How many chromosomes does a caterpillar have. How many chromosomes does a cat have? Genetics provides data on various genomes. The number of chromosomes in different animals

​What mutations, besides Down's syndrome, threaten us? Is it possible to cross a human with a monkey? And what will happen to our genome in the future? The editor of the portal ANTROPOGENESIS.RU talked about chromosomes with a geneticist, head. lab. Comparative Genomics SB RAS Vladimir Trifonov.

- Can you explain in simple terms what a chromosome is?

- A chromosome is a fragment of the genome of any organism (DNA) in combination with proteins. If in bacteria the entire genome is usually one chromosome, then in complex organisms with a pronounced nucleus (eukaryotes) the genome is usually fragmented, and complexes of long DNA and protein fragments are clearly visible in a light microscope during cell division. That is why chromosomes as staining structures (“chroma” - color in Greek) were described as early as the end of the 19th century.

- Is there any connection between the number of chromosomes and the complexity of the organism?

- There is no connection. The Siberian sturgeon has 240 chromosomes, the sterlet has 120, but it is sometimes quite difficult to distinguish these two species from each other by external signs. Females of the Indian muntjac have 6 chromosomes, males have 7, and their relative, the Siberian roe deer, has more than 70 (or rather, 70 chromosomes of the main set and even up to a dozen additional chromosomes). In mammals, the evolution of breaks and mergers of chromosomes was quite intensive, and now we are observing the results of this process, when often each species has characteristic features of the karyotype (set of chromosomes). But, undoubtedly, the general increase in the size of the genome was a necessary step in the evolution of eukaryotes. At the same time, how this genome is distributed over individual fragments does not seem to be very important.

− What are the common misconceptions about chromosomes? People often get confused: genes, chromosomes, DNA...

- Since chromosomal rearrangements really often occur, people have concerns about chromosomal abnormalities. It is known that an extra copy of the smallest human chromosome (chromosome 21) leads to a rather serious syndrome (Down's syndrome), which has characteristic external and behavioral features. Extra or missing sex chromosomes are also quite common and can have serious consequences. However, geneticists have also described quite a few relatively neutral mutations associated with the appearance of microchromosomes, or additional X and Y chromosomes. I think the stigmatization of this phenomenon is due to the fact that people perceive the concept of the norm too narrowly.

- What chromosomal mutations are found in modern humans and what do they lead to?

- The most common chromosomal abnormalities are:

- Klinefelter's syndrome (XXY men) (1 in 500) - characteristic external signs, certain health problems (anemia, osteoporosis, muscle weakness and sexual dysfunction), sterility. There may be behavioral differences. However, many symptoms (except sterility) can be corrected by the administration of testosterone. With the use of modern reproductive technologies, it is possible to obtain healthy children from carriers of this syndrome;

- Down's syndrome (1 per 1000) - characteristic external signs, delayed cognitive development, short life expectancy, may be fertile;

- trisomy X (XXX women) (1 per 1000) - most often there are no manifestations, fertility;

- XYY syndrome (men) (1 in 1000) - almost no manifestations, but there may be behavioral features and reproductive problems are possible;

- Turner's syndrome (women CW) (1 per 1500) - short stature and other developmental features, normal intelligence, sterility;

- balanced translocations (1 per 1000) - depends on the type, in some cases malformations and mental retardation may be observed, may affect fertility;

- small extra chromosomes (1 in 2000) - the manifestation depends on the genetic material on the chromosomes and varies from neutral to severe clinical symptoms;

Pericentric inversion of chromosome 9 occurs in 1% of the human population, but this rearrangement is considered as a variant of the norm.

Is the difference in the number of chromosomes an obstacle to crossing? Are there any interesting examples of crossing animals with different numbers of chromosomes?

- If the crossing is intraspecific or between closely related species, then the difference in the number of chromosomes may not interfere with crossing, but the offspring may be sterile. A lot of hybrids are known between species with different numbers of chromosomes, for example, in horses: there are all variants of hybrids between horses, zebras and donkeys, and the number of chromosomes in all horses is different and, accordingly, hybrids are often sterile. However, this does not exclude the possibility that balanced gametes may be formed by chance.

- What unusual in the field of chromosomes has been discovered recently?

- Recently, there have been many discoveries regarding the structure, functioning and evolution of chromosomes. I especially like the work that has shown that the sex chromosomes formed in different groups of animals quite independently.

- But still, is it possible to cross a man with a monkey?

- It is theoretically possible to obtain such a hybrid. Recently, hybrids of much more evolutionarily distant mammals have been obtained (white and black rhinoceros, alpaca and camel, and so on). The red wolf in America has long been considered a separate species, but has recently been shown to be a hybrid between a wolf and a coyote. A huge number of feline hybrids are known.

- And a completely absurd question: is it possible to cross a hamster with a duck?

- Here, most likely, nothing will work out, because over hundreds of millions of years of evolution, too many genetic differences have accumulated for the carrier of such a mixed genome to be able to function.

- Is it possible that in the future a person will have fewer or more chromosomes?

- Yes, it is quite possible. It is possible that a pair of acrocentric chromosomes will merge and such a mutation will spread to the entire population.

- What popular science literature would you recommend on the topic of human genetics? What about popular science films?

− Books by the biologist Alexander Markov, the three-volume book “Human Genetics” by Vogel and Motulsky (although this is not pop-science, but there is good reference data there). From films about human genetics, nothing comes to mind ... But Shubin's "Inner Fish" is an excellent film and a book of the same name about the evolution of vertebrates.

Genetics is a science that studies the laws of heredity and variability of all living beings. It is this science that gives us knowledge about the number of chromosomes in different types of organisms, the size of chromosomes, the location of genes on them, and how genes are inherited. Genetics also studies mutations that occur during the formation of new cells.

Chromosomal set

Every living organism (the only exceptions are bacteria) has chromosomes. They are located in every cell of the body in a certain amount. In all somatic cells, chromosomes are repeated twice, thrice, or more times, depending on the type of animal or variety of plant organism. In germ cells, the chromosome set is haploid, that is, single. This is necessary so that when two germ cells merge, the correct set of genes for the body is restored. However, even in the haploid set of chromosomes, the genes responsible for the organization of the whole organism are concentrated. Some of them may not appear in the offspring if the second germ cell contains stronger features.

How many chromosomes does a cat have?

You will find the answer to this question in this section. Each type of organism, plant or animal, contains a certain set of chromosomes. The chromosomes of one species of creatures have a certain length of the DNA molecule, a certain set of genes. Each such structure has its own size.

And dogs are our pets? A dog has 78 chromosomes. Knowing this number, is it possible to guess how many chromosomes a cat has? It's impossible to guess. Because there is no relationship between the number of chromosomes and the complexity of the organization of the animal. How many chromosomes does a cat have? There are 38 of them.

Chromosome size differences

The DNA molecule, with the same number of genes located on it, can have different lengths in different species.

Moreover, the chromosomes themselves are of different sizes. One information structure can contain a long or very short DNA molecule. However, chromosomes are not too small. This is due to the fact that when the daughter structures diverge, a certain weight of the substance is necessary, otherwise the divergence itself will not occur.

The number of chromosomes in different animals

As mentioned above, there is no relationship between the number of chromosomes and the complexity of the organization of the animal, because these structures have a different size.

How many chromosomes a cat has, the same number of other cats: a tiger, a jaguar, a leopard, a cougar and other representatives of this family. Many canids have 78 chromosomes. So much for domestic chicken. The domestic horse has 64, and the Przewalski's horse has 76.

Humans have 46 chromosomes. The gorilla and chimpanzee have 48, while the macaque has 42.

A frog has 26 chromosomes. In the somatic cell of a pigeon there are only 16 of them. And in a hedgehog - 96. In a cow - 120. In a lamprey - 174.

Next, we present data on the number of chromosomes in the cells of some invertebrates. The ant, like the roundworm, has only 2 chromosomes in each somatic cell. A bee has 16 of them. A butterfly has 380 such structures per cell, and radiolarians have about 1600.

Animal data show different numbers of chromosomes. It must be added that Drosophila, which geneticists use in the course of genetic experiments, has 8 chromosomes in somatic cells.

The number of chromosomes in different plants

The plant world is also extremely diverse in terms of the number of these structures. So, peas and clover each have 14 chromosomes. Onion - 16. Birch - 84. Horsetail - 216, and fern about 1200.

Differences between males and females

Males and females at the genetic level differ in only one chromosome. In females, this structure looks like the Russian letter "X", and in males it looks like "Y". In some animal species, females have a "Y" chromosome, and males have an "X".

Traits found on such non-homologous chromosomes are inherited from father to son and from mother to daughter. The information that is fixed on the “Y” chromosome cannot be transferred to a girl, because a person who has this structure is necessarily male.

The same applies to animals: if we see a tricolor cat, we can say for sure that we have a female in front of us.

Because only the X chromosome, which belongs to females, has the corresponding gene. This structure is the 19th in the haploid set, that is, in germ cells, where the number of chromosomes is always two times less than in somatic ones.

The work of breeders

Knowing the structure of the apparatus that stores information about the body, as well as the laws of inheritance of genes and the features of their manifestation, breeders breed new plant varieties.

Wild wheat often has a diploid set of chromosomes. There are not many wild representatives that have a tetraploid set. Cultivated varieties often contain tetraploid and even hexaploid sets of structures in their somatic cells. This improves yield, weather resistance, and grain quality.

Genetics is an interesting science. The device of the apparatus containing information about the structure of the whole organism is similar in all living beings. However, each type of creature has its own genetic characteristics. One of the characteristics of a species is the number of chromosomes. In organisms of the same species, there is always a certain constant amount of them.

From school textbooks on biology, everyone had a chance to get acquainted with the term chromosome. The concept was proposed by Waldeyer in 1888. It literally translates as a painted body. The first object of research was the fruit fly.

General about animal chromosomes

The chromosome is the structure of the cell nucleus that stores hereditary information. They are formed from a DNA molecule, which contains many genes. In other words, a chromosome is a DNA molecule. Its quantity in different animals is not the same. So, for example, a cat has 38, and a cow has -120. Interestingly, earthworms and ants have the smallest number. Their number is two chromosomes, and the male of the latter has one.

In higher animals, as well as in humans, the last pair is represented by XY sex chromosomes in males and XX in females. It should be noted that the number of these molecules for all animals is constant, but for each species their number is different. For example, we can consider the content of chromosomes in some organisms: chimpanzee - 48, crayfish - 196, wolf - 78, hare - 48. This is due to the different level of organization of an animal.

On a note! Chromosomes are always arranged in pairs. Geneticists claim that these molecules are the elusive and invisible carriers of heredity. Each chromosome contains many genes. Some believe that the more of these molecules, the more developed the animal, and its body is more complex. In this case, a person should not have 46 chromosomes, but more than any other animal.

How many chromosomes do different animals have

Need to pay attention! In monkeys, the number of chromosomes is close to that of humans. But each type has different results. So, different monkeys have the following number of chromosomes:

• Lemurs have 44-46 DNA molecules in their arsenal;
• Chimpanzees - 48;
• Baboons - 42,
• Monkeys - 54;
• Gibbons - 44;
• Gorillas - 48;
• Orangutan - 48;
• Macaques - 42.

The family of canids (carnivorous mammals) has more chromosomes than monkeys.

• So, the wolf has 78,
• coyote - 78,
• in a small fox - 76,
• but the ordinary one has 34.
• The predatory animals of the lion and tiger each have 38 chromosomes.
• The cat's pet has 38, and its dog opponent has nearly twice as many, 78.

In mammals that are of economic importance, the number of these molecules is as follows:

• rabbit - 44,
• cow - 60,
• horse - 64,
• pig - 38.

Informative! Hamsters have the largest chromosome sets among animals. They have 92 in their arsenal. Also in this row are hedgehogs. They have 88-90 chromosomes. And the smallest number of these molecules are endowed with kangaroos. Their number is 12. A very interesting fact is that the mammoth has 58 chromosomes. Samples are taken from frozen tissue.

For greater clarity and convenience, the data of other animals will be presented in the summary.

The name of the animal and the number of chromosomes:

The number of chromosomes in different animal species

As you can see, each animal has a different number of chromosomes. Even among members of the same family, the indicators differ. Consider the example of primates:

• gorilla has 48,
• the macaque has 42, and the monkey has 54 chromosomes.

Why this is so remains a mystery.

How many chromosomes do plants have?

Plant name and number of chromosomes:

Video

Did Charles Darwin at the end of his life renounce his theory of human evolution? Did ancient people find dinosaurs? Is it true that Russia is the cradle of mankind, and who is the Yeti - is it not one of our ancestors who got lost in the centuries? Although paleoanthropology - the science of human evolution - is experiencing a rapid flowering, the origin of man is still surrounded by many myths. These are anti-evolutionary theories, and legends generated by mass culture, and pseudo-scientific ideas that exist among educated and well-read people. Do you want to know how it was "really"? Alexander Sokolov, editor-in-chief of the portal ANTROPOGENESIS.RU, has collected a whole collection of such myths and checked how well they are.

At the level of everyday logic, it is obvious that “a monkey is cooler than a person - it has two whole chromosomes more!”. Thus, “the origin of man from apes is finally refuted” ...

Let us remind our dear readers that chromosomes are the things in which DNA is packaged in our cells. A person has 23 pairs of chromosomes (23 we got from mom and 23 from dad. Total 46). The complete set of chromosomes is called a "karyotype". Each chromosome contains a very large DNA molecule tightly coiled.

It is not the number of chromosomes that matters, but the genes that these chromosomes contain. The same set of genes can be packed into different numbers of chromosomes.

For example, two chromosomes were taken and merged into one. The number of chromosomes has decreased, but the genetic sequence that is contained in them has remained the same. (Imagine that a wall was broken between two neighboring rooms. One large room turned out, but the content - furniture and parquet - is the same ...)

The fusion of chromosomes occurred in our ancestor. That is why we have two fewer chromosomes than chimpanzees, despite the fact that the genes are almost the same.

How do we know about the closeness of human and chimpanzee genes?

In the 1970s, when biologists learned to compare the genetic sequences of different species, they did this for humans and chimpanzees. Specialists were in for a shock: “ The difference in the nucleotide sequences of the substance of heredity - DNA - in humans and chimpanzees as a whole was 1.1%,- wrote the famous Soviet primatologist E. P. Fridman in the book "Primates". - ... Frog species or squirrels within the same genus differ from each other 20–30 times more than chimpanzees and humans. It was so surprising that I had to urgently somehow explain the discrepancy between molecular data and what is known at the level of the whole organism.» .

And in 1980 in an authoritative magazine Science University of Minneapolis genetics team published The Striking Resemblance of High-Resolution G-Banded Chromosomes of Man and Chimpanzee.

The researchers used the latest methods of coloring chromosomes at that time (transverse stripes of different thickness and brightness appear on the chromosomes; at the same time, each chromosome differs in its own special set of stripes). It turned out that in humans and chimpanzees, the striation of chromosomes is almost identical! But what about the extra chromosome? And it’s very simple: if we put the 12th and 13th chromosomes of a chimpanzee in one line opposite the second human chromosome, connecting them at the ends, we will see that together they make up the second human.

Later, in 1991, researchers looked at the point of the alleged fusion on the second human chromosome and found there what they were looking for - DNA sequences characteristic of telomeres - the terminal sections of chromosomes. Another proof that there were once two in place of this chromosome!

But how does such a merger take place? Suppose one of our ancestors had two chromosomes combined into one. He got an odd number of chromosomes - 47, while the rest of the non-mutated individuals still have 48! And how did such a mutant then multiply? How can individuals with different numbers of chromosomes interbreed?

It would seem that the number of chromosomes clearly distinguishes between species and is an insurmountable obstacle to hybridization. What was the surprise of the researchers when, studying the karyotypes of various mammals, they began to find a scatter in the number of chromosomes within some species! So, in different populations of the common shrew, this figure can vary from 20 to 33. And the varieties of the musk shrew, as noted in the article by P. M. Borodin, M. B. Rogacheva and S. I. Oda, “differ from each other more than a person from a chimpanzee: animals living in the south of Hindustan and Sri Lanka , have 15 pairs of chromosomes in the karyotype, and all other shrews from Arabia to the islands of Oceania - 20 pairs ... It turned out that the number of chromosomes decreased because five pairs of chromosomes of a typical species merged with each other: 8th with 16th, 9? I am from the 13th, etc.”

Mystery! Let me remind you that during meiosis - cell division, as a result of which sex cells are formed - each chromosome in the cell must connect with its homologue pair. And here, when merged, an unpaired chromosome appears! Where should she go?

It turns out the problem is solved! PM Borodin describes this process, which he personally registered in 29 chromosome punares. Punare are bristly rats native to Brazil. Individuals with 29 chromosomes were obtained by crossing between 30 and 28 chromosome punare belonging to different populations of this rodent.

During meiosis in such hybrids, paired chromosomes successfully found each other. “And the remaining three chromosomes formed a triple: on the one hand, a long chromosome received from a 28 chromosome parent, and on the other, two shorter ones that came from a 30 chromosome parent. In this case, each chromosome stood in its place"