The Cytoskeleton Flashcards
Name five functions of the cytoskeleton
- Provide structure and support
- Intracellular transport
- Hold organelles in place
- Generate force for cell movement
- Helps in cell division
What is the difference between dynein and kinesin motors?
Kinesins move toward +end of Microtubules (to cell membrane)
Dyneins move toward -end of Microtubules (toward centriole)
What bonds are not present in Microtubules?
Covalent bonds
What bonds and/or forces will be present in cytoskeletal fibre assembly?
Ionic bonds
Hydrogen bonds
van der Waals forces
What is the energy source and binding site in tubular subunits?
GTP
What is the energy source of micro filaments?
ATP
Do micro filaments have polarity?
Yes
Do intermediate filaments have polarity? Why?
The a-helical monomer and the b-helical are coiled together anti parallel, giving a neutral charge
Which of the cytoskeletal fibres requires no energy to assemble?
Intermediate filaments
What can be carried in the vesicles by motor proteins? (5)
Organelles, proteins, enzymes, neurotransmitters, and pigments
How are motor proteins powered?
ATP
In the flagella, what linker protein holds the doublets together? It allows the Microtubules that have slid over to pull back
Nexin
What motor protein allows Microtubules to slide over each other in the flagella and cilia?
Dynein
How many double Microtubules surround the middle two in a flagellum or cillum?
9
What does the ECM primarily consist of?
Things secreted by the cell
What is an important component of the ECM, of which collagen is a member?
Glycoproteins
What are some of the functions of the ECM?
Can form complex structures outside the cell
Cell adhesion
Embryonic development
Why is collagen valued?
Because of its great tensile strength and elasticity
What determines the consistency of the ECM?
The amount of proteoglycan layers and the number of linkages it has with polysaccharide molecules
When will the consistency of the ECM be jelly like?
High amounts of linkages between proteoglycans and the polysaccharides because those trap lotsa water
What glycoprotein is responsible for anchoring the ECM to the cell?
Fibronectin
How does Fibronectin anchor the ECM to the cell?
One end acts as a barbed hook that anchors in the ECM, and the other side threads through membrane proteins called integrins. It then binds to micro filaments on the other side.
How do the integrins determine how well the ECM holds to the cell?
By how many there are
What are Matrix Metallo - Proteins?
These guys produce and degrade the ECM allowing the cell to move
Where are intermediate filaments found?
Form cage around the nucleus and are underneath the plasma membrane
Which of the Tubulin dimers has its active site covered?
Alpha
What is a single row of heterodimers assembled in a single row called?
Protofilament
What are the Microtubules that attach to the chromosomes and pull them apart?
Kinetocore Microtubules
What is the finger like projection at the end of a neuron called?
Filopodium
What is the web like portion at the end of a neuron called?
Lamellipodia
