1.2.1. Primary bioelements

Primary bioelements

If the chemical composition of living matter (biosphere) is compared with that of the atmosphere, hydrosphere and lithosphere, which are the three layers that living beings occupy, the following conclusions can be drawn:

In the biosphere we will find a high amount of H and O because living matter is made up of water in a percentage that varies between 65% (terrestrial organisms) to 90% (aquatic organisms). All chemical reactions that take place in living beings develop in water, so the existence of living matter without water is not possible. All of this indicates that life originated in water.
The rest of the primary bioelements (C, N, S and P) of the biosphere are not so abundant in the atmosphere, hydrosphere or lithosphere, so it can be deduced that living matter has not been formed from the most common elements. abundant, but from those (C, H, O, N, P and S) that thanks to their properties are capable of constituting it. These properties are:
- Their atomic mass is relatively small, which favors the establishment of stable covalent bonds when combined. The smaller an atom, the greater the tendency of the positive nucleus to complete its last orbital with the electrons that form the bonds, and, therefore, the more stable these bonds are.
- Oxygen and nitrogen are highly electronegative elements, so when they join covalently with other atoms, they often give rise to dipole molecules. As water is also dipolar, these compounds dissolve well in it and can react with each other, making possible the biochemical processes essential for life.

The rest of the properties are not common, so they are discussed separately below.

Carbon

It is the basic skeleton of all organic biomolecules and makes the difference between organic and inorganic matter.

It has four electrons in its outermost shell and can form covalent bonds with other carbons, which allow it to form long chains of atoms (macromolecules). These bonds can be single (C-C), double (C=C) or triple (C≡C). It can also bind to the different radicals formed by the other elements (-H, = O, -OH, -NH₂, -SH, -H₂PO₄, etc.), thus allowing a large number of different molecules, that will intervene in a multitude of chemical reactions, and, thus, be able to take advantage of the great diversity of elements that exist in the environment.

Carbono tetraédrico

By Andreza Memelli (Own work) [Public domain], via Wikimedia Commons

The four covalent bonds form, in space, the vertices of an imaginary tetrahedron, allowing the formation of three-dimensional structures, such as the plasma membrane or other organelles.

The carbon also allows other macromolecule, the DNA, can contain all the information necessary to produce other molecules of the body and replicate to transmit that information to their descendants, being essential for life.

Biological song: The carbon cycle (The frustrating journey of a carbon atom). Julinky.

Hydrogen

Together with oxygen, it is essential to form organic matter, which is defined as the matter basically made up of carbon and hydrogen.

For example, some lipids are only made up of carbon and hydrogen atoms. The same as oil and its derivatives (butane, gasoline, diesel, etc.), consisting only of carbon and hydrogen, which is why they are called hydrocarbons.

The electron in the hydrogen atom allows it to bind to any of the other primary bioelements. The covalent bonds that forms between hydrogen and carbon is strong enough to be stable, but not strong enough to prevent it from breaking, thus allowing the synthesis of other molecules. Molecules made up of only carbon and hydrogen are nonpolar covalents (insoluble in water).

Oxygen

It is the most electronegative primary bioelement, so when it binds with hydrogen, it attracts its only electron, originating electrical poles. Therefore, the radicals -OH, -CHO and -COOH are polar radicals. When these radicals replace some hydrogens of a chain of carbons and hydrogens, such as glucose (C₆H₁₂O₆), they originate soluble molecules in polar liquids such as water.

Due to its electronegativity, oxygen has a great capacity to attract electrons from other atoms, leaving them oxidized. As this process involves the breaking of bonds and the release of a large amount of energy, the reaction of carbon compounds with oxygen, called aerobic respiration, is the most common way to obtain energy. The other route, fermentation, has been declining since algae and plants, through photosynthesis, began to enrich the primitive atmosphere with oxygen.

The oxidation of biological compounds is basically carried out by subtracting hydrogens from carbon atoms. Oxygen (more electronegative) attracts the electron from hydrogen more strongly than carbon, so it is able to remove it. Thus water is formed (oxygen plus hydrogen) and a large amount of energy is released, which living beings take advantage of. As the carbon atom goes from sharing an electron with hydrogen, to sharing fewer electrons with oxygen, it experiences a "loss" of electrons, that is, it oxidizes:

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy

Nitrogen

The nitrogen has a great facility for forming compounds with both hydrogen (NH₃) as with oxygen (NO^-), allowing, to the switch from one form to another, the release of energy.

It is found in amino acids (molecules that make up proteins) forming amino groups (-NH₂) and in the nitrogenous bases of nucleic acids. Although nitrogen is the most abundant gas in the atmosphere, very few organisms are able to take advantage of it. Virtually all nitrogen is incorporated into living matter by algae and plants, which absorb it dissolved in the form of nitrate ion (NH₃^-).

Sulfur

It is found in the form of the sulfhydryl radical (-SH) in certain amino acids such as cysteine and methionine. These radicals make it possible to establish, between two nearby amino acids, strong covalent bonds called disulfide bridges (-SS-), which maintain the protein structure.

Phosphorus

It is very important because it forms energy-rich bonds. By breaking the bond that joins two phosphate groups -PO₃^- ~ PO₃^- ~ PO₃^2-, generally of a molecule called ATP (adenosine triphosphate), the energy contained in said bond is released. The energy released in other reactions, such as oxidations of respiration, is stored in these bonds.

In addition, phosphorus is very important because it is part of the nucleic acids (DNA and RNA), of the phospholipids of the plasma membrane and of the bones of vertebrates, and because it helps to keep the acidity of the internal environment of the body constant.

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Skip navigation Biology 2nd Baccalaureate Biology 2nd Bac. 1. Bioelements and biomolecules. Water and mineral salts 1.1. Chemical bonds in biology 1.1.1. Intramolecular bonds 1.1.1.1. Covalent bond 1.1.1.2. Ionic bond 1.1.2. Intermolecular bonds 1.1.2.1. Van der Waals forces 1.1.2.2. Hydrogen bonds 1.2. The chemical basis of life: inorganic and organic components 1.2.1. Primary bioelements 1.2.2. Secondary bioelements 1.2.3. Trace elements 1.3. The immediate principles or biomolecules 1.3.1. Water 1.3.1.1. Chemical structure of water 1.3.1.2. Properties and functions of water 1.3.2. Mineral salts 1.3.2.1. Functions of salts in solution 1.3.2.2. Colloidal solutions and dispersions 1.3.2.3. Properties of colloidal dispersions 1.3.2.4. Diffusion, osmosis and dialysis 1.3.2.4.1. Diffusion 1.3.2.4.2. Osmosis 1.3.2.4.3. Dialysis 1.4. Bibliography 2. Glucides 2.1. Glucid concept 2.2. Classification of carbohydrates 2.3. Monosaccharides 2.3.1. Trioses 2.3.1.1. Spatial isomerism or stereoisomerism 2.3.2. Tetroses 2.3.3. Pentoses 2.3.3.1. Monosaccharide cyclization 2.3.4. Hexoses 2.4. The N-glucosidic and O-glucosidic bonds 2.4.1. Substances derived from monosaccharides 2.5. Disaccharides 2.6. Polysaccharides 2.6.1. Homopolysaccharides 2.6.1.1. Reserve homopolysaccharides 2.6.1.2. Structural homopolysaccharides 2.6.2. Heteropolysaccharides 2.6.3. Heterosides 2.7. General functions of glucides 2.8. Bibliography 3. Lipids 3.1. Lipid concept 3.2. Classification of lipids 3.2.1. Fatty acids 3.2.1.1. Saturated and unsaturated fatty acids 3.2.1.2. Chemical properties of fatty acids 3.2.1.3. Physical properties of fatty acids 3.2.1.4. Fatty Acid Functions 3.2.2. Saponifiable lipids or with fatty acids 3.2.2.1. Simple lipids 3.2.2.1.1. Acylglycerides 3.2.2.1.2. Cerides 3.2.2.2. Complex lipids 3.2.2.2.1. Phospholipids 3.2.2.2.2. Glycolipids 3.2.3. Unsaponifiable lipids or without fatty acids 3.3. Lipid functions 3.4. Bibliography 4. Proteins 4.1. Introduction to proteins 4.2. Amino acids 4.2.1. Classification of amino acids 4.2.2. Properties of amino acids 4.3. The peptide bond 4.4. Protein 4.4.1. Protein structure 4.4.1.1. Primary structure of proteins 4.4.1.2. Secondary structure of proteins 4.4.1.3. Tertiary structure of proteins 4.4.1.4. Quaternary structure of proteins 4.4.2. Protein properties 4.4.3. Classification of proteins 4.4.3.1. Holoproteins 4.4.3.2. Heteroproteins 4.4.4. Protein functions 4.5. Enzymes 4.5.1. Structure of enzymes 4.5.2. The active center of enzymes 4.5.3. General Mechanism of Enzyme Catalysis 4.5.4. Regulation of enzyme activity 4.5.5. Allosteric enzymes 4.5.6. Nomenclature and classification of enzymes 4.6. The vitamins 4.6.1. Fat-soluble vitamins 4.6.2. Water soluble vitamins 4.7. Bibliography 5. Nucleotides and nucleic acids 5.1. The chemical composition of nucleic acids 5.1.1. Components of nucleic acids 5.1.2. Concept, types and functions of nucleic acids 5.1.3. Nucleosides 5.1.4. Nucleotides 5.1.4.1. Nucleotide functions 5.1.5. Nucleic acids 5.2. Deoxyribonucleic acid (DNA) 5.2.1. DNA structure 5.2.1.1. Primary structure of DNA 5.2.1.2. Secondary structure of DNA 5.2.1.3. Tertiary structure of DNA 5.2.1.3.1. Tertiary structure of DNA in prokaryotes 5.2.1.3.2. Tertiary structure of DNA in eukaryotes 5.2.1.4. Quaternary structure of DNA 5.2.2. DNA types 5.2.3. Genetic material: chromatin and chromosomes 5.2.3.1. Karyotype and karyogram 5.3. Ribonucleic acid (RNA) 5.3.1. RNA types 5.3.1.1. Transfer RNA 5.3.1.2. Messenger RNA 5.3.1.3. Ribosomal RNA 5.3.1.4. Nucleolar RNA 5.3.1.5. Small nuclear RNA 5.3.2. Functions of ribonucleic acids 5.4. Bibliography 6. Cell morphology 6.1. Cell concept 6.1.1. Cell history 6.1.2. Cell theory 6.2. Levels of cellular organization 6.2.1. General characteristics of cells 6.2.2. Prokaryotic cells 6.2.2.1. Prokaryotic cell morphology 6.2.2.2. Structure of prokaryotes 6.2.2.2.1. Bacterial capsule 6.2.2.2.2. Bacterial wall 6.2.2.2.3. Plasma membrane 6.2.2.2.4. Cytoplasm-Ribosomes-Inclusions 6.2.2.2.5. Bacterial DNA 6.2.2.2.6. Bacterial appendages 6.2.2.3. Bacteria Physiology 6.2.3. Eukaryotic cells 6.2.3.1. Animal and plant cell 6.2.3.1.1. Animal eukaryotic cell 6.2.3.1.2. Plant eukaryotic cell 6.2.3.2. Cell Evolution: Endosymbiont Theory 6.3. Size, shape and quantity 6.4. The plasma membrane 6.4.1. Chemical composition of the membrane 6.4.2. The structure of the membrane. The fluid mosaic model 6.4.3. Functions of the plasma membrane 6.4.4. Transport across the membrane 6.4.4.1. Small molecule transport 6.4.4.2. Macromolecule transport 6.4.5. Plasma membrane differentiations 6.5. The cell wall of plant cells 6.5.1. Chemical composition of the cell wall 6.5.2. Cell wall structure 6.5.3. Cell wall differentiations 6.5.4. Cell wall functions 6.6. Extracellular matrix or glucocalyx 6.7. Cytosol or hyaloplasm 6.8. The cytoskeleton 6.8.1. Microfilaments or actin filaments 6.8.2. Intermediate filaments 6.8.3. Microtubules 6.9. Cell membrane and organelle systems 6.9.1. Membrane systems 6.9.1.1. The endoplasmic reticulum 6.9.1.2. Golgi apparatus 6.9.2. Cell organelles 6.9.2.1. Lysosomes 6.9.2.2. Peroxisomes 6.9.2.3. Vacuoles 6.9.2.4. Mitochondria 6.9.2.4.1. Functions of the mitochondria 6.9.2.5. Plastids 6.9.2.5.1. Chloroplasts 6.9.2.6. Ribosomes 6.9.2.7. Centrosome 6.9.2.8. Cilia and flagella 6.10. Cell motility 6.11. The cell nucleus 6.11.1. Characteristics of the cell nucleus 6.11.2. The interphase nucleus 6.11.3. The mitotic nucleus or nucleus in division 6.12. Bibliography 7. Metabolism 7.1. Metabolism 7.1.1. Energetic Aspects of Cellular Chemical Reactions 7.2. Catabolism 7.2.1. Catabolism and obtaining energy 7.2.2. Carbohydrate catabolism 7.2.2.1. Glycolysis 7.2.2.2. Cellular respiration 7.2.2.2.1. Oxidative decarboxylation 7.2.2.2.2. Krebs cycle 7.2.2.2.3. Electron transport chain 7.2.2.2.4. Energy balance of cellular respiration 7.2.2.3. Fermentations 7.2.2.3.1. Alcoholic or ethyl fermentation 7.2.2.3.2. Lactic fermentation 7.2.2.3.3. Other types of fermentations 7.3. Anabolism 7.3.1. Autotrophic anabolism 7.3.2. Photosynthesis 7.3.2.1. Photochemical or light phase 7.3.2.1.1. Photosystems 7.3.2.1.2. Photophosphorylation 7.3.2.1.2.1. Non cyclic photophosphorylation 7.3.2.1.2.2. Cyclic photophosphorylation 7.3.2.2. Biosynthetic or dark phase 7.3.2.3. Factors influencing photosynthesis 7.3.2.4. Products of photosynthesis 7.3.3. Chemosynthesis 7.4. Bibliography 8. Cell reproduction 8.1. The cell cycle 8.1.1. Interphase 8.1.2. Cellular division 8.2. Cellular division 8.2.1. Mitosis 8.2.1.1. Prophase 8.2.1.2. Metaphase 8.2.1.3. Anaphase 8.2.1.4. Telophase 8.2.1.5. Cytokinesis 8.2.1.6. More on mitosis 8.2.2. Meiosis 8.2.2.1. Meiosis I 8.2.2.2. Meiosis II 8.2.3. Meiosis and sexual reproduction 8.2.4. Meiosis and life cycle 8.2.5. Biological importance of meiosis 8.3. Differences and similarities between mitosis and meiosis 8.4. Bibliography 9. Classical genetics 9.1. Genetics basics 9.2. Mendelian genetics 9.2.1. The method 9.2.2. Mendel's Laws 9.2.2.1. Mendel's first law or principle of uniformity in the first generation 9.2.2.2. Mendel's second law or principle of segregation 9.2.2.2.1. Backcross and test crossover 9.2.2.3. Mendel's third law or principle of independent combination 9.3. Gene interaction 9.3.1. Gene interaction between allelic genes 9.3.2. Gene interaction between non-allelic genes that influence for the same trait 9.4. Chromosomal theory of heredity 9.5. Ligation and recombination 9.6. Complex mendelism 9.6.1. Multiple allelism 9.6.1.1. Lethal genes 9.6.2. Pleiotropy 9.6.3. Expressiveness and genetic penetrance 9.7. Sex-linked inheritance 9.7.1. Y-linked inheritance 9.7.2. X-linked inheritance 9.8. Heredity influenced by sex 9.9. Bibliography 10. Molecular genetics 10.1. DNA as hereditary material 10.2. DNA replication 10.2.1. The need for DNA replication 10.2.2. First hypotheses about DNA duplication 10.2.3. Meselson and Stahl experiment 10.2.4. The sense of growth of the new strands 10.2.5. Mechanism of DNA replication 10.2.5.1. Replication in prokaryotes 10.2.5.2. Replication in eukaryotes 10.2.6. Error correction 10.2.7. Enzymes involved in replication 10.3. Gene concept 10.4. "One gene-one enzyme" theory 10.5. Transcription 10.5.1. Mechanism of transcription 10.5.1.1. Transcription in prokaryotes 10.5.1.2. Eukaryotic transcription 10.6. Translation or protein biosynthesis 10.6.1. The genetic code 10.6.2. Mechanism of translation of RNA to proteins 10.6.2.1. Translation in eukaryotes 10.7. Regulation of gene expression 10.8. Bibliography 11. Genetics and evolution 11.1. Mutations 11.2. Types of mutations 11.2.1. Gene or point mutation 11.2.2. Chromosomal or structural mutation 11.2.3. Mutation at the genomic level 11.3. Causes of mutations 11.4. Evolutionary implications of mutations 11.5. Metabolic implications of mutations 11.6. Bibliography 12. Microbiology and biotechnology 12.1. Microbiology 12.2. Viruses 12.2.1. Viral morphology 12.2.2. Viral physiology 12.2.2.1. Lytic cycle 12.2.2.2. Lysogenic cycle 12.2.2.3. Cycles of viruses of special interest 12.2.2.3.1. Flu virus life cycle 12.2.2.3.2. Life cycle of the AIDS virus 12.3. Other acellular forms 12.3.1. Viroids 12.3.2. Prions 12.4. Biotechnology 12.5. Bibliography 13. Immunology 13.1. Infection concept 13.2. Defense mechanisms against infections 13.2.1. Nonspecific mechanisms 13.2.1.1. Primary barriers: external defenses 13.2.1.2. Secondary barriers: internal defenses 13.2.2. Specific mechanisms 13.3. Immunity and immune system 13.3.1. Components of the immune system 13.3.2. Concept and nature of antigens 13.4. The immune response 13.4.1. Humoral immune response: the antibodies 13.4.1.1. Antibody-producing cells: B lymphocytes 13.4.1.2. Antibodies 13.4.1.2.1. Types of antibodies 13.4.1.2.2. Antigen-antibody reaction 13.4.1.3. Immune memory: primary and secondary responses 13.4.2. Cellular immune response: T lymphocytes 13.5. Types of immunity 13.5.1. Natural immunity 13.5.2. Artificial immunity 13.6. Immune system disorders 13.6.1. Autoimmunity 13.6.2. Hypersensitivity 13.6.3. Immunodeficiency 13.6.4. Transplants and the phenomenon of rejections 13.7. Bibliography « Previous \| Next » 1.2.1. Primary bioelements Primary bioelements If the chemical composition of living matter (biosphere) is compared with that of the atmosphere, hydrosphere and lithosphere, which are the three layers that living beings occupy, the following conclusions can be drawn: In the biosphere we will find a high amount of H and O because living matter is made up of water in a percentage that varies between 65% (terrestrial organisms) to 90% (aquatic organisms). All chemical reactions that take place in living beings develop in water, so the existence of living matter without water is not possible. All of this indicates that life originated in water. The rest of the primary bioelements (C, N, S and P) of the biosphere are not so abundant in the atmosphere, hydrosphere or lithosphere, so it can be deduced that living matter has not been formed from the most common elements. abundant, but from those (C, H, O, N, P and S) that thanks to their properties are capable of constituting it. These properties are: Their atomic mass is relatively small, which favors the establishment of stable covalent bonds when combined. The smaller an atom, the greater the tendency of the positive nucleus to complete its last orbital with the electrons that form the bonds, and, therefore, the more stable these bonds are. Oxygen and nitrogen are highly electronegative elements, so when they join covalently with other atoms, they often give rise to dipole molecules. As water is also dipolar, these compounds dissolve well in it and can react with each other, making possible the biochemical processes essential for life. The rest of the properties are not common, so they are discussed separately below. Carbon. Hydrogen. Oxygen. Nitrogen. Sulfur. Phosphorous. Carbon It is the basic skeleton of all organic biomolecules and makes the difference between organic and inorganic matter. It has four electrons in its outermost shell and can form covalent bonds with other carbons, which allow it to form long chains of atoms (macromolecules). These bonds can be single (C-C), double (C=C) or triple (C≡C). It can also bind to the different radicals formed by the other elements (-H, = O, -OH, -NH₂, -SH, -H₂PO₄, etc.), thus allowing a large number of different molecules, that will intervene in a multitude of chemical reactions, and, thus, be able to take advantage of the great diversity of elements that exist in the environment. By Andreza Memelli (Own work) [Public domain], via Wikimedia Commons The four covalent bonds form, in space, the vertices of an imaginary tetrahedron, allowing the formation of three-dimensional structures, such as the plasma membrane or other organelles. The carbon also allows other macromolecule, the DNA, can contain all the information necessary to produce other molecules of the body and replicate to transmit that information to their descendants, being essential for life. Biological song: The carbon cycle (The frustrating journey of a carbon atom). Julinky. Hydrogen Together with oxygen, it is essential to form organic matter, which is defined as the matter basically made up of carbon and hydrogen. For example, some lipids are only made up of carbon and hydrogen atoms. The same as oil and its derivatives (butane, gasoline, diesel, etc.), consisting only of carbon and hydrogen, which is why they are called hydrocarbons. The electron in the hydrogen atom allows it to bind to any of the other primary bioelements. The covalent bonds that forms between hydrogen and carbon is strong enough to be stable, but not strong enough to prevent it from breaking, thus allowing the synthesis of other molecules. Molecules made up of only carbon and hydrogen are nonpolar covalents (insoluble in water). Oxygen It is the most electronegative primary bioelement, so when it binds with hydrogen, it attracts its only electron, originating electrical poles. Therefore, the radicals -OH, -CHO and -COOH are polar radicals. When these radicals replace some hydrogens of a chain of carbons and hydrogens, such as glucose (C₆H₁₂O₆), they originate soluble molecules in polar liquids such as water. Due to its electronegativity, oxygen has a great capacity to attract electrons from other atoms, leaving them oxidized. As this process involves the breaking of bonds and the release of a large amount of energy, the reaction of carbon compounds with oxygen, called aerobic respiration, is the most common way to obtain energy. The other route, fermentation, has been declining since algae and plants, through photosynthesis, began to enrich the primitive atmosphere with oxygen. The oxidation of biological compounds is basically carried out by subtracting hydrogens from carbon atoms. Oxygen (more electronegative) attracts the electron from hydrogen more strongly than carbon, so it is able to remove it. Thus water is formed (oxygen plus hydrogen) and a large amount of energy is released, which living beings take advantage of. As the carbon atom goes from sharing an electron with hydrogen, to sharing fewer electrons with oxygen, it experiences a "loss" of electrons, that is, it oxidizes: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy Nitrogen The nitrogen has a great facility for forming compounds with both hydrogen (NH₃) as with oxygen (NO^-), allowing, to the switch from one form to another, the release of energy. It is found in amino acids (molecules that make up proteins) forming amino groups (-NH₂) and in the nitrogenous bases of nucleic acids. Although nitrogen is the most abundant gas in the atmosphere, very few organisms are able to take advantage of it. Virtually all nitrogen is incorporated into living matter by algae and plants, which absorb it dissolved in the form of nitrate ion (NH₃^-). Sulfur It is found in the form of the sulfhydryl radical (-SH) in certain amino acids such as cysteine and methionine. These radicals make it possible to establish, between two nearby amino acids, strong covalent bonds called disulfide bridges (-SS-), which maintain the protein structure. Phosphorus It is very important because it forms energy-rich bonds. By breaking the bond that joins two phosphate groups -PO₃^- ~ PO₃^- ~ PO₃^2-, generally of a molecule called ATP (adenosine triphosphate), the energy contained in said bond is released. The energy released in other reactions, such as oxidations of respiration, is stored in these bonds. In addition, phosphorus is very important because it is part of the nucleic acids (DNA and RNA), of the *phospholipids* of the plasma membrane and of the bones of vertebrates, and because it helps to keep the acidity of the internal environment of the body constant. Licensed under the Creative Commons Attribution Share Alike License 4.0 « Previous \| Next » These pages are semi-automatically translated from the web Biology 2nd Baccalaureate. 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