Discovery[ edit ] InBarbara McClintocka distinguished American cytogeneticist and the first woman to receive an unshared Nobel Prize in Physiology or Medicine, observed that the chromosomes lacking end parts became "sticky" and hypothesized the existence of a special structure at the chromosome tip that would maintain chromosome stability.
Learn more about this article Human beings, humans, or Homo sapiens sapiens Homo sapiens is latin and refers to the wise or knowing human are bipedal primates in the family Hominidae.
DNA evidence indicates that modern humans originated in Africa aboutyears ago. Humans have a highly developed brain, capable of abstract reasoning, language, introspection, and emotion. This mental capability, combined with an erect body carriage that frees the forelimbs arms for manipulating objects, has allowed humans to make far greater use of tools than any other species.
Humans currently inhabit every continent on Earth, except Antarctica although several governments maintain seasonally-staffed research stations there. Humans also now have a continuous presence in low Earth orbit, occupying the International Space Station.
The human population on Earth is greater than 6.
Like most primates, humans are social by nature. However, they are particularly adept at utilizing systems of communication for self-expression, exchanging of ideas, and organization.
Humans create complex social structures composed of many cooperating and competing groups, from families to nations. Social interactions between humans have established an extremely wide variety of traditions, rituals, ethics, values, social norms, and laws, which together form the basis of human society.
Humans have a marked appreciation for beauty and aesthetics, which, combined with the desire for self-expression, has led to innovations such as culture, art, literature and music. Humans are notable for their desire to understand and influence the world around them, seeking to explain and manipulate natural phenomena through science, philosophy, mythology and religion.
This natural curiosity has led to the development of advanced tools and skills; humans are the only currently known species known to build fires, cook their food, clothe themselves, and manipulate and develop numerous other technologies. Humans pass down their skills and knowledge to the next generations through education.
The scientific study of human evolution encompasses the development of the genus Homo, but usually involves studying other hominids and hominines as well, such as Australopithecus. Modern humans are defined as the Homo sapiens species, of which the only extant subspecies - our own - is known as Homo sapiens sapiens.
Homo sapiens idaltu roughly translated as elder wise humanthe other known subspecies, is now extinct. Anatomically modern humans first appear in the fossil record in Africa aboutyears ago, although studies of molecular biology give evidence that the approximate time of divergence from the common ancestor of all modern human populations wasyears ago.
The closest living relatives of Homo sapiens are the two chimpanzee species: Full genome sequencing has resulted in the conclusion that after 6. It has been estimated that the human lineage diverged from that of chimpanzees about five million years ago, and from that of gorillas about eight million years ago.
However, a hominid skull discovered in Chad inclassified as Sahelanthropus tchadensis, is approximately seven million years old, which may indicate an earlier divergence. The Recent African Origin RAOor the - out-of-Africa- hypothesis proposes that modern humans evolved in Africa before later migrating outwards to replace hominids in other parts of the world.
Evidence from archaeogenetics accumulating since the s has lent strong support to RAO, and has marginalized the competing multiregional hypothesis, which proposed that modern humans evolved, at least in part, from independent hominid populations.
They also propose that during the Late Pleistocene, the human population was reduced to a small number of breeding pairs, no more than 10, and possibly as few as 1, resulting in a very small residual gene pool.
Various reasons for this hypothetical bottleneck have been postulated, one being the Toba catastrophe theory. Human evolution is characterized by a number of important morphological, developmental, physiological and behavioural changes, which have taken place since the split between the last common ancestor of humans and chimpanzees.
The first major morphological change was the evolution of a bipedal locomotor adaptation from an arboreal or semi-arboreal one, with all its attendant adaptations, such as a valgus knee, low intermembral index long legs relative to the armsand reduced upper-body strength.
The pattern of human postnatal brain growth differs from that of other apes heterochronyand allows for extended periods of social learning and language acquisition in juvenile humans. Physical anthropologists argue that the differences between the structure of human brains and those of other apes are even more significant than their differences in size.
Other significant morphological changes included:Large stretches of DNA in the human genome are transcribed but do not code for proteins. These regions are called introns and make up around 95% of the genome. The nucleotide sequence of the human genome is now known to a reasonable degree of accuracy but we do not yet understand why so much of .
An In-depth Look at the 7 Major Steps of DNA Replication The process of DNA replication comprises a set of carefully orchestrated sequence of events to duplicate the entire genetic content of a cell.
The current article provides a short insight into the complex DNA replication steps. In , researchers completed the first full sequence of the human genome, according to a report by the National Human Genome Research Institute.
DNA testing A person's DNA contains information about their heritage, and can sometimes reveal whether they are at risk for certain diseases.
Internet-Based Tools for Teaching Transcription and Translation. Transcription is the process of making an RNA copy of a gene sequence. This copy, called a messenger RNA (mRNA) molecule, leaves the cell nucleus and enters the cytoplasm, where it directs the synthesis of the protein, which it encodes. Sep 25, · Each chromosome is made up of DNA tightly coiled many times around proteins called histones that support its structure. Chromosomes are not visible in the cell’s nucleus—not even under a microscope—when the cell is not dividing. [Related: Unraveling the Human Genome: 6 Molecular Milestones] DNA sequencing. DNA sequencing is technology that allows researchers to determine the order of bases in a DNA sequence.
A DNA helix usually does not interact with other segments of DNA, and in human cells, the different chromosomes even occupy separate areas in the nucleus called "chromosome territories".
Nov 13, · The information in DNA is stored as a code made up of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T).
Human DNA consists of about 3 billion bases, and more than 99 percent of those bases are the same in all people. The project's goals included: mapping the human genome and determining all billion letters in it, mapping and sequencing the genomes of other organisms, if it would be useful to the study of biology, developing technology for the purpose of analysing DNA and studying the social, ethical and legal implications of genome research.