Lecture 12 Key Terms - The Cytoskeleton

12. The Cytoskeleton: Structure and Dynamics Introduc on The cytoskeleton is a dynamic network of protein filaments and tubules that offers structural help, shapes the cellular, and allows numerous cell capabili es, which includes movement, division, and intracellular transport. It is composed of 3 important varie es of filaments: microfilaments, intermediate filaments, and microtubules, every with dis nct residences and features. Components of the Cytoskeleton The cytoskeleton includes three primary varie es of protein filaments: • Microfilaments (Ac n Filaments): o Microfilaments are the thinnest filaments of the cytoskeleton, with a diameter of approximately 7 nm. They are composed of ac n, a globular protein that polymerizes to form long, helical filaments. O Microfilaments are extraordinarily dynamic, constantly undergoing polymeriza on and depolymeriza on, which permits the mobile to alternate shape and move. O Func ons of microfilaments encompass:  Cell Shape: Microfilaments make contribu ons to the cellular's form via forming a dense network below the plasma membrane, called the cor cal ac n network.  Cell Movement: Microfilaments are worried in mobile mo lity, such as strategies inclusive of amoeboid movement, cellular crawling, and muscle contrac on.  Cytokinesis: During cell division, microfilaments shape the contrac le ring that pinches the cellular in throughout cytokinesis. • Intermediate Filaments: o Intermediate filaments have a diameter of about 10 nm and provide mechanical electricity to cells. They are composed of various proteins, along with kera ns, vimen n, and lamins, relying on the mobile kind. O Intermediate filaments are more strong than microfilaments and microtubules, providing structural support and preserving the integrity of the cellular. O Func ons of intermediate filaments consist of:  Cell Structure: Intermediate filaments form a network that helps the cell's shape and anchors organelles in area.  Tissue Integrity: In epithelial cells, kera n intermediate filaments offer strength and resilience to ssues, suppor ng them withstand mechanical stress.  Nuclear Lamina: Lamins, a type of intermediate filament, shape the nuclear lamina, a meshwork that supports the nuclear envelope and organizes chroma n. • Microtubules: o Microtubules are the thickest filaments of the cytoskeleton, with a diameter of approximately 25 nm. They are composed of tubulin, a globular protein that polymerizes to shape hole tubes. O Microtubules are dynamic systems that may swi ly grow and reduce by including or ge ng rid of tubulin subunits. O Func ons of microtubules consist of:  Intracellular Transport: Microtubules serve as tracks for the movement of organelles, vesicles, and other mobile addi ves, driven via motor proteins which includes kinesins and dyneins.  Cell Division: During mitosis, microtubules form the mito c spindle, which separates chromosomes into daughter cells.  Cell Shape and Polarity: Microtubules assist maintain cellular shape and polarity, in par cular in polarized cells like neurons, wherein they guide the increase of axons and dendrites. Func ons of the Cytoskeleton The cytoskeleton is involved in a huge range of mobile methods: • Cell Shape and Mechanical Support: o The cytoskeleton gives structural assist to the cellular, suppor ng it maintain its shape and withstand mechanical stress. The interplay between microfilaments, intermediate filaments, and microtubules determines the general architecture of the mobile. • Cell Mo lity: o The cytoskeleton is crucial for cell movement. Ac n microfilaments allow cells to crawl on surfaces, at the same me as microtubules guide the movement of cilia and flagella, which propel cells through fluids. • Intracellular Transport: o The cytoskeleton acts as a network of tracks for the directed delivery of organelles, vesicles, and other shipment in the mobile. Motor proteins, inclusive of kinesins and dyneins, pass along microtubules to move cargo to unique loca ons. • Cell Division: o The cytoskeleton plays a crucial posi on in mobile division. During mitosis, microtubules form the mito c spindle, which segregates chromosomes into daughter cells. Microfilaments shape the contrac le ring that divides the cytoplasm during cytokinesis. • Signal Transduc on:  The cytoskeleton is involved in signal transduc on, in which it transmits mechanical indicators from the cellular surface to the interior, influencing cell behavior and gene expression. • Cell Polarity and Organiza on: o The cytoskeleton enables establish and keep mobile polarity, that is cri cal for procedures inclusive of uneven cellular division, ssue agency, and the forma on of specialized mobile systems like axons and dendrites. Cytoskeleton in Disease Dysfunc on of the cytoskeleton can lead to quite a few illnesses and problems: • Cancer: o Abnormali es in cytoskeletal proteins and their regula on can make a contribu on to cancer development. For instance, muta ons in tubulin or motor proteins can result in faulty mitosis, resul ng in aneuploidy and tumor development. • Neurodegenera ve Diseases: o Cytoskeletal defects are implicated in neurodegenera ve illnesses consis ng of Alzheimer's disorder, where odd tau protein forms tangles that disrupt microtubule func on and contribute to neuronal dying. • Muscular Dystrophies: o Muta ons in genes encoding cytoskeletal proteins, along with dystrophin, cause muscular dystrophies, a collec on of problems characterised through muscle weak spot and degenera on. • Ciliary Dyskinesia: o Defects in the structure or feature of cilia, which can be composed of microtubules, bring about primary ciliary dyskinesia (PCD), a condi on characterized with the aid of con nual respiratory infec ons, infer lity, and different signs.