How many chromosomes does a person have. How many chromosomes do different animals have

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, consider the content of chromosomes in some organisms: chimpanzee - 48, crayfish -196, wolf - 78, hare - 48. This is due to different levels 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 types animals

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

genetic research human body are among the most necessary for the population of the entire planet. It is genetics that is of great importance for the study of the causes of hereditary diseases or predisposition to them. We will tell how many chromosomes does a person have and what this information might be useful for.

How many pairs of chromosomes does a person have

The cell of the body is designed to store, implement and transmit hereditary information. It is made up of a DNA molecule and is called a chromosome. Many are interested in the question of how many pairs of chromosomes a person has.

Humans have 23 pairs of chromosomes. Until 1955, scientists erroneously counted the number of chromosomes as 48, i.e. 24 couples. The error was discovered by scientists using a more precise technique.

The set of chromosomes is different in somatic and germ cells. The doubled (diploid) set is present only in the cells that determine the structure (somatics) of the human body. One part is maternal, the other part is from the father.

Gonosomes (sex chromosomes) have only one pair. They differ in the composition of their genes. Therefore, depending on gender, a person has a different composition of a pair of gonosomes. From that how many chromosomes do women have the sex of the unborn child does not depend. A woman has a set of XX chromosomes. Her germ cells do not affect the laying of sexual characteristics during the fertilization of the egg. Belonging to a particular gender depends on the information code about how many chromosomes does a man have. It is the difference between the XX and XY chromosomes that determines the sex of the unborn child. The remaining 22 pairs of chromosomes are called autosomal, i.e. the same for both sexes.

• A woman has 22 pairs of autosomal chromosomes and one pair of XX;
• A male has 22 pairs of autosomal chromosomes and one XY pair.

According to their structure, chromosomes change during division in the process of duplication of somatic cells. These cells are constantly dividing, however, a set of 23 pairs has a constant value. DNA influences the structure of chromosomes. The genes that make up the chromosomes, under the influence of DNA, form a certain code. Thus, the information obtained in the process of DNA coding determines the individual characteristics of a person.

Changes in the quantitative structure of chromosomes

The human karyotype determines the totality of chromosomes. Sometimes it can be modified under the influence of chemical or physical causes. The normal number of 23 chromosomes in somatic cells may vary. This process is called aneuploidy.

1. The number may be less, then it is monosomy.
2. If there is no pair of authentic cells, then this structure is called nullisomy.
3. If a pair of cells that make up a chromosome has a third added, then it is a trisomy.

Various changes in the quantitative set leads to a person getting congenital diseases. Anomalies in the structure of chromosomes cause Down syndrome, Edwards syndrome and other conditions.

There is also a deviation called polyploidy. With this deviation, a multiple increase in chromosomes occurs, that is, a doubling of a pair of cells that is part of one chromosome. A diploid or germ cell can be presented three times (triploidy). If it is presented 4 or 5 times, then such an increase is called tetraploidy and pentaploidy, respectively. If a person has such a deviation, then he dies during the first days of life. The plant world is quite widely represented by polyploidy. A multiple increase in chromosomes is present in animals: invertebrates, fish. Birds with such an anomaly die.

If we consider the organism at the cellular level, its structural unit is the chromosome, which contains genes. Such Greek word Literally translated as "body coloring". This means that during cell division, the chromosomes are stained in the presence of natural dyes. In fact, this is a valuable carrier of information, and the discrepancy between the chromosome number indicates the course of the pathological process.

How many chromosomes does a normal person have

According to statistics, 1% of all newborns appear with physiological abnormalities against the background of an incomplete genetic series. That is why doctors are so puzzled global problem with health, in world practice, it is studied at the cellular level. So, in a healthy body, there are 23 pairs of chromosomes, that is, 46 units. Until 1955, scientists had no doubt that there were only 24 such pairs. The well-known scientist Theophilus Painter made a mistake in the calculation, and other luminaries of medicine, Jo-Hin Tjo and Albert Levan, corrected it.

General information about the chromosome set

It is important to understand that the morphological features of chromosomes are the same, while somatic and germ cells have a different chromosome set. Graduates explain in detail what the differences are:

1. Sex cells (gametes) have a haploid set of chromosomes, and in case of successful fertilization, the male and female gametes combine in one zygote. Differences in chromosomes are structural, morphological, for example, in women, a couple of XX, in men - XY.
2. Somatic cells have a diploid set of chromosomes, i.e. doubled, divided into classic pairs - male and female cage. Chromosomes are similar in size and morphological features.

Morphological changes in chromosomes are observed during cell division, when their total number doubles. Despite such numerous processes, the total number of pairs remains unchanged. The health and intellectual development of a person depends on the number of chromosomes, so doctors begin to seriously deal with such a global issue even when planning a pregnancy. That is why the gynecologist strongly recommends visiting a geneticist, conducting a number of clinical studies if necessary.

One chromosome from a pair goes to a person from the biological mother, the other from the father, and the 23rd pair determines the sex of the unborn child. The feminine is characterized by the symbolic combination XX, and the masculine by XY. Studying the human karyotype, it is necessary to explain that in the chromosome set of a healthy person there are 22 pairs of autosomes, plus one female, one male chromosome (sex). By studying the totality of features of a chromosome within a single cell, it is possible to determine the human karyotype with certainty. If there is a violation of the karyotype, its owner is expected to have serious health problems.

Potential problems at the gene level

In fact, there may be several problems, and each is considered as an individual clinical picture. Possible pathologies are presented below, do not lend themselves successful treatment after the birth of a sick child. It:

1. Aneuploidy is a pathological process with a violation of the number of individual chromosomes.
2. Monosomy is a pathological process in the absence of a homologous chromosome.
3. Polyploidy is an abnormal phenomenon when the number of haploid sets exceeds diploid ones.
4. Trisomy - the presence of an extra chromosome, tetrasomy - two.

Such conditions are not an indicator of the norm, they can be determined even in the prenatal period. Doctors recommend that a pregnant woman have an abortion, otherwise the newborn will be born with serious health problems. This is an absolute contraindication to childbirth, otherwise a woman will have to raise a disabled person all her life.

How many chromosomes does a person with Down syndrome have?

Not always the number of pairs of chromosomes meets the standards of the norm. The problem is discovered by a geneticist when a pregnant woman comes for a voluntary examination. The disturbed number of chromosomes determines health problems, among which doctors distinguish:

• Down's disease;
• Klinefelter's syndrome;
• Shereshevsky-Turner syndrome.

It is not possible to replenish the genetic series with conservative methods, and diagnoses by their nature are already considered incurable. If a health problem is identified in the prenatal period, the expectant mother is recommended to terminate the pregnancy. At the same time, they explain that otherwise a sick child will be born, external deformities are not excluded.

More about Down Syndrome

Separately, it is worth describing Down's syndrome, which was first diagnosed in the 17th century. It was very problematic to determine the number of pairs of chromosomes at that time, and the number of sick children was frightening with numbers. So, for 1,000 babies, there were 2 patients with Down syndrome. Later, the disease was studied at the genetic level and it was determined what happens to the chromosome set.

It turns out that another chromosome is attached to the 21st pair, which makes the total number of chromosomes - 47. The pathological process is characterized by its spontaneous formation, and its development is preceded by such anomalies as diabetes, increased dose of radiation, advanced age of biological parents, the presence of certain chronic diseases.

A child with Down syndrome has external differences from healthy children. Among these are a narrow and wide forehead, large ears, a voluminous tongue, and obvious mental retardation. In addition to visual signs, the patient has serious health problems affecting all internal organs and systems.

It remains only to add that the chromosome number of the unborn child for the most part depends on the mother's genome. Therefore, before planning a pregnancy, it is advisable to undergo a complete clinical examination, in a timely manner to identify the hidden problems of your own body. Only in the absence of contraindications can one think about a successful conception and a bright future for the child.

Sometimes they give us amazing surprises. For example, do you know what chromosomes are and how they affect?

We propose to understand this issue in order to dot the i's once and for all.

When looking at family photos, you might have noticed that members of the same kinship look alike: children look like parents, parents look like grandparents. This similarity is passed down from generation to generation through amazing mechanisms.

All living organisms, from single-celled to African elephants, have chromosomes in the cell nucleus - thin long threads that can only be seen with an electron microscope.

Chromosomes (ancient Greek χρῶμα - color and σῶμα - body) are nucleoprotein structures in the cell nucleus, in which most of the hereditary information (genes) is concentrated. They are designed to store this information, its implementation and transmission.

How many chromosomes does a person have

As early as the end of the 19th century, scientists found that the number of chromosomes in different species is not the same.

For example, peas have 14 chromosomes, y - 42, and in humans - 46 (i.e. 23 pairs). Hence, it is tempting to conclude that the more there are, the more complex the creature that possesses them. However, in reality this is not at all the case.

Of the 23 pairs of human chromosomes, 22 pairs are autosomes and one pair are gonosomes (sex chromosomes). Sexual have morphological and structural (composition of genes) differences.

In a female organism, a pair of gonosomes contains two X chromosomes (XX pair), and in a male organism, one X and one Y chromosome (XY pair).

It is on what will be the composition of the chromosomes of the twenty-third pair (XX or XY) that the sex of the unborn child depends. This is determined during fertilization and the fusion of the female and male reproductive cells.

This fact may seem strange, but in terms of the number of chromosomes, a person is inferior to many animals. For example, some unfortunate goat has 60 chromosomes, and a snail has 80.

Chromosomes consist of a protein and a DNA (deoxyribonucleic acid) molecule, similar to a double helix. Each cell contains about 2 meters of DNA, and in total there are about 100 billion km of DNA in the cells of our body.

An interesting fact is that in the presence of an extra chromosome or in the absence of at least one of the 46, a person has a mutation and serious developmental abnormalities (Down's disease, etc.).

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, Chief Editor portal ANTROPOGENESIS.RU, collected a whole collection of such myths and checked how well-founded 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"