Reproduction is a characteristic of all living beings. It is fundamental to the maintenance of the species, since, under the present conditions of the earth, living beings arise only from other living beings like them through reproduction. At the molecular level, reproduction is related to the unique ability of DNA to duplicate.
In the cell that is in the process of division, each condensed chromosome appears as a pair of rods joined at one point, the centromere. These two chromosomal "halves", called sister chromatids, are identical and arise from the duplication of the original chromosomal filament that occurs at the interphase shortly before cell division begins.
The main consequence of meiosis, no doubt, is the emergence of diversity among individuals that are produced in the sexual reproduction of the species. The relationship between meiosis and variability is mainly based on the occurrence of crossing-over. Crossing is a phenomenon involving homologous chromatids.
Mitosis is a continuous process of cell division, but for didactic reasons, to better understand it, we will divide it into phases: prophase, metaphase, anaphase and telophase. Some authors often cite a fifth phase - the prometaphase - intermediate between prophase and metaphase. The end of mitosis, with the separation of the cytoplasm, is called cytokinesis.
RNA molecules are made up of a sequence of ribonucleotides, forming a single strand (strand). There are three basic types of RNA, which differ from each other in molecular weight: ribosomal RNA, represented by rRNA (or rRNA), messenger RNA, represented by mRNA (or mRNA) and carrier RNA, represented by tRNA (or tRNA) ).
A healthy diet should provide the body with adequate amounts of carbohydrates, lipids, proteins, vitamins, minerals and water. In addition to this general recommendation, care must be taken with the diet. Diet For a healthy diet it is recommended to: Consume vegetables, fruits and vegetables of the season (season), because they are generally fresher and cheaper; choose varied foods to ensure a balanced diet in nutrients, vitamins, water and minerals; give preference to natural, ie non-industrialized products; when it is not possible to avoid the consumption of processed foods, eat in small quantities and not repeat them for days at a time.
Vaccines are products made up of dead or attenuated (weakened) microorganisms or toxins produced by these inactivated microorganisms in the laboratory. Thus, vaccines contain antigens that are incapable of causing the disease but capable of inducing our bodies to produce antibodies. Thus, if the individual, after vaccination, comes into contact with these microorganisms, the body will already have enough antibodies for its defense. .
To meet the nutrient needs of our body, ie to be well fed, just eat enough. We should not exaggerate. When the body gets more energy than it spends, its weight increases. Obesity is usually a consequence of an excess of energy in the body in relation to the expenditure.
The connective tissue cells are spaced apart, and the space between them is filled with intercellular substance. The main function of connective tissue is to unite and support the organs of the body. This type of tissue has several cell groups that have their own characteristics. For this reason, it is subdivided into other tissue types.
To live, grow and maintain our bodies, we need to consume food. But what about the foods we eat? How do nutrients in food reach our body cells? To stay alive, continually renew cells, develop our bodies and maintain vital activities, we need food, as they provide energy to our body.
Urine is a clear, yellowish liquid formed in the kidneys that carries metabolism waste to the outside of the body. It consists of 95% water, in which urea, toxins and minerals such as chlorine, magnesium, potassium, sodium, calcium, among others (which form the remaining 5%), are dissolved.
Urine is approximately 95% water. The main excreta in human urine are: urea, sodium chloride and uric acid. The elimination of urine is done through the urinary system. The organs that make up the urinary system are the kidneys and the urinary tract. The urinary tract includes the ureter, bladder and urethra.
In the late nineteenth century several German scientists, namely Liebig, Richter and Helmholtz, attempted to explain the emergence of life on Earth with the hypothesis that it had been brought from another point in the universe in the form of resistant spores in meteorites - Cosmozoic theory. . The presence of organic matter in meteorites found on Earth has been used as an argument in favor of this theory, which does not invalidate the possibility of terrestrial contamination after the meteorite collapse.
Did you know that all of us were once a single cell? Looking at your body is hard to believe now, but we have all been a zygote, an egg cell. Speaking of sex In other times, sex was often a forbidden subject. At home, no one spoke "of these things." Among boys, information was usually passed on by older friends in hidden conversations.
Mineral salts are nutrients that provide sodium, potassium, calcium and iron. Contrary to popular belief, the water we drink is not absolutely pure. It contains small amounts of dissolved mineral salts. These salts also need to be replenished continuously. That's why dehydration can kill - acute mineral deficiency impairs metabolism, such as potassium deficiency, which can cause muscle paralysis, including heart muscle.
Already our skin allows us to perceive the texture of different materials, as well as the temperature of objects, the differences in pressure, capturing the variations of thermal energy and even the sensations of pain. We can feel the softness of a peach's outer shell, the warmth of a child's body that we hold in our lap, and the softness of the skin of a caressing body.
Long bones Note the following diagram, which shows the structure of a long bone. We can see that this bone has: Epiphyses - the ends of the bone, covered by cartilage; Periosteum - the fibrous membrane that lines the bone externally; Diaphysis - The portion of the bone between the epiphyses and surrounded by the periosteum.
The Peripheral Nervous System consists of nerves and nerve ganglia and its function is to connect the central nervous system to various parts of the human body. Nerves are bundles of nerve fibers surrounded by a layer of connective tissue. In the nerves there are blood vessels, responsible for the nutrition of nerve fibers.
What sets the time for drinking to be born? What determines that the mother produces milk to feed her baby? What indicates that people are no longer children and become sexually mature adults with male and female characteristics? What coordinates and integrates body functions and activities? All the functions and activities of our body are coordinated and integrated by the nervous system and the endocrine (hormonal) system.
See the list of scientific curiosities about friendship: TALKING BAD IS THE BEST DEAL If you are without friends, here's the first tip: Talking bad about others is the best way to make friends. Sounds poor, right? But it is real. American researchers asked some people to tell how their strongest friendships were born and how they acted when they were together with others (the strongest tendency was to speak ill of the people around them).
The spinal cord is an extension of the brain, extending from the base of the skull to just below the ribs. And a stem of brain tissue, with a small canal running through its entire length. The whole marrow is covered by membranes, like the brain, and is also bathed inside and out with the same protective fluid as the brain.