p.5
Actin Cytoskeleton and Polymerization
What is the function of microvilli?
To increase surface area through actin bundles.
p.10
Intermediate Filaments Structure and Function
How are lamins organized in relation to the nucleus?
They form a network linked to the nuclear lamina.
p.6
Actin Cytoskeleton and Polymerization
What role does the cell cortex play at the lagging end of the cell?
It squeezes the back of the cell with myosin.
p.4
Actin Binding Proteins and Cellular Structures
What type of protein is dystrophin?
A support structure protein.
p.4
Actin Binding Proteins and Cellular Structures
What is the role of dystrophin in muscle cells?
It links the plasma membrane to the actin cytoskeleton.
p.4
Actin Binding Proteins and Cellular Structures
How does dystrophin contribute to muscle integrity?
By providing structural support to the plasma membrane.
p.10
Intermediate Filaments Structure and Function
What are lamins?
Intermediate filaments that support the nuclear membrane and help maintain the shape of the nucleus.
p.5
Actin Cytoskeleton and Polymerization
What are stress fibers and their function?
They bind to focal adhesions to facilitate cell movement.
p.10
Regulation of Cytoskeletal Dynamics
How dynamic are intermediate filaments compared to microtubules and actin?
They are dynamic, but not as much as microtubules or actin.
p.7
Myosin Motor Proteins and Muscle Contraction
How does myosin differ from kinesin and dynein in terms of movement?
Myosin can only move towards the + end, while kinesin and dynein can move in both directions.
p.8
Intermediate Filaments Structure and Function
What are lamins?
A type of intermediate filament found in the nucleus.
p.11
Regulation of Cytoskeletal Dynamics
How does the regulation of intermediate filaments differ from that of microtubules and actin cytoskeleton?
Intermediate filament stability is regulated by kinases and phosphatases, while MTs and actin are mainly regulated by binding and capping proteins.
p.3
Regulation of Cytoskeletal Dynamics
What proteins regulate actin polymerization and depolymerization?
Profilin (polymerization), Cofilin (depolymerization), and capping proteins.
p.5
Actin Cytoskeleton and Polymerization
What is the role of cortical actin in epithelial cells?
It is induced into stress fibers via epithelial-mesenchymal transition (EMT).
p.9
Intermediate Filaments Structure and Function
What is formed when four protofibrils come together?
An intermediate filament.
p.6
Actin Cytoskeleton and Polymerization
What stimulates branching in actin?
Adding laterally to existing actin.
p.9
Intermediate Filaments Structure and Function
What are two important types of intermediate filaments?
Keratins and their link to cadherins (desmosomes).
p.8
Intermediate Filaments Structure and Function
How do intermediate filaments grow?
On either end, due to their tetrameric structure.
p.11
Regulation of Cytoskeletal Dynamics
What is the role of kinases in the regulation of intermediate filaments?
Kinases break down intermediate filaments.
p.9
Intermediate Filaments Structure and Function
What is the primary function of intermediate filaments?
To provide structural support necessary for cell shape.
p.2
Motor Proteins: Kinesin and Dynein
What is the role of ATP hydrolysis in dynein?
Causes conformational changes which results in movement.
p.11
Intermediate Filaments Structure and Function
Why do intermediate filaments need to disassemble during mitosis?
To allow for cell division.
p.5
Actin Binding Proteins and Cellular Structures
What do adhesion belts consist of?
Tight junctions and adherens junctions.
p.9
Intermediate Filaments Structure and Function
Which types of cells benefit from intermediate filaments?
Both epithelial and mesenchymal cells.
p.7
Myosin Motor Proteins and Muscle Contraction
What happens to the filaments during muscle contraction?
The filaments move closer together.
p.8
Myosin Motor Proteins and Muscle Contraction
What happens to the Z disk during muscle contraction?
They come closer together.
p.1
Microtubule Associated Proteins (MAPs)
What do MAPs stand for?
Microtubule Associated Proteins.
p.11
Regulation of Cytoskeletal Dynamics
How do you disassemble intermediate filaments?
Through phosphorylation of serine residues, which disassembles them and prevents reassembly.
p.3
Actin Binding Proteins and Cellular Structures
Where are actin networks typically found?
At the inner plasma membrane and the leading edge of migrating cells.
p.9
Intermediate Filaments Structure and Function
What analogy is used to describe the role of intermediate filaments?
IFs are like the rope that holds the edges of the tent down.
p.1
Centrosome as Microtubule Organizing Center (MTOC)
What does MTOC stand for?
Microtubule Organizing Center.
p.1
Regulation of Cytoskeletal Dynamics
What do MT severing proteins do?
Destabilize microtubules.
p.11
Regulation of Cytoskeletal Dynamics
What is the role of phosphatases in the regulation of intermediate filaments?
Phosphatases help intermediate filaments come back together.
p.3
Actin Cytoskeleton and Polymerization
At which ends does actin grow?
Both - and + ends, but faster at the + end.
p.10
Intermediate Filaments Structure and Function
What is the primary function of intermediate filaments in epithelial cells?
To stabilize epithelial cells.
p.10
Regulation of Cytoskeletal Dynamics
Can intermediate filaments add or take away components?
Yes, they can add or take away from them, but they are less dynamic than microtubules or actin.
p.7
Myosin Motor Proteins and Muscle Contraction
What is the structure of the A band in a skeletal muscle sarcomere?
It contains Myosin II filaments.
p.1
Microtubule Associated Proteins (MAPs)
What are +TIPs?
+ end tracking proteins that stabilize microtubules and reduce catastrophe.
p.3
Actin Binding Proteins and Cellular Structures
What are some examples of cellular structures formed by actin?
Bundles (e.g., microvilli, filopodia) and networks (e.g., spectrin, filamin).
p.5
Actin Cytoskeleton and Polymerization
What are filopodia?
Finger-like projections that act as sensory appendages.
p.2
Motor Proteins: Kinesin and Dynein
What type of motor protein is kinesin?
MT + end motor protein (anterograde).
p.1
Microtubule Associated Proteins (MAPs)
How do MAPs affect microtubules?
They alter the stability and bundle microtubules.
p.5
Actin Cytoskeleton and Polymerization
What is the purpose of filopodia?
To explore the extracellular matrix (ECM) for movement cues.
p.8
Actin Cytoskeleton and Polymerization
What creates tension to pinch off one cell from another?
Constant contraction of the actin contractile ring.
p.2
Motor Proteins: Kinesin and Dynein
What type of motor protein is dynein?
MT - end motor protein (retrograde).
p.1
Regulation of Cytoskeletal Dynamics
What role does phosphorylation play in microtubule stability?
It causes MAPs to fall off, making microtubules more susceptible to destabilization.
p.1
Microtubule Structure and Function
Why are microtubules important?
They provide structural support and act as 'superhighways' for transport.
p.11
Regulation of Cytoskeletal Dynamics
What regulates the stability of intermediate filaments?
The opposing action of kinases and phosphatases.
p.3
Actin Binding Proteins and Cellular Structures
What is the role of actin binding proteins?
To organize actin into specific structures.
p.7
Myosin Motor Proteins and Muscle Contraction
What is the primary function of myosin in muscle contraction?
To facilitate contraction by moving filaments closer together.
p.7
Myosin Motor Proteins and Muscle Contraction
What is the direction of movement for myosin?
Myosin moves only towards the + end.
p.5
Actin Cytoskeleton and Polymerization
What happens if filopodia can move?
It leads to the formation of lamellipodia.
p.8
Myosin Motor Proteins and Muscle Contraction
What color results from staining myosin I and II with actin?
Orange, due to overlap of green (myosin) and red (actin).
p.1
Centrosome as Microtubule Organizing Center (MTOC)
In which direction do microtubules radiate from the MTOC?
Towards the cell periphery.
p.11
Intermediate Filaments Structure and Function
What happens when you sever a microtubule (MT)?
It falls apart with catastrophe.
p.7
Myosin Motor Proteins and Muscle Contraction
Does myosin change size during contraction?
No, myosin doesn’t change size.
p.2
Motor Proteins: Kinesin and Dynein
What causes movement in kinesin?
ATP hydrolysis causes conformational changes.
p.8
Intermediate Filaments Structure and Function
Where are intermediate filaments mostly found?
Cytoplasmic, but also in the nucleus.
p.3
Actin Cytoskeleton and Polymerization
What are the two forms of actin?
Monomeric globular (G-actin) and filamentous (F-actin).
p.10
Intermediate Filaments Structure and Function
What role does vimentin play in cells?
It allows for the integrity of mesenchymal cells.
p.11
Intermediate Filaments Structure and Function
How are proteins within intermediate filaments exchanged?
Segments in an existing intermediate filament can be taken out and replaced with new segments.
p.11
Intermediate Filaments Structure and Function
What happens when you cut an intermediate filament (IF)?
They won't fall apart; there is no catastrophe.
p.5
Actin Cytoskeleton and Polymerization
What is lamellipodium and its function?
A structure with branched actin that generates force along the plasma membrane to move the cell.
p.2
Motor Proteins: Kinesin and Dynein
What are the two components of kinesin?
Heavy chains (ATPase activity and bind MTs) and light chains (recognize cargo).
p.8
Intermediate Filaments Structure and Function
What are two characteristics that intermediate filaments do not have?
Polarity and motor proteins.
p.1
Microtubule Associated Proteins (MAPs)
What is an example of a +TIP?
End Binding protein 1 (EB1).
p.3
Actin Cytoskeleton and Polymerization
What structure do two G-actin monomers form?
F-actin (filamentous actin).
