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 strongest, the oldest, the loudest, the most poisonous, etc. In this section, we present several curiosities about the animal kingdom, both in Brazil and in the world. Older Animals passed from sea to land 414 million years ago. The world's first land animals include two types of centipedes and a small spider found among plant debris.
Why do we hiccup? The hiccup is the result of an involuntary contraction of the diaphragm, a thin muscle that separates the thorax from the abdomen and which, together with the external intercostal muscles, is responsible for breathing control. Their contraction and relaxation movements allow us to breathe in and out and are controlled by the phrenic nerve just above the stomach.
How old are we growing up? How do we get old? What are we made of? Why do people die? In this section, we present various curiosities about the human body. Why do we lose milk teeth? From birth, the roots of the milk teeth and the definitive teeth are within the gums.
In the animal world, there are many questions that hammer our heads and one of them is: why do roosters always sing in the morning? So many hours for them to sing, what makes them always choose the same time? Anyone who has had the opportunity to witness in person knows that it works like a clock.
All because of a reduction in solar activity At the National Astronomy Meeting, researchers made predictions that we may have a mild ice age by 2030. The study, announced by Professor Valentina Zharkova of the University of Northumbria, was based on computer models of sunspots - according to her, the model would be extremely accurate, with 97% hits by mapping previous movements of solar activity.
Puft! You gone. What would be the consequences if the same thing happened to all human beings on earth at exactly the same moment? This imaginative experience not only explores the impact humanity has on the planet, but also the incredible resilience of nature. The ASAP Science YouTube channel has decided to answer this question.
In our daily lives, we often come across hygiene habits that we have acquired from children, according to our parents' guidelines, or even during the experiences (good or bad) we have been through. On the other hand, there are those who do not care much about these issues. For example, do you wash your hands regularly?
We know that some animals do not have real teeth consisting of enamel and dentin. Many have tooth-like structures but different constitutions. However, there are animals that have neither, and have developed different mechanisms to obtain food. The best known of these is the anteater, which has long and sticky tongue, but unlike other mammals, has no teeth.
There are many creatures in nature that have developed ingenious defense mechanisms. See: 1 - The lizard that exudes blood through the eyes The lizard in the image below - of the species Phrynosoma cornutum -, besides having horns, has developed a defense mechanism beyond unusual. This reptile, no larger than 60 centimeters in length, is capable of throwing blood through the eyes to scare off its predators.
In real life, there are actually some people who dress differently and patrol the streets on their own, occasionally fighting crime. But is it possible for a true comic book hero to exist in real life? The 10 superheroes below could be saving the planet now, or sometime in the future.
Although today's humans are the result of thousands of years of evolution, do not think that we are the end product of the development of our species. Although it may not seem so, the truth is that our bodies and behaviors are still undergoing transformations and adapting to the environment in which we live.
In food chains we find animals that feed on plants: they are called herbivorous animals. Other animals eat herbivores: they are carnivores. And yet there are carnivores that eat other carnivores and animals that eat both plants and other animals, being called omnivores. All these organisms that feed on other beings are called consumers.
Interspecific (between individuals of different species) Mutualism Association between individuals that may be obligatory (symbiosis) or optional (protocooperation). In the obligatory association, both individuals benefit, but each species can only live in the presence of the other. Eg lichen, oxen and microorganisms of the digestive system.
Relationship in which an animal captures and kills individuals of another species to feed. Eg: snake and rat, man and cattle. All carnivores are predatory animals. This is what happens with the lion, the wolf, the tiger, the jaguar, who hunt deer, zebras and so many other animals. The predator can also attack and devour plants, such as the grasshopper, which, in flocks, quickly devour an entire plantation.
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.
Due to the difference in calf distribution, there are two basic types of meroblastic segmentation: discoidal and superficial. In discoid meroblastic segmentation, the divisions occur only in the region of the scar (region of the cell without calf), forming a disk of cells over the calf mass.
The action of natural selection consists in selecting individuals more adapted to a given ecological condition, eliminating those disadvantaged for that same condition. The most appropriate expression refers to the greater likelihood of a given individual surviving and leaving offspring in a given environment.
The comparison between DNA molecules of different species has revealed the degree of similarity of their genes, which shows the evolutionary relationship. The same is true for proteins that ultimately reflect genetic similarities and differences. Cytochrome c is a protein present in all living beings that do aerobic respiration, consisting of 104 chained amino acids.
Between living beings and the environment in which they live there is a fit, a fundamental harmony for survival. The pink flamingo, for example, lowers its head to the swampy ground where it lives to fetch its food there; hummingbirds with their long beaks are adapted to collect nectar from the tubular flowers they visit.
We have so far analyzed the emergence of the first living forms, and you may have noticed that we have already mentioned, for these forms, some important characteristics for conceptualizing a living being. These early organisms have organic compounds in the constitution of their bodies, are cellular (unicellular in this case) and have reproductive capacity.