromosomes. They protect chromosome ends from DNA degradation, recombination, and DNA end fusions, and they are important for nuclear architecture. Telomeres provide a mechanism for their replication by semiconservative DNA replication and length maintenance by telomerase.
Detailed explanation-4: -In human cell lines, telomeres generally shorten by 30–200 base pairs at each round of DNA replication, but only approximately 10 base pairs of this reduction are a consequence of the end-replication problem; the remaining loss is likely owing to oxidative damage (Monaghan and Haussmann, 2006).
Detailed explanation-5: -Every time a cell divides, each chromosome needs to be duplicated to provide a copy of genetic information for the new cell. However, the very end of each chromosome cannot be copied. Therefore, every time a chromosome is duplicated the telomeres become shorter.