How would you feel sharing a toothbrush with the postman? What about drying your hands on a towel with a yellowish stain? Or, by touching greasy larvae of unknown insects? Your answer will probably be the same as anyone: disgust. But why? According to researchers at the London School of Hygiene and Tropical Medicine, this reaction may be common to the entire human species and play a key role in its evolution: disgust would be a protective mechanism against the threat of infectious disease.
It is located in the Arctic Circle. It comprises Northern Alaska and Canada, Greenland, Norway, Sweden, Finland, Siberia. It receives little solar energy and little precipitation, it usually occurs in the form of snow and the soil remains most of the year frosty. During the short warm season (2 months) melts the top, rich in organic matter, allowing the growth of vegetables.
Calcium is an element that participates in various structures of living beings, bones, shells, cell walls of plant cells, calcareous eggshells, and acts on some physiological processes, such as muscle concentration and blood coagulation in vertebrates. The main sources of this element are limestone rocks, which, over time, release it to the middle.
Food webs We may note, however, that the food chain does not show how complex trophic relationships in an ecosystem are. For this we use the concept of food web, which represents a true situation found in an ecosystem, ie several interconnected chains occurring simultaneously.
Ecological pyramids graph the flow of energy and matter between trophic levels along the food chain. For this, each rectangle represents, proportionally, the parameter to be analyzed. This graphical representation can be: Pyramid of numbers Represents the number of individuals in each food chain trophic level in proportion to the amount required for the diet of each of these.
This section is dedicated to teaching Biology (high school content). Click on the desired subject name to view its content. Introduction to Living Beings Classification of Living Beings Lineu and the Binomial System Popular Names Phylogeny Cladograms General Characteristics Prokaryotic, Eukaryotic and Incomplete Cells Animal Cell Plant Cell Viruses Viruses living or not?
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.
The solar energy captured by the producers dissipates along the food chains in the form of heat, an energy that is not usable by living beings. As this energy is dissipated by the ecosystem, permanent compensation occurs for the use of solar energy set by the producers, then passing through all other living elements of the ecosystem.
Cytology Cell membrane Glycalix Cellulosic wall Membrane proteins Plasma membrane transport Passive transport Active transport Endocytosis and exocytosis Cytoplasm Cyclosis Amoeboid movement Endoplasmic reticulum Vacuoles Golgi apparatus Peroxisomes Glycosomes Cytoskeleton Centroles Cilia and Flagella Mitochondrous Plasmas Chromosomes Plasmas Aroma nucleoli Chromosomes Genes and genome Cell division Mitosis of animal cell Mitosis in plant cell Cell cycle control Origin of cancer Meiosis Variability - crossing-over Gametogenesis Fertilization: back to diploidy Nucleic acids: cell control Replication Transcription The genetic code Translation Genic mutation Chemistry Carbohydrates Monosaccharides Oligosaccharides Polysaccharides Lipids Proteins Enzymes Food Proteins Nucleic Acid Composition Reproduction Reproduction ass exuada Sexual reproduction Fertilization types Sperm Eggs Ova Fertilization Embryology Embryonic development Stages of embryonic development Segmentation Gastrogenesis Protostomes and deuterostomes Celomata, acelomata and pseudocelomata Animals Embryonal attachments BIG BANG Evolution The formation of the Universe Abiogenesis Spontaneous generation Abiogenesis Abogenesis by Oparin Oparin Miller's experiment The evolution of metabolism Heterotrophic hypothesis Autotrophic hypothesis Multicellular life What is biological evolution?
Yeast and some bacteria ferment sugars, producing ethyl alcohol and carbon dioxide (CO 2), a process called alcoholic fermentation. In alcoholic fermentation, the two produced pyruvic acid molecules are converted into ethyl alcohol (also called ethanol), with the release of two CO 2 molecules and the formation of two ATP molecules.
Energy release through fermentation Fermentation is an energy release process that occurs without the participation of oxygen (anaerobic process). Fermentation comprises a set of enzymatically controlled reactions through which an organic molecule is degraded into simpler compounds, releasing energy.
In glycolysis there is a direct yield of two ATP molecules per degraded glucose molecules. Two NADH 2 molecules are also formed which, in the respiratory chain, provide energy for the synthesis of six ATP molecules. During the Krebs cycle, the two Acetyl-CoA molecules lead to the direct production of two ATP molecules.
Genetic improvement and artificial selection For centuries man has used the practice of genetic improvement to perfect animal and plant species of interest. It all began when man began to cross, followed by artificial selection, the varieties that interested him most. This procedure has given rise to countless animal breeds and plant varieties that are now part of our daily lives.
Gene therapy means the transfer of genetic material for the purpose of preventing or curing any disease. In the case of genetic disorders in which a gene is defective or absent, gene therapy consists of transferring the functional version of the gene to the disease-bearing organism in order to repair the defect.
This section is dedicated to science education (elementary school content). Click on the desired subject name to view its content. Universe Emergence of the Universe Stars Constellations Galaxy Solar System Planets Satellites Comets Asteroids Meteors The Moon Eclipses Air Carbonic Gas Nitrogen Noble Gases Water Steam Atmospheric Pressure Weather Forecast Air Masses Temperature and Humidity Meteorological Stations Air Pollution O Greenhouse Effect Thermal Inversion Water Physical States of Matter Physical State Changes Water Properties The Water Cycle The Water Quality Water Pollution Sources Treatment Stations Transmitted Diseases Water, Mosquito and Diseases The Planet Inside and Out Plate Tectonics Earthquakes Volcanoes Rocks, Minerals and Soil Magmatic or Igneous Rocks Sedimentary Rocks Metamorphic Rocks The Soil Cycle Soil Formation Soil Types Farming Agriculture Sustainable Agriculture Pollution Destination Soil Erosion Recycling Importance and Benefits Recycling Symbology recycling Paper recycling Glass recycling Metal recycling Plastic recycling Recycling batteries and batteries Recycling debris Tire recycling Non-recyclable materials Cooking oil recycling Ecology What does ecology study?
Origin of Life How Life Arose General Characteristics of Living Beings Cell Organization Cell Types Animal Cell Plant Cell Biodiversity Classification of Living Beings Evolution Fossils Vaccines and Serums Living Beings (Kingdoms) Monera Kingdom (Bacteria / Archaea) Protist Kingdom Kingdom of Fungi Kingdom Animal Invertebrates Porifers Cnidaria Platelminths Tapeworms Schistosomes Nematelmines Oxyuriasis Filariasis Ascariasis Hookworms Molluscs Arthropods Crustaceans Arachnids Kylopods Diplopods Insects Echinoderms Vertebrates Fishes Amphibians Reproductive Systems Humans Genitals Systems Foods Respiratory System Circulatory System Blood Groups Lymphatic System Excretory System Other Systems Nervous System E System ndocrine Anabolic Diabetes Skeletal System Skeletal Deformations Muscle System Cell Cell Division Human Body Organization Levels Tissues Organs Systems Sensory Organs Vision Visual Diseases Hearing Taste Physical Tact Introduction to Mechanics Weights and Measurements How to Divide Physics?
Structure and Origin of Lysosomes Lysosomes (from Greek lysis, breakage, destruction) are membrane pockets that contain enzymes capable of digesting organic substances. Originating in the Golgi apparatus, lysosomes are present in virtually all eukaryotic cells. The enzymes are produced in the RER and migrate to the dithiosomes, being identified and sent to a special region of the Golgi apparatus, where they are packaged and released in the form of small pouches.
All cells practice autophagy (from the Greek autos, self, and phagein, eating), digesting parts of themselves with the help of their lysosomes. Amazingly, autophagy is an indispensable activity for cell survival. In certain situations, autophagy is a purely food activity.
Centrioles are nonmembrane organelles that participate in the process of cell division. In complex fungal cells, superior plants (gymnosperms and angiosperms) and nematodes do not exist centrioles. They are present in most animal cells, algae and lower plants such as bryophytes (mosses) and pteridophytes (ferns).
The intermediate filaments are so named because they have an intermediate diameter - about 10 nm - relative to the other two types of protein filaments. In cells lining the outermost layer of the skin, there is a large amount of an intermediate filament type called keratin.
All mitochondria arise from the reproduction of another mitochondria. When the cell divides, its mitochondria separate into two roughly equivalent groups, which are positioned on either side of the cytoplasm. At the end of the division each group is in a daughter cell. Later, as cells grow, the mitochondria duplicate and grow, restoring the original number.