Account for the differences in oxygen consumption observed between:
Note added March Below is the article I wrote 6 years ago, but the evidence has changed in the interim, and my thinking has become more nuanced. My thinking was based on theory and epidemiology. Replicative senescence based on rationing telomerase is one of the oldest modes of programmed death in protozoans, long before there was multi-celled life.
It is natural to imagine that it is a conserved evolutionary pathway of programmed aging in humans. People with shorter telomeres have shorter life expectancies and higher mortality risk than people the same age with longer telomeres. Since that time, there is new epidemiology and new biochemistry.
The epidemiology, much to my surprise, has linked longer telomeres with some cancers—notably melanoma and lung cancer. New biochemistry has linked telomerase to the Horvath Aging Clock in the wrong direction. Telomerase accelerates aging, according to observed methylation patterns.
I still believe that longer telomeres are a net benefit, potentially adding 3 to 5 years to our lives.
Longer telomeres are a major protection against cardiovascular disease. I no longer believe that telomeres are the primary aging clock, or that major gains in life expectancy can be achieved through telomere extension. Telomere biology has the potential to extend human life span, to dramatically lower rates of the great remaining killer diseases: The private sector is doing a little better — there are several companies selling herbs that stimulate our own bodies to liberate telomerase.
But this is short-sighted venture capital, and what we need is focused research with a ten-year vision. The body knows perfectly well how to lengthen telomeres, but chooses not to.
All we have to do is to signal the body to activate the telomerase genes that are already present in every cell. Three objections raised against telomerase research 1.
But living systems are open, taking in free energy in the form of food or sunlight, dumping their entropy out into the environment. There is no reason that such systems cannot maintain themselves indefinitely. Indeed, growth and maturation would not be possible if this law of physics applied to open thermodynamic systems.
Since the 19th Century when the laws of thermodynamics were formulated, it has been understood that aging cannot be explained from physics, and therefore commands an explanation from evolution. It is unlikely that any simple adjustment to physiology that humans can discover will do better than evolution has done over millions of years.
Aging is a form of programmed death, on a flexible but finite schedule. It is fixed in our genes. Telomere attrition has been used to time the life cycle and form a basis for programmed death for at least a billion years.
This mechanism is the precursor to telomeric aging that exists to the present day in humans and many other higher animals.- Compare and Contrast Mitosis and Meiosis Meiosis and mitosis describes the process by which cells divide, either by asexual or sexual reproduction to produce a new organism.
Meiosis is a form of cell division that produces gametes in humans these are egg cells and sperms, each with reduced or halved number of chromosomes. An essay describing the processes that make up mitosis (cell replication).
Very good. The process of MitosisMitosis is the term used to describe cell division for replication. The product at the end of mitosis is two daughter cells both genetically identical to the original (parent) cell.3/5(1). Mitosis is the process by which a eukaryotic cell separates the chromosomes in its cell nucleus into two identical sets, in two separate nuclei.
It is a form of karyokinesis, or nuclear division. It is a form of karyokinesis, or nuclear division. Review of DNA Polymerase. So far in our discussions about DNA replication, we've talked about a handful of enzymes that help us by changing and moving parts of .
Cell Structure, Division and Transport. Animal and plant cells have many features in common, such as a nucleus, cytoplasm and cell membrane. Plant cells have a cell wall made of cellulose, a large vacuole containing cell .
During the replication process, two centrosomes move to opposite sides of a cell, with microtubules form a path for the motor proteins of chromosomes to follow as they pull and separate towards the newly formed cells and this occurs in both mitosis and meiosis.