6.9.2.1. Lysosomes

Lysosomes

The lysosomes are organelles globular, formed by the Golgi apparatus, present in both animal cells and plant.

Lysosomes are membranous vesicles, inside which intracellular digestion takes place. Its membrane is of the 75 Å unitary type, covered on the inside by a thick layer of glycoproteins that protect it from destruction by the action of hydrolase enzymes. The lysosome membrane contains a proton pump that introduces H⁺ and maintains the acidic pH, below 5, into the lysosome, and transport proteins that allow the products resulting from digestion to pass into the cytosol.

By Alejandro Porto (Own work) [CC BY-SA 3.0], via Wikimedia Commons

Chemical composition and types of lysosomes

The lysosomes containing about 50 different enzymes type acid hydrolases, synthesized in the rough endoplasmic reticulum. They are enzymes capable of digesting macromolecules and function optimally in a medium with a pH=5. The pH remains acidic thanks to the proton pumps of the lysosome membrane. They also have transport proteins that allow digested products to pass into the cytosol. The lysosome membrane contains highly glycosylated integral acid proteins, which protect it from the enzymes it contains.

Lysosomes contain a large number of hydrolytic enzymes, but their content can be very different. Two types of lysosomes are distinguished:

Primary lysosomes (also called "hydrolase vesicles"). They only contain hydrolytic enzymes. They are vesicles of secretion newly formed by budding from the cisternae of the Golgi apparatus. They can form secondary lysosomes or expel their contents to the outside.
Secondary lysosomes. They also contain hydrolases, but also substrates in the process of digestion . They are primary lysosomes fused with other substances, of internal or external origin. According to the substance they hydrolyze, two types are distinguished:
- Heterophagic vacuoles: fusion of a primary lysosome with particles that come from outside the cell (phagolysosome).
- Autophagic vacuoles: fusion of a primary lysosome with different parts of the cell that are no longer needed or damaged areas (autophagolysosome).

Functions of lysosomes

The lysosomes are responsible for the digestion of macromolecules, although in some cases, serve as temporary storage for reservations:

1.- Cell digestion. Lysosomes can digest macromolecules, both internal and external. This function is performed in two ways:

Autophagy. It matters that digests is a part of the cell, as fragments of the endoplasmic reticulum or Golgi apparatus cisterns. Autophagy is important for cells, as it destroys damaged areas, intervenes in cell development, and allows cell nutrition when conditions are unfavorable.
Heterophagy. What is digested has an external origin. It has the dual purpose of nurturing and defending the cell. The substrates enter the cell by endocytosis, forming a vesicle that fuses to a primary lysosome, originating a digestive vacuole, where digestion occurs. The products of digestion pass into the hyaloplasm, where they are reused. What cannot be digested, is expelled to the outside by exocytosis, being able to fuse with the plasma membrane.

2.- Storage of reserve substances. In seeds there is a special type of secondary lysosomes, aleurone grains, which store reserve substances. Cellular digestion does not occur until germination time. Hydrolytic enzymes are then activated, initiating intracellular digestion, the products of which will be used in the development of the embryo.

Lysosomes and white blood cells

White blood cells contain many lysosomes, as they contain the necessary enzymes to digest foreign substances that may enter the body.

Curiosity: Lysosomal Storage Diseases

A genetic lysosomal storage disease is Gaucher disease, produced by the mutation of the gene that encodes the enzyme responsible for the hydrolysis of glycolipids. The undigested material accumulates inside the lysosomes.

There are also other diseases related to lysosomes due to changes in their membranes that allow hydrolases to discharge into the hyaloplasm. For example, if the cells engulf substances capable of breaking the lysosome membrane, as happens in gout and silicosis.

The drop is a disease characterized by excessive production of uric acid, which causes the acid concentration in the plasma is so high that crystallizes in the synovial fluid of the joints. White blood cells engulf these crystals, but the formed vacuoles are broken and hydrolases are released that digest the white blood cell, reach the joints, and an inflammatory reaction, arthritis, occurs.

The silicosis is a typical disease caused by mining inhalation of silica particles. Silica reaches the lungs, where it is engulfed by cells whose vacuoles are destroyed. Muscle tissue defends itself by manufacturing collagen fibers, but this fibrosis prevents the transport of gases, thus rendering the lung tissue useless.

Fundamental Ideas About Lysosomes

The lysosomes:

They are globular organelles.
Formed by the Golgi apparatus.
They contain acidic hydrolase enzymes that are responsible for intracellular digestion.
Types of lysosomes:
- Primary lysosomes or vesicles with hydrolases.
- Secondary lysosomes: contain hydrolases and substrates in the process of digestion.
  - Heterophagic vacuoles.
  - Autophagic vacuoles.
Functions of lysosomes :
- Cell digestion.
- Storage of reserve substances.

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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 » 6.9.2.1. Lysosomes Lysosomes The lysosomes are organelles globular, formed by the Golgi apparatus, present in both animal cells and plant. Lysosomes are membranous vesicles, inside which intracellular digestion takes place. Its membrane is of the 75 Å unitary type, covered on the inside by a thick layer of glycoproteins that protect it from destruction by the action of hydrolase enzymes. The lysosome membrane contains a proton pump that introduces H⁺ and maintains the acidic pH, below 5, into the lysosome, and transport proteins that allow the products resulting from digestion to pass into the cytosol. By Alejandro Porto (Own work) [CC BY-SA 3.0], via Wikimedia Commons Chemical composition and types of lysosomes The lysosomes containing about 50 different enzymes type acid hydrolases, synthesized in the rough endoplasmic reticulum. They are enzymes capable of digesting macromolecules and function optimally in a medium with a pH=5. The pH remains acidic thanks to the proton pumps of the lysosome membrane. They also have transport proteins that allow digested products to pass into the cytosol. The lysosome membrane contains highly glycosylated integral acid proteins, which protect it from the enzymes it contains. Lysosomes contain a large number of hydrolytic enzymes, but their content can be very different. Two types of lysosomes are distinguished: Primary lysosomes (also called "hydrolase vesicles"). They only contain hydrolytic enzymes. They are vesicles of secretion newly formed by budding from the cisternae of the Golgi apparatus. They can form secondary lysosomes or expel their contents to the outside. Secondary lysosomes. They also contain hydrolases, but also substrates in the process of digestion . They are primary lysosomes fused with other substances, of internal or external origin. According to the substance they hydrolyze, two types are distinguished: *Heterophagic vacuoles: fusion of a primary lysosome with particles that come from outside the cell (phagolysosome). Autophagic vacuoles: fusion of a primary lysosome with different parts of the cell that are no longer needed or damaged areas (autophagolysosome). Functions of lysosomes The lysosomes* are responsible for the digestion of macromolecules, although in some cases, serve as temporary storage for reservations: 1.- Cell digestion. Lysosomes can digest macromolecules, both internal and external. This function is performed in two ways: Autophagy. It matters that digests is a part of the cell, as fragments of the endoplasmic reticulum or Golgi apparatus cisterns. Autophagy is important for cells, as it destroys damaged areas, intervenes in cell development, and allows cell nutrition when conditions are unfavorable. Heterophagy. What is digested has an external origin. It has the dual purpose of nurturing and defending the cell. The substrates enter the cell by endocytosis, forming a vesicle that fuses to a primary lysosome, originating a digestive vacuole, where digestion occurs. The products of digestion pass into the hyaloplasm, where they are reused. What cannot be digested, is expelled to the outside by exocytosis, being able to fuse with the plasma membrane. 2.- Storage of reserve substances. In seeds there is a special type of secondary lysosomes, aleurone grains, which store reserve substances. Cellular digestion does not occur until germination time. Hydrolytic enzymes are then activated, initiating intracellular digestion, the products of which will be used in the development of the embryo. Lysosomes and white blood cells White blood cells contain many lysosomes, as they contain the necessary enzymes to digest foreign substances that may enter the body. Curiosity: Lysosomal Storage Diseases A genetic lysosomal storage disease is Gaucher disease, produced by the mutation of the gene that encodes the enzyme responsible for the hydrolysis of glycolipids. The undigested material accumulates inside the lysosomes. There are also other diseases related to lysosomes due to changes in their membranes that allow hydrolases to discharge into the hyaloplasm. For example, if the cells engulf substances capable of breaking the lysosome membrane, as happens in gout and silicosis. The drop is a disease characterized by excessive production of uric acid, which causes the acid concentration in the plasma is so high that crystallizes in the synovial fluid of the joints. White blood cells engulf these crystals, but the formed vacuoles are broken and hydrolases are released that digest the white blood cell, reach the joints, and an inflammatory reaction, arthritis, occurs. The silicosis is a typical disease caused by mining inhalation of silica particles. Silica reaches the lungs, where it is engulfed by cells whose vacuoles are destroyed. Muscle tissue defends itself by manufacturing collagen fibers, but this fibrosis prevents the transport of gases, thus rendering the lung tissue useless. Fundamental Ideas About Lysosomes The lysosomes: They are globular organelles. Formed by the Golgi apparatus. They contain acidic hydrolase enzymes that are responsible for intracellular digestion. Types of lysosomes: Primary lysosomes or vesicles with hydrolases. Secondary lysosomes: contain hydrolases and substrates in the process of digestion. Heterophagic vacuoles. Autophagic vacuoles. Functions of lysosomes : Cell digestion. Storage of reserve substances. 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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Lysosomes

Chemical composition and types of lysosomes

Functions of lysosomes