Cytoskeleton Flashcards
What is the proximate cause of multicellular organisms cell shapes
Changes in internal organisation due to changes in cytoskeleton
What is the ultimate cause of multicellular organisms cell shapes
Difference in cell structure due to changes in gene expression
What is the role of actin filaments
Key in cell division, cell migration and cell contraction
What is the main role of microtubules
Main role to create mitotic spindles used in cell division and present in nerve cells
How are cytoskeleton polymers formed
Formed by non-covalent protein-protein interactions
What leads to polymer formation
Head-to-tail association leads to polymer formation
What is the ARP complex
7 sub unit protein complex and role in the regulation of actin cytoskeleton
What occurs after the branching of nucleation via the ARP complex
1st step in formation of new phase/ structure via self assembly
What is type II myosin
Type II myosin forms “double-headed” dimers => dimers then self assemble into bipolar thick filaments
What is sarcomere contraction driven by
Myosin force generation on actin
What are the building blocks of microtubules
A dimmer of alpha (a-tubulin - GTP) and beta tubulin (B-tubulin - taxol and GDP)
What is the centrosome
Primary microtubules organising centre and are loose assemblies built around centrioles
What is the effect of GDP tubulin on microtubule lattice
Makes microtubule lattice unstable
What is the result of the loss of GTP cap
Leads to self un-peeling and microtubule catastrophe
What are the roles of microtubules in cells
1) internal organisation of cell - moving vesicles + positioning organelles
2) chromosome segregation - mitotic spindle
3) moving fluids or cells in fluids - e.g cilia + flagella
What are the roles of the cilia and flagella
Both used for moving fluids and moving fluids in
What are the symptoms of kartageners syndrome and situs inversus
-difficulty breathing
-chronic stiffness
-male and female infertility
-situs inversus
What are the properties of intermediate filaments
-high tensile strength
-resistant to treatments that disrupt actin filaments and MT
-no nucleotide binding
-assemble by coiled-coil interactions
What is a heptad
7 residues
What is nuclear lamina
Disassembly during cell division
What are the kinetic effects of strong interactions
Strong interactions => kinetically more stable than weak interactions
How does the process of immunofluorescence light microscopy work
Primary antibodies against protein of interest bound to fixed cell => fluorescent secondary antibody is used to light up the structure
How are actin filaments formed
By head to tail non-covalent associated of individual actin molecules
What does actin do in filament assembly
Actin binds and hydrolyses ATP during filament assembly
Where does most of actin filament growth occur from
Occurs at plus ends
What are the features which use organised microtubule arrays for directed transport
Proximal vs distal (neuron)
Apical vs basolateral (epithelial cells)
Center vs perimeter (pigment cell)
What are actin filaments
Polar, non-covalent polymers involved in cell organisation, cell movement and basis of muscle contraction
