6.9.2.8. Cilia and flagella

Cilia and flagella

The undulipodia (cilia and flagella) are mobile extensions of the plasma membrane of certain cells, consisting of microtubules.

The flagella have the function of allowing the movement of the cell, and the cilia, creating turbulence near the cell to bring food closer together.

The cilia are short and very numerous, covering the cell surface. Its movement is coordinated from back to front.
The flagella are long and few, generally only 1 or 2. Their movement is wave-like.

Although prokaryotic cells can possess flagella, their structure is totally different.

Structure and composition of cilia and flagella

Cilia and flagella are made up of:

The stem or axoneme. Surrounded by the plasma membrane and has inside:
- Two central microtubules surrounded by a thin nexin sheath .
- 9 pairs (doublets) of peripheral microtubules surrounding the central pair. In each pair, it is distinguished:
  - Microtubule A: complete, with 13 protofilaments. From this microtubule, two arms of the protein dynein emerge towards the microtubule B of the neighboring pair.
  - Microtubule B: with 10 protofilaments, it shares 3 with A.

This arrangement is called 9 + 2. The microtubule pairs are linked by nexin. Other nexin fibers link each A microtubule to the central sheath.

Transition zone. It is the area where the change occurs between the structure (9 + 2) of the stem or axoneme with the structure (9 + 0) of the basal body or centriole. The two central microtubules disappear, and the peripheral doublets become triplets.
The basal corpuscle is a cylinder located at the base of the cilium or flagellum, below the plasma membrane. It has the same structure as the centrioles (9 + 0), since it lacks the central microtubule pair, and has 9 peripheral microtubule triplets.
Ciliary roots (not always present). They are microfilaments that emerge from the lower end of the basal corpuscle, with a contractile function, which coordinates the movement of the cilia.

By LadyofHats. Versión en español de Alejandro Porto (File:Eukaryotic cilium diagram en.svg) [Public domain], via Wikimedia Commons

Function of cilia and flagella

The cilia perform two distinct functions:

Move the fluid or particles located on the surface of the cilia, such as the cells of the fallopian tube and the ciliated epithelial cells of the trachea and bronchi.
Propel the cell through a liquid, as in the case of some protozoa.

The cilia have a pendulum motion. The cilium, initially rigid, beats vigorously and then recovers until it returns to the initial position, in the same way as a field of wheat would be beaten by the wind.

The flagella are responsible for the displacement of various types of protozoa and sperm through an undulating movement. A wave is produced at the base that propagates to the other end of the flagellum.

As in muscle contraction, the movement of cilia and flagella is due to the sliding of some peripheral doublets with respect to others. As the doublets are anchored in the basal corpuscle, sliding causes flexion of the cilium. The dynein allows the gliding of the microtubules.

Video: The life of the ciliates.

Video: Sperm in motion seen with a light microscope.

Cilia and cells of the trachea

The main structures of the cells of the trachea are the cilia, since they are responsible for moving the mucus that retains the dust particles and other substances that arrive with the air that enters the lungs.

Fundamental ideas about cilia and flagella

Cilia and flagella

They are mobile extensions of the plasma membrane of some cells, made up of microtubules.
The cilia:
- They are short and very numerous, covering the cell surface.
- Pendulum movement, from back to front.
- They move the liquid nearby or are propelled through it.
Fhe flagella
- They are long and scarce, generally only 1 or 2.
- Movement is wave.
Structure of cilia and flagella:
- The stem or axoneme. Layout 9 + 2
- Two central microtubules.
- 9 pairs (doublets) of peripheral microtubules.
Transition zone.
The basal corpuscle. It has the same structure as the centrioles (9 + 0), since it lacks the central microtubule pair.
Ciliary roots (not always present).

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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 » 6.9.2.8. Cilia and flagella Cilia and flagella The undulipodia (cilia and flagella) are mobile extensions of the plasma membrane of certain cells, consisting of microtubules. The flagella have the function of allowing the movement of the cell, and the cilia, creating turbulence near the cell to bring food closer together. The cilia are short and very numerous, covering the cell surface. Its movement is coordinated from back to front. The flagella are long and few, generally only 1 or 2. Their movement is wave-like. Although prokaryotic cells can possess flagella, their structure is totally different. Structure and composition of cilia and flagella Cilia and flagella are made up of: The stem or axoneme. Surrounded by the plasma membrane and has inside: Two central microtubules surrounded by a thin nexin sheath . 9 pairs (doublets) of peripheral microtubules surrounding the central pair. In each pair, it is distinguished: Microtubule A: complete, with 13 protofilaments. From this microtubule, two arms of the protein *dynein* emerge towards the microtubule B of the neighboring pair. Microtubule B: with 10 protofilaments, it shares 3 with A. This arrangement is called 9 + 2. The microtubule pairs are linked by nexin. Other nexin fibers link each A microtubule to the central sheath. Transition zone. It is the area where the change occurs between the structure (9 + 2) of the stem or axoneme with the structure (9 + 0) of the basal body or centriole. The two central microtubules disappear, and the peripheral doublets become triplets. The basal corpuscle is a cylinder located at the base of the cilium or flagellum, below the plasma membrane. It has the same structure as the centrioles (9 + 0), since it lacks the central microtubule pair, and has 9 peripheral microtubule triplets. Ciliary roots (not always present). They are microfilaments that emerge from the lower end of the basal corpuscle, with a contractile function, which coordinates the movement of the cilia. By LadyofHats. Versión en español de Alejandro Porto (File:Eukaryotic cilium diagram en.svg) [Public domain], via Wikimedia Commons Function of cilia and flagella The cilia perform two distinct functions: Move the fluid or particles located on the surface of the cilia, such as the cells of the fallopian tube and the ciliated epithelial cells of the trachea and bronchi. Propel the cell through a liquid, as in the case of some protozoa. The *cilia* have a pendulum motion. The cilium, initially rigid, beats vigorously and then recovers until it returns to the initial position, in the same way as a field of wheat would be beaten by the wind. The flagella are responsible for the displacement of various types of protozoa and sperm through an undulating movement. A wave is produced at the base that propagates to the other end of the flagellum. As in muscle contraction, the movement of cilia and flagella is due to the sliding of some peripheral doublets with respect to others. As the doublets are anchored in the basal corpuscle, sliding causes flexion of the cilium. The dynein allows the gliding of the microtubules. Video: The life of the ciliates. Video: Sperm in motion seen with a light microscope. Cilia and cells of the trachea The main structures of the cells of the trachea are the cilia, since they are responsible for moving the mucus that retains the dust particles and other substances that arrive with the air that enters the lungs. Fundamental ideas about cilia and flagella Cilia and flagella They are mobile extensions of the plasma membrane of some cells, made up of microtubules. The cilia: They are short and very numerous, covering the cell surface. Pendulum movement, from back to front. They move the liquid nearby or are propelled through it. Fhe flagella They are long and scarce, generally only 1 or 2. Movement is wave. Structure of cilia and flagella: The stem or axoneme. Layout 9 + 2 Two central microtubules. 9 pairs (doublets) of peripheral microtubules. Transition zone. The basal corpuscle. It has the same structure as the centrioles (9 + 0), since it lacks the central microtubule pair. Ciliary roots (not always present). 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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Cilia and flagella

Structure and composition of cilia and flagella

Function of cilia and flagella