Aging and Immortality

Abstract

AGING AND IMMORTALITY BY DANIEL JIAO T he oldest verified person lived to 122 years old and died in 1997 but even today we have people claiming to be even older such as Mbah Gotho who states he is 145 years old. The current worldwide average expectancy is 71 years old but the variety of ages we live to is enormous. We still have much to learn about what leads to these differences in life spans leading us to question what aging is. Numerous studies have been done inves- tigating the various causes of aging such as telomerase, mitochondrial signaling, sensory signaling, diet, and microRNAs. Telomerase is an RNA dependent DNA polymerase which is used to lengthen the ends of chromosomes by adding base pairs. The ends of each of the arms of the chromosome are called telomeres and they protect the cell from losing important coding regions on chromosomes. Base pairs are lost from the chromosome ends upon each division which slowly shorten the telomere. This continues until a point at which the cell can no longer divide which is called cellular senescence. The cell is then able to kill itself by the apoptotic pathway when the critical length is met during cellular senescence. In the end all telomeres are controlled by the telomerase activity and erosion during cell division and it is one of the reason why organisms such as humans cannot live forever currently. The idea that the shortening of telomeres and apoptosis is important in regulation of tumor suppression is strongly supported Investigations into the telomeres of different organisms such as lobsters can provide greater insight into their role and functions in aging. Lobster are known to have indeterminate growth meaning that they continue to grow until they die. This is un- like humans which have determinate growth and stop growing mostly after puberty. We can then think about chromosomal shortening and why lobsters are able to replicate their cells continuously but humans are not. The answer is the lobster’s telomerase which is con- tinuously produced even after maturation of the tissues which is unlike human cells which mostly exhibit no telomerase activity after differentiation. Telomerase is only one of the many factors that plays a role in aging however so even though lobsters theoretically can keep dividing their cells continuously they usually live 30-50 years depending on gender. The fact that lobsters do not live forever or for unreasonable years shows that other factors play huge roles in determining life span such as mutations, diseases, and diet. Berkeley Scientific Journal | FALL 2016