Energy for life One of the main limiting factors to the life of living beings is obtaining energy for their activities. According to heterotrophic theory, the first living beings would be heterotrophic prokaryotes living in an aquatic environment, from which they would draw nutrients, formed in the atmosphere and accumulated in the lakes and early oceans.
Mitochondrial Structure and Function Mitochondria are immersed in the cytosol, between the various sacs and filaments that fill the eukaryotic cell cytoplasm. They are true “powerhouses” of cells, as they produce energy for all cellular activities. Mitochondria were discovered in the mid-nineteenth century, and for decades their existence was questioned by some cytologists.
DNA controls all cellular activity. It has the "recipe" for the functioning of a cell. Every time a cell divides, the "recipe" must be passed to the daughter cells. The entire "file" containing information about cell functioning needs to be duplicated so that each child cell receives the same kind of information as the parent cell.
DNA differs from RNA in that it has deoxyribose sugar and the nucleotides adenine, cytosine, guanine and thymine. In RNA, sugar is ribose and nucleotides are adenine, cytosine, guanine, and uracil (uracil replaces thymine). DNA: A “Twisted Ladder” From experiments by several researchers and using the results of the complex X-ray diffraction technique, Watson and Crick concluded that in DNA, complementary strands are helical, suggesting the idea of a twisted ladder. .
It consists of the passage of the solute molecules from the largest to the lowest concentration until a balance is established. It is a slow process except when the concentration gradient is too high or the distances traveled are short. The passage of substances across the membrane occurs in response to the concentration gradient.
Prophase I - It is the most remarkable stage of meiosis. In it occurs the pairing of homologous chromosomes and can happen a phenomenon known as crossing-over (also called exchange). Since prophase I is long, there is a sequence of events that, for study purposes, can be divided into the following steps: Chromosomal spiraling begins.
Chromatin (from the Greek chromatos, color) is a collection of strands, each formed by a long DNA molecule associated with histone molecules, a special type of protein. These wires are the chromosomes. When nuclei stained under the light microscope are observed, certain regions of chromatin stain more intensely than others.
Process that occurs in the testicles, the male gonads. They secrete testosterone, the sex hormone responsible for the onset of male sexual characteristics: increased beard and body hair, more developed muscle mass, severe voice tone, etc. The cells of the testes are organized around the seminiferous tubules in which sperm are produced.
Vitamins are substances that the body is unable to produce and therefore need to be part of the diet. Its main sources are fruits, vegetables and legumes, but they are also found in meat, milk, eggs and cereals. Vitamins play several roles in development and organic metabolism.
Foods provide various substances that are the “raw material” for building cells. The cells produced allow the growth, development and maintenance of the body by replacing the dying cells. Foods also act as "fuels" in our bodies: Some molecules present in foods are "burned out" during cellular respiration and provide energy needed for organ activity.
In addition to the cardiovascular (circulatory) system for blood circulation, the human body has another fluid flow system: the lymphatic system. The lymphatic system comprises the set formed by the lymph, the lymphatic vessels and organs such as the lymph nodes, the spleen, the thymus and the palatine tonsils.
In the small intestine, most digestion of nutrients occurs as well as their absorption, that is, the assimilation of nutrients. In the duodenum, secretions from the liver and pancreas are released. In this first portion of the small intestine, chemical digestion is performed mainly - with the joint action of bile, pancreatic juice and enteric or intestinal juice acting on the chymus.
In our body there are many types of cells with different shapes and functions. Cells are organized into groups, which “working” in an integrated manner perform a particular function together. These cell groups are the tissues. Human body tissues can be classified into four main groups: epithelial tissue, connective tissue, muscle tissue, and nervous tissue.
Changes in the body The discovery of sex happens with the discovery of the body. Young men and boys often follow closely the changes that occur in their external sexual organs. These changes are caused by the action of hormones. Primary sexual characteristics, visible in the genitals, are genetically determined and present from birth in both men and women.
The bones of the upper and lower limbs attach to the axial skeleton through the joint girdles. Upper Limbs Composed of upper arm, forearm, wrist and hand. The arm has only one bone: the humerus, which is an upper limb bone. The forearm is composed of two bones: the radius, which is a long bone and which forms with the ulna (ulna) the skeleton of the forearm.
People can stay for a few seconds without breathing. It is also possible to breathe faster or slower. In these situations, breathing is controlled voluntarily, that is, as the person wishes, and activity of the diaphragm and intercostal muscles is regulated by a region of the person's brain.
You already know how fascinating ants are - they are very strong, they live in complex colonies and they know how to work together. But there are some awesome facts you don't know about them yet. See below. Cute? Beware, they practice slavery 1. There are very large ants out there. Forgive us if you have insect phobia, but one type of African ant, the Dorylus wilverthi, measures about two inches.
Adults are not alone in playing important roles in science. Discover some impressive discoveries made by children. Children, with their infinite curiosity and tendency to wander off limits, are also involved in scientific research and exploration. From spotting a supernova to digging up dinosaur bones, here are seven amazing discoveries made by children.
This means that you can be "full" even on an empty stomach. Just that your bacteria are already satisfied. A new study in France shows that intestinal bacteria Escherichia coli (E.coli) produce appetite-suppressing proteins 20 minutes after meals. They release proteins from satiety after they have enough nutrients for themselves.
Concern for the environment led the United Nations countries to sign an agreement stipulating control over human interventions in the climate. This agreement was born in December 1997 with the signing of the Kyoto Protocol. Accordingly, the Kyoto Protocol stipulates that developed countries that have signed the agreement reduce their greenhouse gas and greenhouse gas (GHG) emissions by 5.2% on average relative to the amount of gases emitted by the countries in the 1990, between 2008 and 2012.
We tend to use the word “animal” to shape gross or unreasonable behavior, but the ten facts below will change your mind about choosing that term in the future. After all, animals can be much more adorable than humans. For example: 10. Vampire Bats Love to Embrace You You probably don't know much about vampire bats, but you shouldn't think anything good about them either.