Cell Organisation and Movement Flashcards
(16 cards)
What is the cytoskeleton?
A dynamic internal skeleton in eukaryotic cells that facilitates movement, shape, division, organelle organization, and intracellular transport.
What are the tree major filament systems in cytoskeleton?
1 Microfilaments (Actin)
2 Microtubules (Tubulin)
3 Intermediate Filaments (Keratin, Lamin)
Is the cytoskeleton static?
No! It is constantly remodeled and turned over by associated proteins.
What do actin filaments do?
They provide plasma membrane integrity, form surface structures (microvilli), serve as tracks for myosin motor proteins, and facilitate cell movement.
How does actin contribute to cell motility?
Actin filaments allow cells like fibroblasts and keratinocytes to crawl.
How does the actin cytoskeleton relate to cancer?
Changes in actin regulation can allow non-motile cells to move, leading to cancer metastasis.
What functions do microtubules serve?
They provide structural support for cilia/flagella, organize intracellular transport, and form the mitotic spindle for chromosome separation.
What molecular motors use microtubules?
Kinesins and Dyneins, powered by ATP hydrolysis.
How do drugs affect microtubules?
Colchicine (from meadow saffron) blocks microtubule polymerization, reducing inflammation in gout.
Taxol (from Pacific Yew) stabilizes microtubules, preventing cancer cell division.
What are the functions of intermediate filaments?
Provide structural integrity to the nucleus, skin, hair, nails.
Maintain tissue strength in epithelial cells.
Help cells resist mechanical stress.
What diseases are linked to intermediate filament defects?
Epidermolysis bullosa – Causes fragile skin & blistering due to keratin dysfunction.
Emery-Dreifuss Muscular Dystrophy & Cardiomyopathy – Caused by Lamin mutations affecting nuclear stability.
Hutchinson-Guilford Progeria – Premature aging disorder linked to Lamin A mutations.
How do different cells move?
Flagellates (Chlamydomonas) & Ciliates (Tetrahymena) → Use external appendages.
Amoebas & Human Macrophages → Reshape their cytoskeleton to move.
Neurons → Extend long processes selectively to specific targets.
How do bacteria hijack the cytoskeleton?
Listeria bacteria use actin polymerization to propel themselves inside host cells.
How do neutrophils track bacteria?
They follow chemical signals (chemotaxis) using cytoskeletal remodelling.
How do lymphocytes find tissue damage?
They detect molecular signals from wounded cells and crawl towards the injury site using cytoskeletal dynamics.
What happens when cytoskeletal regulation is disrupted?
It leads to diseases such as:
Cancer – Uncontrolled motility due to cytoskeletal changes.
Muscular dystrophy – Weakness due to faulty Lamin regulation.
Neurodegeneration – Cytoskeletal dysfunction affecting neuron structure.
Heart disease – Defective intermediate filaments affecting cardiac cells.
