Cytoskeleton - Dr white Flashcards
What is treadmilling?
Is growing of plus end and shrinking of minus end
predomniates in Actin
How significant is the Cytoskeleton of an RBC?
- It provides the RBC its BICONCAVE shape
- Flexibility to manuever through tight capiliaries
- Strength to withstand heart contractions
- Defective RBC Cytoskeleton
- HEREDITARY SPHEROCYTOSIS
- RBC is SPHERICAL not biconcave
- Fragile = burst
- Hemolytic Anemia
- HEREDITARY SPHEROCYTOSIS
What is the basic organization of Cytoskeleton?
Multiple protofilaments
- Linear strings of protein subunits joned end to end
- thermodynamic unstable
- arranged one on top of another
- thermodynamic stable
What is dynamic instability?
occurs when there is a loss of the GTP cap causes seperationg of chromosomes
predominates in Microtubules
What are the characteristics of intermediate filaments
Functions :
- Provides mechanical strength
- strong filaments
- resists mechanicl stress
- allows formation of hair and fingernails
Formation of
- (alpha helical regions present in each monomer)
- monomer + monermer = parallelcoiled dimer
- Dimer + dimer = staggered = tetramer
- 8 tetramers = 1 protofilament laterally
What is the function of the cytoskeleton?
- Organization
- rearranges cellular componets
- directs intracellular traffic
- Maintains cell shape
- supports Internal structure and the PM
- Moves the cell
- ex: RBC, WBC “white blood cell”, fibroblasts, and sperm
- Mscle conrtaction
- provides mechanica strength (resistance to forces that rip cell apart)
- Pulls chromosomes apart
Whatare charcteristics of Actin monomers
compact and globular
Functions:
- shape of cell surface
- cell locomotion
- secreation
- endoscytosis
Actin subunits combine to form helical assembly = F actin (right hand helix)
- self assocatie
- polarity
- Plus :Fastgrowing/shrinking ATP bound
- Minus: slow growing /shrinking : ADP bound
- Flexable and easily bent
What are acessory proteins
essential for assembly of cytoskeletal filaments
motor proteins which are machines for converting energy of atp into mechanical movement
move organelles along filaments or filaments themselves
What are the charactersitics of Tubulin?
- Long hollow cylinders; diameter 25nm
- more rigid than actin
- attached to centrosome (microtuble organizer)
heterodimer
- alpha tubulin and beta tublin w/ non covalent bones both have 1 GTP binding sites
- Plus end = fast growing/fast shrinking
- minus: slow growing / slow shrinking
- Form micotubles w/ 13 protofilaments aligned parallel with alternating alpha and beta tublins
What are the 3 families of cytoskeleton proteins?
Actin monomers, microtubles, intermediate filaments
