In 1949, English researcher Murray Barr discovered that there is a difference between the interphase nuclei of male and female cells: on the periphery of female mammalian cell nuclei there is a mass of chromatin that does not exist in male cells. This chromatin makes it possible to identify the cellular sex of individuals by simply examining the interphase nuclei: it is called Barr's sexual chromatin or corpuscle.
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In the ovaries are cell clusters called Graff's ovarian follicles, where are the germ cells, which originate the gametes, and the follicular cells, responsible for maintaining the germ cells and the production of female sex hormones. In women, only one ovarian follicle matures at each menstrual cycle, a period between two consecutive menstruations and lasting on average 28 days.
The Structure of Chromosomes Interphase Cell Chromosomes The life span of the cell in which it is not in the process of dividing is called interphase. Interphase cell chromatin, as already mentioned, is a mass of filaments called chromosomes. If we could separate the chromosomes one by one from a human interphase cell, we would get 46 filaments, logos and fines.
The most well-known lipids are represented by oils and fats and basically have energetic function, just like carbohydrates. Oil and fat molecules are formed by the union of two smaller molecules, fatty acid and glycerol. Lipids also have structural function, they participate in the constitution of cell membranes.
It is also called a cell membrane, cytoplasmic membrane or plasmalema. The whole cell, whether prokaryote or eukaryote, has a membrane that isolates from the outside: the plasma membrane. This membrane is so thin (between 6 and 9 nm) that the finest optical microscopes could not make it visible.
The safe supply of blood from a donor to a recipient requires knowledge of blood groups. We will study two blood group classification systems in humans: the ABO and Rh systems. In humans there are the following basic blood types in relation to ABO systems: group A, group B, group AB, and group O.
The earth is home to over 7 billion human beings. Each person is a unique being, different from all other beings in many ways, as is the case with outward appearance. But the human body is made up of basically the same structures and we are all influenced by the environment in which we live. This influence comes from the social environment, the culture of which we are part and also from the affective relationships we experience.
In some cells, processes occur that allow particles (solid or liquid) to enter the external medium into the cell. These processes are generically called endocytosis and usually occur in cells that constitute unicellular organisms living in the aqueous medium. Some cells of multicellular organisms can also perform these processes, but in this case the function is not food but defense.
The heart, blood vessels and blood form the cardiovascular or circulatory system. Blood circulation allows the transport and distribution of nutrients, oxygen gas and hormones to the cells of various organs. The blood also carries waste metabolism so it can be eliminated from the body.
White blood cells or leukocytes are the body's defense cells that destroy foreign agents, for example bacteria, viruses, and toxic substances that attack our bodies and cause infections or other diseases. Leukocyte is a compound word of Greek origin meaning "white cell": leuko means "white" and cyto "cell".
Nerve tissue cells are called neurons, which are capable of receiving stimuli and conducting information to other cells through the nerve impulse. Neurons have star shape and are specialized cells. In addition, nerve tissue also has other cell types, such as glial cells, whose function is to nourish, sustain, and protect neurons.
Life on Earth was probably about 3400 M.a., as the prokaryote fossils found in South Africa seem to show. Eukaryotic cells appeared about 2000 to 1400 M.a., followed by multicellular organisms about 700 M.a. In this time the fossils are abundant, indicating a rapid evolutionary process.
Breathing occurs day and night without stopping. We can survive for a while without food, but we can't breath without more than a few minutes. Do you know that all living beings need energy to live and that energy is obtained from food? Our body gets energy from food through the process of cellular respiration, performed in mitochondria, with the participation of oxygen gas obtained in the environment.
Think about how many movements you perform every day, from the time you wake up to the time you go to sleep again. You get out of bed, brush your teeth, take breakfast foods to your mouth, chew, go to school, come back, do gymnastics, run, use your hands to hold something, stroll, sneeze, yawn, push and pull objects, rehearsing dance steps while listening to music, playing basketball, playing any other sport… Skeleton Function The adult human skeleton consists of about 200 bones.
The spindle fibers begin to shorten. As a result, each batch of sister chromosomes is pulled to opposite poles of the cell ("ana" indicates backward movement). As each chromid becomes a new chromosome, it can be considered that the cell is temporarily tetraploid. Telophase - End Phase (telos = end) Chromosomes initiate the despiration process.
In our relationship with the world, we are stimulated all the time and respond to the elements of the environment. With each external stimulus (such as the smell of food or the sound of a horn) and even internal stimulus (such as pain or hunger), the organism reacts, that is, in a way “answers these questions: Where does the stimulus?
The animal kingdom is really fascinating. There are millions of species of animals on the planet, and many of them we don't even know exist either because they are endangered or far from our eyes. It is always good to know a little more about these species, how they live, where they can be found and how they behave in nature.
There are many things I see beauty in: a cheerful choreography, a striking song or an intriguing face. But I can't always consciously explain why I consider them beautiful. The spiders of the genus Maratus are also like this. Males have a beautiful colored abdomen that they exhibit when doing a complicated dance.
Most of us find our first gray hair in our early thirties, usually at the temples, and later all over the scalp. While many people find the gray look appealing, others are dedicated to hiding these signs. Dermatology professor at Melbourne University Epworth Hospital Rodney Sinclair explains in an article published on The Conversation that the “golden rule” of gray hair is that at age 50, half the population loses their hair. color on 50% of your hair.
Although the human race can boast of having the most developed brain of all species on earth, in terms of strength, size and speed, we all lose ugly. Also, some animals are so poisonous that a sting is enough to kill dozens of people. Most animals have some kind of defensive or predatory system.