2.5. Disaccharides

Disaccharides

Disaccharides are formed by the union of two monosaccharides through an O-glucosidic bond, which can be done in two ways:

By monocarbonyl bond between the anomeric carbon of the first monosaccharide and any non-anomeric carbon of the second. As an anomeric carbon remains with the free hemiacetal, it continues to have the reducing capacity. For example, the maltose, the cellobiose and lactose. The name ending of the first monosaccharide is -osil and that of the second monosaccharide is -ose.

By Javier Velasco (Own work) [CC BY-SA 4.0], via Wikimedia Commons

By dicarbonyl bonding, when the two anomeric carbons of the two monosaccharides are involved, thereby losing the reducing capacity, such as sucrose. The name ending of the first monosaccharide is -osil and that of the second monosaccharide is -oside.

Disaccharides have the same properties as monosaccharides: they are soluble in water, crystallizable, colorless and sweet in taste. Its reducing capacity depends on whether it has a free anomeric group.

The main disaccharides of biological interest are:

Principales disacáridos

http://biogeo.iespedrojimenezmontoya.es/BIOLOGIAJM/BIOQUIMICA/TEMA3GLUCIDOS.htm, CC BY-SA 4.0, via Wikimedia Commons

Maltose

Disaccharide formed by two D-glucopyranose molecules linked by α (1 → 4) bond, between the oxygen of the first anomeric carbon (from -OH) of one glucose and the oxygen belonging to the fourth carbon of the other. The maltose is α-D-glucopyranosyl (1 → 4) -D-glucopyranose and having free the anomeric carbon of the second is a disaccharide reducer .

The maltose is also called malt sugar as it appears in the germinated barley grains.

Animation: Formation of a disaccharide (maltose).

Cellobiose

Disaccharide formed by two D-glucopyranose molecules linked by β bond (1 → 4). He is not free in nature. It is obtained by hydrolysis of cellulose.

Lactose

The lactose is a disaccharide formed by the union of a molecule D-galactopyranose and D-glucopyranose another joined by a β (1→4). It is found free in the milk of mammals.

Sucrose or saccharose

Disaccharide formed by a molecule of α-D-glucopyranose and another of β-D-fructofuranose linked by means of an α bond (1→2). The bond is made between the -OH of the anomeric carbon of the first monosaccharide and the -OH of the anomeric carbon of the second. Due to this dicarbonyl bond, it is the only disaccharide of those mentioned that does not have reducing power on Fehling's liquor.

It is found in sugar cane and sugar beet, it is the sugar of habitual consumption.

Conservation in syrup

As you know, it is common to preserve fruit in syrup, based on highly concentrated sucrose solutions. But sucrose is also a good substrate for many microorganisms that can break down that food.

The preservation of food in syrup is based on the fact that the high concentration of sucrose creates a hypertonic environment (high osmotic pressure) that prevents the development of microorganisms that can cause food spoilage.

Isomalt

Disaccharide formed by two D-glucopyranose molecules joined by α bond (1→6). He is not free in nature. It is obtained by hydrolysis of amylopectin (a component of starch and glycogen). It comes from the α branch points of these polysaccharides.

Isomaltosa By NEUROtiker (Own work) [Public domain], via Wikimedia Commons

Fundamental ideas about disaccharides

The disaccharides that you should know for the university entrance exam are:

Maltose: union of two glucoses with α bond (1→4). It is obtained by hydrolysis of starch and glycogen.
Cellobiose: union of two glucoses with β bond (1→4). It is obtained by hydrolysis of cellulose.
Lactose: binding of a galactose and a glucose with a β bond (1→4).
Saccharose o sucrose: union of a glucose and a fructose by α bond (1→2). It is the sugar that we use in food and in the images of university entrance exams that appear on these lines.

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1st ESO	3rd ESO	4th ESO	Biology 2nd Baccalaureate
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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 » 2.5. Disaccharides Disaccharides Disaccharides are formed by the union of two monosaccharides through an O-glucosidic bond, which can be done in two ways: By monocarbonyl bond between the anomeric carbon of the first monosaccharide and any non-anomeric carbon of the second. As an anomeric carbon remains with the free hemiacetal, it continues to have the reducing capacity. For example, the maltose, the cellobiose and lactose. The name ending of the first monosaccharide is -osil and that of the second monosaccharide is -ose. By Javier Velasco (Own work) [CC BY-SA 4.0], via Wikimedia Commons By dicarbonyl bonding, when the two anomeric carbons of the two monosaccharides are involved, thereby losing the reducing capacity, such as sucrose. The name ending of the first monosaccharide is -osil and that of the second monosaccharide is -oside. Disaccharides have the same properties as monosaccharides: they are soluble in water, crystallizable, colorless and sweet in taste. Its reducing capacity depends on whether it has a free anomeric group. The main disaccharides of biological interest are: Maltose. Cellobiose. Lactose. Saccharose o sucrose. Isomalt. http://biogeo.iespedrojimenezmontoya.es/BIOLOGIAJM/BIOQUIMICA/TEMA3GLUCIDOS.htm, CC BY-SA 4.0, via Wikimedia Commons Maltose Disaccharide formed by two D-glucopyranose molecules linked by α (1 → 4) bond, between the oxygen of the first anomeric carbon (from -OH) of one glucose and the oxygen belonging to the fourth carbon of the other. The maltose is α-D-glucopyranosyl (1 → 4) -D-glucopyranose and having free the anomeric carbon of the second is a disaccharide reducer . The maltose is also called malt sugar as it appears in the germinated barley grains. Animation: Formation of a disaccharide (maltose). Cellobiose Disaccharide formed by two D-glucopyranose molecules linked by β bond (1 → 4). He is not free in nature. It is obtained by hydrolysis of cellulose. Lactose The lactose is a disaccharide formed by the union of a molecule D-galactopyranose and D-glucopyranose another joined by a β (1→4). It is found free in the milk of mammals. Sucrose or saccharose Disaccharide formed by a molecule of α-D-glucopyranose and another of β-D-fructofuranose linked by means of an α bond (1→2). The bond is made between the -OH of the anomeric carbon of the first monosaccharide and the -OH of the anomeric carbon of the second. Due to this dicarbonyl bond, it is the only disaccharide of those mentioned that does not have reducing power on Fehling's liquor. It is found in sugar cane and sugar beet, it is the sugar of habitual consumption. Conservation in syrup As you know, it is common to preserve fruit in syrup, based on highly concentrated sucrose solutions. But sucrose is also a good substrate for many microorganisms that can break down that food. The preservation of food in syrup is based on the fact that the high concentration of sucrose creates a hypertonic environment (high osmotic pressure) that prevents the development of microorganisms that can cause food spoilage. Isomalt Disaccharide formed by two D-glucopyranose molecules joined by α bond (1→6). He is not free in nature. It is obtained by hydrolysis of amylopectin (a component of starch and glycogen). It comes from the α branch points of these polysaccharides. By NEUROtiker (Own work) [Public domain], via Wikimedia Commons Fundamental ideas about disaccharides The disaccharides that you should know for the university entrance exam are: Maltose: union of two glucoses with α bond (1→4). It is obtained by hydrolysis of starch and glycogen. Cellobiose: union of two glucoses with β bond (1→4). It is obtained by hydrolysis of cellulose. Lactose: binding of a galactose and a glucose with a β bond (1→4). Saccharose o sucrose: union of a glucose and a fructose by α bond (1→2). It is the sugar that we use in food and in the images of university entrance exams that appear on these lines. 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. Biología de 2º de Bachillerato (biologia-geologia.com). You can make any suggestion, question, comment, ..., in our forum 2º Bachillerato Biología - Foro de biologia-geologia.com
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