Scheme of chromosome structure in late prophase and metaphase of mitosis. 1 chromatid; 2 centromeres; 3 short shoulder; 4 long shoulder ... Wikipedia
I Medicine Medicine is a system of scientific knowledge and practical activities, the goals of which are to strengthen and preserve health, prolong the life of people, prevent and treat human diseases. To accomplish these tasks, M. studies the structure and... ... Medical encyclopedia
The branch of botany concerned with the natural classification of plants. Specimens with many similar characteristics are grouped into groups called species. Tiger lilies are one type, white lilies are another, etc. Species similar to each other, in turn... ... Collier's Encyclopedia
ex vivo genetic therapy- * ex vivo gene therapy * gene therapy ex vivo gene therapy based on the isolation of the patient’s target cells, their genetic modification under cultivation conditions and autologous transplantation. Genetic therapy using germline... ... Genetics. encyclopedic Dictionary
Animals, plants and microorganisms are the most common objects of genetic research.1 Acetabularia acetabularia. A genus of unicellular green algae of the siphon class, characterized by a giant (up to 2 mm in diameter) nucleus... ... Molecular biology and genetics. Dictionary.
Polymer- (Polymer) Definition of polymer, types of polymerization, synthetic polymers Information about the definition of polymer, types of polymerization, synthetic polymers Contents Contents Definition Historical background Science of Polymerization Types ... ... Investor Encyclopedia
A special qualitative state of the world is perhaps a necessary step in the development of the Universe. A naturally scientific approach to the essence of life is focused on the problem of its origin, its material carriers, the difference between living and nonliving things, and evolution... ... Philosophical Encyclopedia
Chromosomes are a nuclear structure that carries embedded genetic information in the genus of genes (DNA). Geneticists are studying this direction and know how many chromosomes does a monkey have, how much does a person have and .
DNA contains hereditary data intended for transmission and storage. Everyone knows from school biology courses that humans have 23 pairs of chromosomes, making a total of 46. Some believe that monkeys and humanity are not far from each other in development.
The strangest thing is chimpanzees have 48 chromosomes, only two less than a human. There is a study proving that in the process of human evolution, a pair of diverse chromosomes became one chromosome. How does this happen? Read on.
In the 70s of the last century, the similarities between human and monkey chromosomes were studied. Primatologist Friedman wrote that the difference in the nucleotide chains of the gene sequence between chimpanzees and humans was 1.1%.
A little later, in the 80s, one very popular magazine called “Science” published an article from a group of geneticists at a university in Minneapolis. At that time, scientists used new technologies for studying chromosomes.
Geneticists stained chromosomes, and transverse stripes of varying brightness and thickness appeared on them, and each chromosome showed its own individuality and uniqueness, because it had its own set of such stripes.
As you probably already understood, the chromosomes of humans and monkeys were “distributed”. Studies have shown that we have the same striations! What about the extra chromosome?
The fact is that if you look opposite the second chromosome and imagine the twelfth and thirteenth monkey chromosomes in one line, then putting their ends together, it turns out that together they form the second human chromosome.
There is further evidence that a pair of chromosomes was once missing in humans. They conducted another experiment in the 90s, which showed that if you look at the point of supposed unification on the 2nd human chromosome, scientists saw that the DNA has a terminal section of chromosomes that are characteristic of the so-called telomeres.
It has been confirmed that it is the number of chromosomes that sets the boundaries between species, and it is this number that prevents further hybridization and change in species. When scientists began to study the karyotypes of various mammals, they discovered that the number of chromosomes varied!
For example, Rogacheva and Borodin noted that at different territorial sites the same animals have different numbers of chromosomes! So, for example, the shrew living in Sri Lanka has fifteen pairs of chromosomes (thirty in total), and in Arabia - twenty pairs of chromosomes (forty in total). As it was discovered later, several chromosomes became smaller because chromosomes merged.
It turns out that if during meiosis, and this is cell division during which new germ cells are formed, each chromosome must unite with its homologous pair. In the human body, one chromosome is produced, which turns out to be unpaired.
Borodin's theory
The same scientist Borodin, mentioned above in the article, says that he himself conducted some experiment that confirms this theory. Borodin checked that the so-called Punare (rat) had twenty-nine chromosomes. Why did this happen?
It turns out that there was a crossing between two populations of rodents that had thirty and twenty-eight chromosomes. Borodin wrote: “The three chromosomes that remained formed a trio of chromosomes.
On one side there is a long chromosome that came from the twenty-eighth parent, and on the second side there are two much shorter chromosomes that came from the thirty-chromosomal parent.
It turns out that all the chromosomes have found their place.” Here is the material on the topic: how many chromosomes does a monkey have.
How did this erroneous figure come about? First, only those regions of DNA that encode proteins were compared. and this is only a tiny part (about 3%) of the total DNA. In other words, the comparison simply ignored the remaining 97% of the DNA volume! So much for the objectivity of the approach! Why were they initially ignored? The fact is that evolutionists considered non-coding sections of DNA to be “junk”, that is, "useless remnants of past evolution". And this is where the evolutionary approach failed. Behind last years science has discovered important role non-coding DNA: she regulates the work of genes encoding proteins, “turning them on” and “turning them off.” (Cm. )
The myth of 98-99% genetic similarity between humans and chimpanzees is still widespread these days.
It is now known that differences in gene regulation (which are often difficult to even quantify) are as important a factor in determining the differences between humans and apes as the sequence of nucleotides in genes itself. It is not surprising that large genetic differences between humans and chimpanzees continue to be found in initially ignored non-coding DNA. If we take it into account (i.e. the remaining 97%), then the difference between us and chimpanzees increases to 5–8%, and perhaps 10–12% (research in this area is still ongoing).
Secondly, the original work did not directly compare DNA base sequences, but a rather crude and imprecise technique was used, called DNA hybridization: individual sections of human DNA were combined with sections of chimpanzee DNA. However, in addition to similarity, other factors also influence the degree of hybridization.
Third, in the initial comparison, the researchers only took into account base substitutions in DNA, and did not take into account inserts, which contribute greatly to genetic variation. In one comparison of a given section of chimpanzee and human DNA, taking into account insertions, a difference of 13.3% was found
The bias of evolutionists and the belief in a common ancestor played a significant role in obtaining this false figure, which significantly slowed down the receipt of a real answer to the question of why humans and apes are so different.
Therefore evolutionists forced believe that for some unknown reasons, hyperfast evolution occurred on the branch of transformation of ancient apes into humans: random mutations and selection supposedly created for a limited number of generations complex brain, a special foot and hand, an intricate speech apparatus and other unique human properties (note that the genetic difference in the corresponding sections of DNA is much greater than the general 5%, see examples below). And this is while we know from actual living fossils, .
So, there was stagnation in thousands of branches (this is an observed fact!), and in the human family tree there was an explosive hyper-fast evolution (never observed)? This is simply unrealistic fantasy! The evolutionary belief is untrue and contradicts everything science knows about mutations and genetics.
- The human Y chromosome is as different from the chimpanzee Y chromosome as it is from the chicken chromosome. In a recent comprehensive study, scientists compared the human Y chromosome with the chimpanzee Y chromosome and found that they "surprisingly different". One class of sequences within the chimpanzee Y chromosome differed by more than 90% from a similar class of sequences within the human Y chromosome, and vice versa. And one class of sequences in the human Y chromosome in general "had no counterpart in the chimpanzee Y chromosome". Evolutionary researchers expected the Y chromosome structures to be similar in both species.
- Chimpanzees and gorillas have 48 chromosomes, while we only have 46. Interestingly, potatoes have even more chromosomes.
- Human chromosomes contain genes that are completely absent in chimpanzees. Where did these genes and their genetic information come from? For example, chimpanzees lack three important genes that are associated with development inflammatory process when a person reacts to illness. This fact reflects the difference that exists between the immune systems of humans and chimpanzees.
- In 2003, scientists calculated a difference of 13.3% between the regions responsible for immune systems. 19 The FOXP2 gene in chimpanzees is not speech at all, but performs completely different functions, exerting different effects on the functioning of the same genes.
- The section of human DNA that determines the shape of the hand is very different from the DNA of chimpanzees. Interestingly, differences were found in non-coding DNA. The irony is that evolutionists, guided by their belief in evolution, considered such sections of DNA to be “junk” - “useless” remnants of evolution. Science continues to discover their important role.
- At the end of each chromosome is a strand of repeated DNA sequence called a telomere. In chimpanzees and other primates there are about 23 kb. (1 kb is equal to 1000 nucleic acid base pairs) repeating elements. Humans are unique among all primates in that their telomeres are much shorter, only 10 kb long. This point is often silent in evolutionary propaganda when discussing the genetic similarities between apes and humans.
@Jeff Johnson, www.mbbnet.umn.edu/icons/chromosome.html
In a recent comprehensive study, scientists compared the human Y chromosome with the chimpanzee Y chromosome and found they were “surprisingly different.” One class of sequences within the chimpanzee Y chromosome was less than 10% similar to a similar class of sequences within the human Y chromosome, and vice versa. And one class of sequences on the human Y chromosome “had no analogue on the chimpanzee Y chromosome.” And in order to explain where all these differences between humans and chimpanzees come from, proponents of large-scale evolution are forced to invent stories about rapid, complete rearrangements and the rapid formation of DNA containing new genes, as well as regulatory DNA. But since each corresponding Y chromosome is unique and completely dependent on the host organism, it is most logical to assume that humans and chimpanzees were created in a special way - separately, as completely different creatures.
Important to remember, different kinds organisms differ not only in their DNA sequence. As evolutionary geneticist Steve Jones said: “50% of human DNA is similar to bananas, but this does not mean that we are half bananas, either from head to waist or from waist to toe.”.
That is, the evidence indicates that DNA is not everything. For example, mitochondria, ribosomes, endoplasmic reticulum and cytosol are passed unchanged from parents to offspring (protection against possible mutations in mitochondrial DNA). And even gene expression itself is controlled by the cell. Some animals have undergone incredibly strong genetic changes, and yet their phenotype remains virtually unchanged.
This evidence provides tremendous support for reproduction “after its own kind” (Genesis 1:24–25).
Differences in behavior
To introduce you to the many abilities we often take for granted,
Studying monkeys allows scientists to make discoveries that have implications for the entire world of creatures on the planet. Specialists study not only individual behavioral signs. Geneticists delve deeply into questions about the chromosomal structure of animals. The question of how many chromosomes monkeys have in relation to other animals is of paramount importance to researchers.
How many chromosomes does a monkey have?
The hereditary material that is part of the nucleus of a eukarytic cell of an organism is called a chromosome. Strands of chromosomes form DNA. The functions of the molecule include storing and transmitting information about certain properties inherent in each type (karyotype) of the organism. Chimpanzees have the closest structure to human DNA. This species of monkey has 48 chromosomes or 24 pairs of cells. For comparison, humans have 46 chromosomes. Some researchers claim that the chimpanzee genome is 97.4% identical to humans.
Other primates have their own karyotype structure (number of chromosomes):
- Macaques - 42.
- Gibbons – 44.
- Monkeys - 55-71.
- Howler monkeys – 42-50.
According to one version, which supports the origin of humans from monkeys, chromosomal changes occurred during the process of mutation about 6 million years ago. According to the researchers, under the influence of external factors, two chromosomes merged into one and two different karyotypes were formed, human and chimpanzee. Apes and humans are united in the hominid family.
The smallest genetic variations are found in humans. Therefore, chromosomal changes and inbreeding are often problematic. The genetic similarity of two unrelated people is greater than that of chimpanzees from the same family. Therefore, the biblical descent of people from Adam and Eve is in some way valid. There is very little genetic diversity among humans, despite differences in external signs: skin color, eyes, height, build.
At the moment, experts refute the similarity of the human and chimpanzee genomes, and as a result, the version of a common ancestor. Interestingly, the DNA of humans and bananas is 50% identical. But this does not mean that our body and banana DNA once had a common relative. For example, the DNA of a human and a mouse is 98% the same, and a dog is 95% identical. On the other hand, it is genetic similarity that allows humanity to discover new drugs that create a revolution in pharmacology. With the help of experimental research, more and more powerful remedies against serious diseases are being created.
Currently, numerous studies are being carried out on the DNA of chimpanzees and humans. Opponents of the DNA match theory argue that in fact the differences between the genomes are about 19%. That is, in reality the similarity is no more than 81%, and according to some sources it is much less.
Geneticists have adopted the term effective population size. It indicates the number of individuals required to transfer all the genetic material. According to research, about 15,000 people are needed to preserve human genetic information, no more than 0.02% of the entire population. In mice, the effective population size is 733,000 individuals. Thus, genetic similarity is not a determining factor in the claim that humans and chimpanzees once shared a common ancestor. Disputes on this issue have not subsided to this day.
A vote for a post is a plus for karma! :)
One of the popular arguments of creationists goes like this: great apes- chimpanzees, gorillas and orangutans - 2 more chromosomes than humans. How did it happen that during the process of evolution, humans lost chromosomes? Is something similar happening here now? Why might people not suspect that they are mutants? How do these mutants reproduce?
Comparison of human and chimpanzee chromosomes. It can be seen that the 2nd human chromosome corresponds to the 2nd chimpanzee chromosomes. Source: Jorge Yunis, Science 208:1145-58 (1980). Courtesy of Science magazine.
Let us remind our dear readers that chromosomes are the things in which DNA is packaged in our cells. Humans have 23 pairs of chromosomes: 23 chromosomes we got from our mother and 23 from our father. Total 46. For chimpanzees - 24+24=48. The complete set of chromosomes is called a "karyotype". Each chromosome contains a very large DNA molecule, tightly coiled. In fact, it is not the number of chromosomes that is important, but the genes that these chromosomes contain. The same set of genes can be packaged into different numbers of chromosomes.
In 1980, an article by a team of geneticists at the University of Minneapolis was published in the authoritative journal Science. The researchers used the latest chromosome coloring methods at that time (transverse stripes of different thicknesses and brightness appear on the chromosomes, with each chromosome distinguished by its own special set of stripes). It turned out that in humans and chimpanzees the chromosome striations are almost identical! But what about the extra chromosome in monkeys? It’s all very simple: if, opposite the second human chromosome, we put the 12th and 13th chimpanzee chromosomes in one line, connecting them at their ends, we will see that together they make up the second human chromosome.
Later, in 1991, scientists took a closer look at the point of the putative fusion on the second human chromosome and found there what they were looking for - DNA sequences characteristic of telomeres - the end sections of chromosomes. A year later, traces of a second centromere were found on the same chromosome (a centromere is a region necessary for normal cell division. A centromere usually divides a chromosome into two parts, called arms; each chromosome has only one active centromere). Obviously, in place of one chromosome there used to be two. So, once upon a time in our ancestors, two chromosomes merged into one, forming the 2nd human chromosome.
How long ago did this happen? Now that paleogeneticists have learned to reconstruct the genomes of fossil creatures, we know that both Neanderthal and Denisovan man several tens of thousands of years ago already had 46 chromosomes, just like us. According to modern data, the merger occurred much earlier, in the range of 2.5-4.5 million years ago. In order to determine the date more accurately, it would be good to obtain the genomes of Heidelberg man and Homo erectus, as well as completely reconstruct the corresponding chromosomes of modern apes.
But the question arises: let’s say that one of our ancestors had two chromosomes combined into one. He ended up with an odd number of chromosomes - 47, while the rest of the non-mutated individuals still had 48! And how did such a mutant then reproduce? How can individuals with different numbers of chromosomes interbreed? Let me remind you that during meiosis - cell division, which results in the formation of sex cells - each chromosome in the cell must connect with its homologue pair. And then an unpaired chromosome appeared! Where should she go?
But it turns out that this is not a problem if, during meiosis, homologous regions of chromosomes find each other. In the case of an odd number of chromosomes, some germ cells may carry an “unbalanced” genetic makeup due to incorrect chromosome segregation in meiosis, but others may turn out quite normal.
When crossing a 47-chromosomal mutant with a 48-chromosomal “wild” individual, some of the children will turn out to be normal, 48-chromosomal (24 + 24), and some will be 47-chromosomal (23 from the mutant parent + 24 from the normal one). As a result, several individuals with an odd number of chromosomes appear. All they have to do is meet - and voila: in the next generation, 46-chromosomes (23+23) appear. Experts believe that the further spread of the 46-chromosome type could have occurred due to certain evolutionary advantages that arose as a result of this mutation. Chromosome fusion led to the loss or change in the functioning of genes located near the fusion point. This may be due to increased fertility or enhanced cognitive abilities (studies show that several genes located near the chromosomal fusion point are expressed in the brain, as well as in the gonads of men).
Model of a "gorilla-like" polygynous clan of early Homo, where the male (or male) had a chromosome fusion. Squares - males, circles - females. A male with a mutation (II generation), owner of 47 chromosomes, had children from several females (III generation). As a result, some of his descendants turned out to be 48-chromosomal (unshaded), some were 47-chromosomal (half-shaded), in addition to being sick and dead due to chromosome imbalance (black triangles). In the fourth generation, as a result of crossing two carriers of the mutation, 46-chromosomal variants are obtained (fully filled circle and square).
Someone will say that this is all fantasy. However, chromosome fusion occurs in humans even now, as a result of a common mutation - Robertsonian translocation (abbreviated as ROB).
If you have seen a chromosome in a picture, then you can imagine that it often looks like two “arms” extending from one point - (this point is the centromere). Sometimes the arms are the same length - such a chromosome is called metacentric. If the arms are unequal, the chromosome is submetacentric. And if one of the arms is so short that it is almost invisible, the chromosome is acrocentric.
So, in ROB, two acrocentric chromosomes break at the centromere and their long arms fuse to form a new single chromosome. The short arms also join together to form a small chromosome, which is usually lost within a few cell divisions. So there is one less chromosome. In this case, a small chromosome contains so little genetic material that it can disappear without any noticeable effect on the individual. Everything would be fine, only the body ended up with an odd set of chromosomes (22+23=45 instead of 46).
Robertsonian translocations are not such a rare event. 45 chromosomes are found in every 1000th newborn child. In humans, ROB can affect acrocentric chromosomes 13, 14, 15, 21 and 22. Most ROB carriers are completely healthy and are unaware of it until they are trying to have children. But problems may not arise - in which case the mutation will be passed on from generation to generation, unnoticed by anyone.
What is the chance of two such mutants meeting and giving birth to a 44-chromosomal child? This would seem to be a very unlikely event. However, in small human populations, marriages between relatives - such as cousins - are not uncommon. In this case, crossing two ROB carriers is quite possible. Such stories have been known to geneticists for many decades. Here are just two of them.
The fact of transmission of the mutation for at least 9 generations was recorded in 1987. ROBs were found in three Finnish families going back to a common ancestor. The genealogy of the families could be traced back to the beginning of the 18th century, when their ancestors lived in 3 villages in the north of what is now Finland, not far from each other. The largest of the families contained at the time of the study at least 49 carriers of fused chromosomes 13 and 14. Among them there was also a homozygote for the mutation, the owner of 44 chromosomes - a woman whose parents were second cousins. Except for her small height, 152 cm, she was healthy and gave birth to 6 children! An amazing woman died at the age of 63 from cardiac arrest.
Another case was recorded in 2016 in China. The story goes like this: a 25-year-old Chinese man married a young woman; they had a son, but died 6 months old. In this regard, doctors did a genetic analysis. It turned out that the deceased child had 45 chromosomes, the mother was normal, but the father had 44 chromosomes. Further investigation revealed that the man's parents were cousins, both ROB carriers. Their chromosomes 14 and 15 merged into one. Specialists decided to conduct a full examination of the unique patient. First, he was examined by a psychiatrist and a neurologist, who did not reveal any abnormalities. Then the man had a brain tomogram, an electroencephalogram and even a lumbar puncture - everything was fine, the “mutant” was as healthy as a bull. Next, scientists studied the sperm of both the man himself (44 chromosomes) and his father (45 chromosomes). In the father, 20% of the sperm were unbalanced, but in the son, 99.7% of the sperm were quite normal. So, our 44-chromosomal male is healthy and ready to reproduce. Of course, as we see, when he married a woman who was a carrier of a normal karyotype, he encountered difficulties. But if he came across a homozygous ROB just like him, everything would be perfect.
According to the study authors, the reproductive barrier between ROB and ordinary people, theoretically, could lead to the formation of an isolated population of 44-chromosome individuals interbreeding with each other. And this is the path to the emergence of something new subspecies Homo sapiens.