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ADAM'S CURSE, IS IT WITH US TODAY?

ADAM’S CURSE, IS IT WITH US TODAY?
Biblical tradition tells the story of creation with man as the 1st sex, and woman the second, created from Adam’s rib.
Biology conveys a different tale for the evolution of sexes, however revealing that man, is the second sex not woman. Recent research evidences suggesting that man not only be the 2nd to arise, but the 1st to disappear.
‘Y’ in trouble
The human Y has lost 1393 of its 1438 original genes over the course of its existence. Researchers have found that, Y is degrading fast; losing genes at rate of 5 per million years and the Y will ‘self destruct’ within the next 10 million years.
Back 300 million years ago, we had no sex chromosomes, only ordinary autosomes.Then suddenly a chance mutation occurred in the ancestral Y, mutating the SOX3 to the SRY gene. The ancestral X retained the unmutated SOX3.And then sex chromosome emerged.
Between 80-300 million years ago, inversion took place in Y and the ultimate result is only 2 distal ends of X and Y remains identical known as pseudoautosomal regions. Men are basically genetically modified women. For males there is curse of the lone X.they have ended up with an array of inherited condition and diseases related to problem on the X chromosome.
What are the reasons for greater mutation in ‘Y’?
The Y chromosome is unique in human genome. It is pathetic little chromosome, gene poor, (few genes interspersed with lots of junk) prone to deletions and loss.
Human Y chromosome is passed exclusively through sperm, which undergo multiple cell division during gametogenesis each cell division provides opportunity for mutation, and sperms are stored in the highly oxidative environment of the testes which encourages further mutation. These are the reasons; put the Y at a risk of mutation greater than the rest of the genomes.
Will we have males?
Scientists have long been suspected that, y is deteriorating and could disappear entirely within the next 10 million years.
Will this be the end of evolution for humans?-if this happens it won’t be the end of males.instead, another gene takes over and new sex genes start evolving.
Will there be new sex chromosome evolution in humans?
May be it will happen in different ways in different population, and we will split in to 2 species.
But what happens if X takes another evolutionary direction and become asexual?
Unisex reproduction by females is one of the options for the survival of humanity .(Female eggs fertilized by nuclear X chromosome of another female and implanted by IVF method.Eventhough several vital genes must come from males for survival, certain Rodent species –male vole of Europe and country rat of Japan are living healthy ,have no Y and no SRY genes.
Hope for Y’s future:
Y chromosome palindromes- y has been secretly creating backup copies of its most important genes. These are stored in the DNA as mirror images or palindromes(which read the same forward and backwards)That means ,many of the genes on ‘Y’do occur as pairs-allowing the genes to repair themselves when they get damaged. Resent comparisons of the human and chimpanzee Y chromosomes show that the human y has not lost any genes since the divergence of humans and chimpanzees between 6-7 million years ago.
Conclusion
It has been predicted that ‘Y’ will continue to decay and lose genes. Before the ‘Y’has a chance to disappear completely, however humans will have already left the earth or perhaps they will have been brought to judgement day by the same god who created Adam in the 1st place.

PHYSIOLOGY TUTORIAL

Human aging can be stopped by adding telomerase: comment
We may think that, human aging can be stopped by adding telomerase but, telomerase causes cells to divide rapidly and uncontrollably. Such an excessive cellular proliferation may leads to cancerous growth. So you can’t expect telomerase to become the elixir of your youth.
At the ends of each chromosome is a non functional strand of DNA called telomere. It has been observed experimentally that telomeres shorten with each successive cell division. Shortened telomeres activate a mechanism that prevents further cell multiplication. When telomeres become too short, the cells die.
In 1965, Leonard Hay flick discovered the Hay flick limit-phenomenon-is a number of times a normal cell divide before the telomere reaches critical length.
Somatic cells can only divide around 30-50 times due to Hay flick effect. On the other hand germcells, stemcells and cancerous cells (considered immortal –in the sense that they can reproduce indefinitely) contain telomerase that prevents Hay flick limit. This enzyme extends the telomere of chromosome and prevents shortening of telomere.

PHYSIOLOGY TUTORIAL

PHYSIOLOGY-REASONING OUT
Hormones responsible for growth are sexually dimorphic
Yes, the statement is correct.
Sexual dimorphism means difference in forms between males and females of the same species. In animals that have separate sexes, males and females will always different, but in highly dimorphic species,2 sexes look very different and are often quite unequal in size.
Sex differences in the pattern of circulating somatotropin (ST) and circulating concentration of IGF (insulin like growth factor) and IGF-binding protein were demonstrated in rapidly growing prepupertal animals.The differences are consistent with the hypothesis that the somatotropic axis is a mechanism mediating sex differences in growth.Differences in circulating pattern of these hormones may arise from the actions of steroids during sexual differentiation and before puberty.
Several hypothalamic nuclei are sexually dimorphic i.e. there are clear difference in both structure and function between males and females. Some differences are apparent even in gross neuroanatomy.most notable is the sexually dimorphic nuclei within the preoptic area which is larger in males.(greater cell number and larger cell size in males).However most of the differences are subtle changes in the connectivity and chemical sensitivity of particular sets of hormones. The importance of these changes can be recognised by functional difference between males and females. For example secretion of GH is sexually dimorphic and this is one reason why in many species, adult males are much larger than females. and estrogens sensitive neuron in hypothalamus is sexually dimorphic.

PHYSIOLOGY TUTORIAL

PHYSIOLOGY SECRETS
Blood flow through the Reconditioning organs should be supplied constantly and adequately: comment
Ans-No.not necessary. Reconditioning organs like G.I.T, skin and kidney can tolerate significant reductions in blood flow for a considerable length of time. Because they receive blood flow in excess of their own needs. They can withstand temporary reductions in blood flow much better than other organs (heart and skeletal muscle) that do not have this extra margin of blood supply, brain in particular suffer irreparable damage when transiently deprived of blood supply. During exercise some of the blood that normally flows through G.I.T, kidney is diverted instead to skeletal muscle. Likewise blood flow through skin is markedly decreased during exposure to cold to conserve heat.

Physiology secrets

PHYSIOLOGY SECRETS
Beyond Mendel’s law (variation in Mendelian genetics)
There are 2 common variations.
1. Blood types-Mendel studied, each character is determined by a gene with 2 alleles, i.e 2 alternate forms. But in blood types ,unlike the genes Mendel studied, which had only 2 alleles, the blood type gene I exists in 3 distinct forms. The 3 alleles are IA, IB, IO.The A and B alleles are co-dominant, and both are completely dominant to O.However, even though 3 possible alleles in human, an individual can have only 2 of the alleles in his or her genes. And 4 possible blood types exist.
2.Maternal inheritance and Mitochondrial genes- The basis of the law of segregation is that both parents contribute genes equally to offspring. But in the case of mitochondria, it is interesting to note that the genes in the mitochondria are inherited only from mother. Why not from father? Because mitochondria are located in the middle of the sperm not in the head region that enter the egg. In rare instances, when mitochondria from sperm enter an oocyte they are destroyed selectively early in embryonic development.

physiology secrets

PHYSIOLOGY SECRETS
Reasoning out: Single gene traits obey All or None Law-comment
Yes. Single gene traits are discrete or qualitative and providing All or None phenotype (normal vs. affected) instead multiple genes that regulate height, skin colour-result in continuously varying phenotype. (Skin colour is controlled by 8 genes)Both single gene and polygenic traits can also be multifactorial i.e. they are influenced by environement.pure polygenic not influenced by environment are rare. (Eye colour-polygenic not environmental)