We are at a unique confluence of science and publishing in which the results of the former are being dispersed by the latter at such a rate that even the most ardent reader of popular science books can hardly keep up. This is good news for science, of course; its products are outstripping even Moore's law of doubling every 18 months, so updates and revisions are called for just as frequently. Luckily for publishers, readers are willing and able to plunk down a quarter of a hundred bucks to discover the secrets of life and the cosmos. Literary agents specializing in science tomes are demanding—and getting—five- and six-figure advances for their clients, and by most counts publishers are earning back those advances in a matter of months.

British science writer Matt Ridley is a participant in and beneficiary of this pleasant conjuncture, and he has rewarded his readers admirably with such biobestsellers as The Red Queen: Sex and the Evolution of Human Nature and The Origins of Virtue: Human Instincts and the Evolution of Cooperation—the latter being, in my opinion, the most readable book to date on evolutionary ethics. In Genome Ridley continues his expansion into larger themes, as he takes us on a roller-coaster ride through the very foundation of life: DNA. The carnival-ride metaphor is apt, because in Genome Ridley hits many highs and lows (depending on the complexity of the subject and his knowledge of it) and leaves the reader feeling a little dizzy at the end. The fault, on one level, is not Ridley's, as he has taken on a subject vastly deeper and more complicated than can possibly be covered in a single volume—any one of the 23 chapters could have been a book in itself. And he has succeeded in providing a highly readable and informative encapsulation of the science that promises to do for the 21st century what nuclear physics did for the 20th. A revolution is in the making, and Ridley has his finger on its pulse.
Ridley's technique is at once clever and delimiting: Each chapter represents a chromosome, for which he has chosen a single entity supposedly determined or influenced by that chromosome. For example, there are chapters on intelligence, instinct, self-interest, disease and stress—entities that he associates with chromosomes 6 through 10, respectively. It is a facile literary device to help readers get their minds around this illimitable subject, but I fear that it gives the wrong impression—Ridley's disclaimers notwithstanding—that such things as intelligence, instinct or self-interest are wholly located on a single chromosome and are therefore genetically programmed and biologically determined.
I sometimes wonder, only half in jest, if there isn't a metagene gene—a gene that causes people to think that everything is in our genes. Evolutionary psychologists could have a field day with the concept. Of course, Paleolithic cavepersons knew nothing about genes, so we must postulate that they tended to view the actions of others as either largely capricious or largely determined. Those who took the latter view would be those with the metagene gene, and they would of course be better adapted and more successful, because awareness of living in a deterministic world allows one to better determine cause-and-effect relationships, and that is what leads to enhanced survival and the propagation of one's genes, including the metagene gene.
Okay, I'm being rather facetious. I do think evolutionary psychology has much value to add to the social sciences. But the glut of books by authors who seem themselves to believe there is a metagene gene is, I fear, doing more harm than good to the public understanding of how science and nature really work.
Fortunately, in most cases Ridley does an admirable job of clarifying the enormous complexities involved in gene-environment interactions, demonstrating in numerous cases that it is next to impossible to say that any complex human trait (such as intelligence or athletic ability) is, say, 60 percent genetically determined and 40 percent environmentally shaped.
For example, in "Chromosome 11: Personality" Ridley discusses the gene D4DR, which is located on the short arm of the 11th chromosome and codes for dopamine, a neurotransmitter that stimulates the organism to be active—or not, if a shortage exists: A complete lack of dopamine, for example, causes humans (or rats) to become catatonic, and high levels of it make them frenetic. Ridley here summarizes the fascinating work of Dean Hamer, who in his quest to find genes for smoking and homosexuality discovered the gene (or, more precisely, the gene complex) for the novelty-seeking personality. It turns out that the D4DR gene sequence is repeated on chromosome 11; most of us have 4 to 7 copies, but some have only 2 or 3 and others have 8 to 11. Those with more copies of D4DR have a lower responsiveness to dopamine in certain parts of the brain. Hamer theorized that this might mean that they would need to
No they do not. Scientists study it to figure it out why some have it and others do not. It is quite rare, actually. Certain humans are capable of things most would consider strange and not human, such as being able to calculate things at an incredible speed, or an athlete faster than an Olympic medalist.
Yes they can. An AB parent can indeed sometimes have an O child. But it is by no means common. In fact it would be fair to say that it is exceedingly rare.
The one exception is in certain Asian groups. Some of these folks have a rare version of the ABO blood type gene called cis-AB. People with this gene version have an AB blood type but can easily have an O child.
<span>The energy which we are using in today's world for our needs is fossil fuel, we used to power our home by burning coal and run our vehicle through the oil or fossil fuel, but we should know that it is limited in quantity and cannot use it once it releases energy or burned, it is created by the dead organic materials like trees and animals etc. which slowly buried in the ground as the time goes and after 1000's of years it get pressurised and rise in temperature make that organic material into fossil fuel, so that's how the fossil fuel comes in existence, which we extract from the ground by drilling deep into the ground.</span>
The electrons stripped from glucose first end up forming oxygen as cellular respiration proceeds with the electron transport chain (step). Eventually, the oxygen is combined with the hydrogen ions initially released or split from glucose by the dehydrogenase enzyme. The reaction between oxygen and hydrogen ends up forming water.
Before starting the explanation in the amoeba sister video, they explain what DNA replication is. We can say that DNA, which in eukaryotic cells is located in the nucleus, contains all the genetic information of a being and its duplication process is important for cell growth, reproduction and repair.
<h3 /><h3>What is DNA replication?</h3>
A DNA molecule is made up of two strands that complement each other. For example, if we have an F and an F' strand, in the replication process the strands separate and are used as templates for the formation of complementary strands. Thus, the nucleotide sequence of F determines the sequence of a new F' strand, and F' indicates the composition of a new F strand.
<h3>DNA replication process</h3>
In the video of the amoebas sisters it is briefly explained that..
DNA replication occurs in the 5' → 3' direction and the strands are separated by the action of enzymes, which break the bonds between the nitrogenous bases and unwind the strands, opening the double helix.
As DNA uncoiling takes place, other enzymes act to catalyze the synthesis of two new sequences using the parent strands as a template. Each strand created joins an original strand of DNA. Therefore, the process is classified as semi-conservative.
DNA is a double helix molecule and for its duplication to occur, the first step is to unpack this structure by the action of the DNA helicase enzyme. The helicase recognizes the origin of replication and works by breaking the hydrogen bonds in the nitrogenous bases A-T and C-G. This process occurs at several points and forms "replication bubbles".
As the bonds unravel, it's like a zipper opening, so this step gives rise to a Y-shaped structure called the replication fork, the starting point of duplication.
The primase enzyme is responsible for synthesizing a portion of RNA, called a primer. In this step, several primers are generated and are joined to the chain to start DNA synthesis.
The DNA polymerase enzyme is the replication enzyme responsible for extending the new strand by adding the bases (A, C, G and T). This step is directed from the 5' end, with a phosphate group, to the 3' end, with a hydroxyl group. This phase is called continuous replication.
Among the primers attached to the original strand, several pieces of DNA are attached and are called Okazaki fragments. As the sections will need to be joined later, this phase is called delayed.
The exonuclease enzyme is responsible for removing the primers from the original strands after the formation of continuous and discontinuous strands. To avoid sequencing errors, a review and, if necessary, a correction is performed by another exonuclease.
The enzyme DNA ligase causes the DNA fragments to be joined and the DNA sequenced into two continuous strands.
thus, in a simple way, how DNA replication occurs in the video of the amoebas sisters.
