6.9.2.4. Mitochondria

Mitochondria

The mitochondria are present in almost all eukaryotic cells, whereas chloroplasts appear only in photosynthetic plant cells. Both are included within the energetic organelles of cells.

If it weren't for the mitochondria, heterotrophic cells could only obtain their ATP from anaerobic glycolysis, but with them they can completely degrade glucose in the presence of oxygen to convert it into carbon dioxide and water, obtaining much more energy.

The number of mitochondria depends on the energy needs of the cell, being located in areas where a significant consumption of ATP is required.

The chondriome is the set of all the mitochondria in a cell.

Structure of the mitochondria

The mitochondria are cylindrical and are bounded by a double membrane, the outer mitochondrial membrane, which separates the hialoplasma, and the inner mitochondrial membrane, having a folds inward increasing its surface, the mitochondrial cristae. These membranes leave two compartments: the intermembrane space, between both membranes, and the mitochondrial matrix, the space that surrounds the inner mitochondrial membrane.

Por Aibdescalzo [Public domain], undefined

Chemical composition of mitochondria

The mitochondrial matrix

Limited by the inner mitochondrial membrane, in addition to 50% water, the content of the matrix includes:

DNA molecules (mitochondrial-DNA), double-stranded and circular (such as bacteria and chloroplasts), which contain information to synthesize mitochondrial proteins. This DNA is different from nuclear DNA.
Mitochondrial RNA molecules forming the mitorribosomes, different from the rest of the ribosomes of the cell.
Ribosomes (the mitorribosomes), which can be both free and attached to the inner mitochondrial membrane. They are similar to bacterial ribosomes (70 S), smaller than cytoplasmic ribosomes.
Calcium and phosphate ions, ADP, ATP, coenzyme-A, etc.
Enzymes necessary for the replication, transcription and translation of mitochondrial DNA to synthesize mitochondrial proteins.
Enzymes necessary to develop the Krebs cycle and the β-oxidation of fatty acids.

The inner mitochondrial membrane

The inner mitochondrial membrane has a large surface area because it has folds called mitochondrial ridges, where enzymes of the respiratory chain and mitochondrial ATPase are located.

It is impermeable to ions and other substances, which have to pass through it through transporter proteins.

It has more proteins (80%) than the other cell membranes and it has no cholesterol (as in bacteria) among its lipids (20%). Among the proteins, the following stand out:

The proteins that make up the respiratory chain that carry electrons to molecular oxygen.
An enzyme complex, mitochondrial ATP synthase, that catalyzes the synthesis of ATP (oxidative phosphorylation).
The carrier proteins, allowing the passage of ions and molecules between the mitochondrial matrix and cytosol.

The outer mitochondrial membrane

It is the membrane that surrounds the mitochondria, in contact with the cytosol. It has the same structure as the rest of cell membranes: a lipid double layer and associated proteins.

The outer mitochondrial membrane resembles other cell membranes, specifically those of the endoplasmic reticulum. Among its proteins we distinguish:

Proteins that form large water channels or porins and make it very permeable, unlike the inner mitochondrial membrane. These channels are not selective and allow large molecules to pass through.
Enzymes, such as those that activate fatty acids to be oxidized in the mitochondrial matrix.

The intermembrane space

Located between the outer and inner membranes, with a composition similar to that of the cytosol due to the permeability of the outer mitochondrial membrane, although it contains enzymes that allow it to transfer the energy from ATP obtained in the mitochondria to other nucleotides, for example, AMP.

Fundamental ideas about mitochondria

Mitochondria are energetic cellular organelles with an elongated shape, formed by a double membrane (outer mitochondrial membrane and inner mitochondrial membrane), an intermembrane space and a mitochondrial matrix.

The origin of mitochondria and chloroplasts is in some aerobic bacteria and other photosynthetic bacteria that were ingested by some prokaryotes and had a symbiotic relationship and evolved together. Therefore, mitochondria and chloroplasts are organelles similar to prokaryotic cells.

Thus, mitochondria and chloroplasts were formed, organelles very similar to prokaryotic cells, which gave rise to eukaryotic cells.

Mitochondrial matrix: Contains:
- double-stranded and circular DNA.
- Mitochondrial RNA molecules.
- Mitoribosomes. Ribosomes similar to bacterial ribosomes (70 S), smaller than cytoplasmic ribosomes .
- Calcium and phosphate ions, ADP, ATP, coenzyme-A, etc.
- Enzymes necessary for the replication, transcription, and translation of mitochondrial DNA to synthesize mitochondrial proteins.
- Enzymes necessary for the metabolic pathways that occur in the mitochondrial matrix:
  - Krebs cycle.
  - β-oxidation of fatty acids.
Inner mitochondrial membrane
- Mitochondrial cristae: folds where the enzymes of the respiratory chain and the mitochondrial ATPase (ATP synthesis) are.
- It has carrier proteins for ions and other substances to pass through.
- It has no cholesterol.
Outer mitochondrial membrane
- in contact with the cytosol.
- Proteins with large aqueous channels or porins that make it a very permeable membrane.
intermembrane space
- Between the outer and inner membranes.
- Composition similar to that of the cytosol by the permeability of the outer mitochondrial membrane.

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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 » 6.9.2.4. Mitochondria Mitochondria The mitochondria are present in almost all eukaryotic cells, whereas chloroplasts appear only in photosynthetic plant cells. Both are included within the energetic organelles of cells. If it weren't for the mitochondria, heterotrophic cells could only obtain their ATP from anaerobic glycolysis, but with them they can completely degrade glucose in the presence of oxygen to convert it into carbon dioxide and water, obtaining much more energy. The number of mitochondria depends on the energy needs of the cell, being located in areas where a significant consumption of ATP is required. The chondriome is the set of all the mitochondria in a cell. Structure of the mitochondria The mitochondria are cylindrical and are bounded by a double membrane, the outer mitochondrial membrane, which separates the hialoplasma, and the inner mitochondrial membrane, having a folds inward increasing its surface, the mitochondrial cristae. These membranes leave two compartments: the intermembrane space, between both membranes, and the mitochondrial matrix, the space that surrounds the inner mitochondrial membrane. Por Aibdescalzo [Public domain], undefined Chemical composition of mitochondria The mitochondrial matrix Limited by the inner mitochondrial membrane, in addition to 50% water, the content of the matrix includes: DNA molecules (mitochondrial-DNA), double-stranded and circular (such as bacteria and chloroplasts), which contain information to synthesize mitochondrial proteins. This DNA is different from nuclear DNA. Mitochondrial RNA molecules forming the mitorribosomes, different from the rest of the ribosomes of the cell. Ribosomes (the *mitorribosomes), which can be both free and attached to the inner mitochondrial membrane. They are similar to bacterial ribosomes (70 S), smaller than cytoplasmic ribosomes. Calcium and phosphate ions, ADP, ATP, coenzyme-A, etc. Enzymes necessary for the replication, transcription and translation of mitochondrial DNA to synthesize mitochondrial proteins. Enzymes necessary to develop the Krebs cycle* and the β-oxidation of fatty acids. The inner mitochondrial membrane The inner mitochondrial membrane has a large surface area because it has folds called mitochondrial ridges, where enzymes of the respiratory chain and mitochondrial ATPase are located. It is impermeable to ions and other substances, which have to pass through it through transporter proteins. It has more proteins (80%) than the other cell membranes and it has no cholesterol (as in bacteria) among its lipids (20%). Among the proteins, the following stand out: The proteins that make up the respiratory chain that carry electrons to molecular oxygen. An enzyme complex, mitochondrial ATP synthase, that catalyzes the synthesis of ATP (oxidative phosphorylation). The carrier proteins, allowing the passage of ions and molecules between the mitochondrial matrix and cytosol. The outer mitochondrial membrane It is the membrane that surrounds the mitochondria, in contact with the cytosol. It has the same structure as the rest of cell membranes: a lipid double layer and associated proteins. The outer mitochondrial membrane resembles other cell membranes, specifically those of the endoplasmic reticulum. Among its proteins we distinguish: Proteins that form large water channels or porins and make it very permeable, unlike the inner mitochondrial membrane. These channels are not selective and allow large molecules to pass through. Enzymes, such as those that activate fatty acids to be oxidized in the mitochondrial matrix. The intermembrane space Located between the outer and inner membranes, with a composition similar to that of the cytosol due to the permeability of the outer mitochondrial membrane, although it contains enzymes that allow it to transfer the energy from ATP obtained in the mitochondria to other nucleotides, for example, AMP. Fundamental ideas about mitochondria Mitochondria are energetic cellular organelles with an elongated shape, formed by a double membrane (outer mitochondrial membrane and inner mitochondrial membrane), an intermembrane space and a mitochondrial matrix. The origin of mitochondria and chloroplasts is in some aerobic bacteria and other photosynthetic bacteria that were ingested by some prokaryotes and had a symbiotic relationship and evolved together. Therefore, mitochondria and chloroplasts are organelles similar to prokaryotic cells. Thus, mitochondria and chloroplasts were formed, organelles very similar to prokaryotic cells, which gave rise to eukaryotic cells. Mitochondrial matrix: Contains: double-stranded and circular DNA. Mitochondrial RNA molecules. Mitoribosomes. Ribosomes similar to bacterial ribosomes (70 S), smaller than cytoplasmic ribosomes . Calcium and phosphate ions, ADP, ATP, coenzyme-A, etc. Enzymes necessary for the replication, transcription, and translation of mitochondrial DNA to synthesize mitochondrial proteins. Enzymes necessary for the metabolic pathways that occur in the mitochondrial matrix: Krebs cycle. β-oxidation of fatty acids. Inner mitochondrial membrane Mitochondrial cristae: folds where the enzymes of the *respiratory chain* and the *mitochondrial ATPase* (ATP synthesis) are. It has carrier proteins for ions and other substances to pass through. It has no cholesterol. Outer mitochondrial membrane in contact with the cytosol. Proteins with large aqueous channels or porins that make it a very permeable membrane. intermembrane space Between the outer and inner membranes. Composition similar to that of the cytosol by the permeability of the outer mitochondrial membrane. 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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