Flashcards in FInal 4 Deck (101):
Provide mechanical strength in cells
Used for cell locomition and cell surface shape
Determine position of organelles and direct movement
Specialized structures that increase absorptive surface area in epithelial cells
What kind of cytoskeletal material are nuclear lamina made from?
Cytoskeletal material used for flagella
Birthplace of all cytoplasmic MTs
What are MTs protofilaments?
Polymers of alpha-beta tubulin heterodimers
Which subunit of MT does not cleave GTP to GDP?
How many MT protofilaments assemble to form a tube?
What do actin monomers bind?
How many actin protofilaments intertwine to form a fiber?
What do two monomers of IFs form?
What do two coiled-coil dimers of IFs form?
Staggered tetramer in an antiparallel arrangement
How many protofilaments of IFs twist into a ropelike filament?
What is the rate-limiting step for actin filament assembly?
What is the nucleation process of filament assembly dependent upon?
Free actin and tubulin monomers are bound by what?
What happens when a GTP cap is lost?
MT will fray and shrink
Name for when MTs shrink due to loss of GTP cap
MTs regrowing after a catastrophe
What does taxol do to MTs?
Stabilizes them, essentailly killing rapidly dividing cells
Complex responsible for initiating MTs
What end of MTs are inside MTOC
Complex responsible for initiating actin arrays
Where do Arp2/3 usually nucleate?
What angle do Arp2/3 bind to sides of existing actin filaments to form branches?
2 actin monomer binding proteins
Actin filament destabilizing protein
Actin filament severing protein
2 actin filament capping proteins
MT binding protein
MT filament binding protein
2 MT filament destabilizer
MT-based plus-end directed motor
MT-based negative-end directed motor
WHat happens when myosin is treated with trypsin?
Heads and a small piece of tail are released from the tail
What happens when myosin is treated with papain?
Splits the heads up and removes the tail
Which myosin moves towards the minus end?
What is the fastest motor protein?
Which motor protein "walks"
While ____ binds tightly with bound NTP, ____ binds tightly without NTP
One dimensional finger-like projection of actin
Two dimensional sheet-like structure of actin
Three dimenisional projections used for phagocytosis
3 extracellular stimuli receiving g-proteins that actin cytoskeleton responds to
Rho, Rac, Cdc42
Produces large numbers of actin stress fibers
Yields large numbers of filopodia
Generates very large lamellapodia that encircles the cell
How long is S-phase
Comittment to undergo another round of cell division
Start point (G1)
Key part of prophase
Key part of prometaphase
Breakdown of nuclear envelope
Key part of metaphase
Chromosomes aligned at equator
Key part of anaphase
Chromosomes are being pulled apart
Key part of telophase
Chrosomes are at the poles
How is centrisome duplication triggered?
MTs that radiate in all directions
Attach end-on to kinetochore
Span distance between bipolar spindle
Push overlap MTs against each other
PUll spindles towards each other
Attach chromosomes to MTs for positioning
Attach astral MTs to periphery and pull spindles apart
3 forces that move chromosomes on the spindle
Kinetochore generated poleward force, poleward MT flux, polar ejection force
What force is Anaphase A defined by?
Kinetochore generated poleward force and MT flux
What force is Anaphase B defined by?
SPindle poles move apart, dynein pulling on astral MTs
Visible pucker in PM during cytokinesis
How do cleavage furrows form?
Contraction along actomyosin contractile ring
Region between future duaghter cells
What is the organization and deposition of contractile ring regulated by?
WHat kind of proteins are cyclin dependent kinases?
4 classes of cyclins
G1/S, S, M, G1
Bind to Cdks at the end of G1 and commit the cell to DNA replication
Bind to Cdks during S-phase and are required for the initiation of DNA replication
Promote events of mitosis and G2/M transition
Promote the passage through "start" point by helping govern G1/S cyclins
2 steps of Cdk activation
Cyclin binding alters conformation of T-loop, CAK phosphorylates a threonine residue within T-loop
Inhibitory protein of Cdk
Inhibitory protein of Wee1
General family of inhibitor proteins of Cyclin-Cdk
CKI (Cdk inhibitor)
Responsible for initiating S-phase by destruction of G1-Ss cyclins and CKIs
Responsible for initiating M-phase by destruction of M cyclins and regulators
3 enzymes that function in series for attachment of ubiquitin
E1, E2, E3
What activates APC/C?
Initiate DNA replication once per cycle and ensures that every base of DNA is faithfully replicated once
Where does DNA replication begin?
COmplex of initiator proteins that assembles on ORF during late mitosis
WHat does preRC mature into?
What mediates preinitiation complex?
First two molecules nucleates by ORC complex
What does S-cdk phosphorylate to allow replication machinery to work?
How is Cdt1 bound until it is liberated by S-Cdk
What is geminin destoryed by?
What are duplicated chromosomes held together by?
When triggers entry into mitosis?
Accumulation of M-cyclins
Phosphatase that removes the brakes on the regulatory factors stopping M-Cdk
What triggers siter-chromatid separation?
Protein that uses negative feedback to block APC/C from initiating sister-chromatid separation