Cell Cytoskeleton
Types:
- Dynamic Cytoskeleton
- Microtubule
- Microfilament
- Static Cytoskeleton
- Intermediate filament
Size
- Microtubulin > Intermediate filament > Microfilament
1. Microtubule
- Dynamic
- Structure:Â
- Diameter:Â 25 nanometre (Largest)
- Hollow cylindrical structure.
- ↳ Alpha and Beta tubulin subunits.
Dynamics | Length |
Plus end | ↑↑ by polymerization of tubulin |
Minus end | ↓↓ by depolymerization at non-growing end |
- GTP supplied by Magnesium triphosphate
- Functions
- Movement, cell division, Cilia, flagella, mitotic spindle
- centriole, axoplamic transport in neurons
Cilia
- Function:Â Motility.
Epithelium | Found in |
Simple ciliated columnar Epithelium | • Eustachian tube. • Middle ear. • Ventricles of brain. • Fallopian tube. |
Pseudostratified Ciliated Columnar Epithelium | • Respiratory epithilium • Membraneous Urethra • Spongy Urethra |
2. Microfilament
- Dynamic
- Diameter:Â 7 nanometer.
- Composed ofÂ
- G actin (globular actin)Â subunits.
- polymerize to form F actin (filamentous actin).
- Essentially:Â
- Actin (F-actin).
- Muscle contraction
- Microvilli
- Listeria motility
Microvilli
- Function: ↑↑ surface area.
- Seen in:
- Small intestine → for Absorption
- Gallbladder → for Storage
Action of Listeria
- Uses Internalins (A/B)Â
- Enters into cell
- Engulfed into vacuole
- (To contain its spread)
- Release Listeriolysin-O (LLO)
- Breakdown vacuole
- Act-A → Actin polymerization
- Comet tail pattern / Rocket tails
- (Polymerized actin)
- Tumbling motility / Jet actin motility
- Infect nearby cells
Intermediate Filament
- Static
- Length does not change with cell growth/loss.
Intermediate Filament | Function | Tumor markers |
Cytokeratin | Carcinomas - Epithelial cells. | SCC Mallory Denk bodies |
Vimentin | Mesencymal tumors | ã…¤ |
Desmin | Muscles | Rhabdomyosarcoma |
GFAP | Neuronal | ã…¤ |
DO NOT CONFUSE LAMIN AND LAMININ
Lamin
- Aka nuclear lamin → intermediate filament
- Disorder of premature ageing (Hutchinson Gilford)
- Functions
- Disassembly and reformation of the nuclear envelope during mitosis
- positioning of nuclear pores and apoptosis.
Laminin
- Extracellular glycoprotein
- Mnemonic: if 2 in present → big protein - glycoprotein
- highest concentration in basement membranes
- Functions
- cell adhesion, migration, and signalling
- Cystic BRAIN TUMORS
- Craniopharyngioma
- JPA
Marker | Positive In | Mnemonic / Note |
Cytokeratin (CK) | Carcinoma | C for C |
Vimentin | Sarcoma | ã…¤ |
CD45 / LCA Leucocyte Common Antigen | Lymphoma | L for L |
HMB45 S 100 | Melanoma | M for M |
CD1A | Langerhans Cell Histiocytosis (LCH) | ã…¤ |
CD99 | Granulosa Cell Tumor (ovary) | 99-year-old granny |
(MIC2) | Ewing Sarcoma (bone) | Mitu → childhood tumor |
Glial Fibrillary Acidic Protein (GFAP) | Tumor markers in glioma (Astrocytoma, Glioblastoma multiforme) | ㅤ |
Lamin | Progeria: Disorder of premature ageing (Hutchinson Gilford) | ã…¤ |
- Mnemonic:
- Sarcoma
- Vimal Sar
- Also remember Rape (Rhabdomyosarcoma) Syn (Synovial) Mnemonic
- Car
- Sit (Cytokeratin) inside Car
- Remember car → bike → took another route
- Helmet (HCC → Fibrolamellar)
- Rc book (RCC)
- Phone (Follicular CA)
- Granulosa cell tumor mnemonic
- 99 year old granny ex ne vilikkan poi.
- (99 (CD 99) year old granny → hyper estrogenism () → Called Ex (Call exner) → offered coffee (coffee bean) → she shouldve inhibited (inhibin) her)
- Ewings sarcoma Mnemonic:
- Mittu (MIC2) (11 year old) → Onion () kazhichapo wings () vannu → to Wings to Fly (EWS-FLI1) in Right (Homer wright) direction to get Pasta (Pas +ve).
- Mittu thirichu vannapo 22 vayassai (t(11:22))
Condition | Feature |
NF1 | Chromosome 17 |
NF2 | Chromosome 22 |
DermatoFIBROSARCOMA protrubans | t (17;22) |
Nodular Fascitis | t (22;17) |
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