Cell Biology - Cytoskeletal Components

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Questions and Answers

Which cytoskeletal component requires ATP for polymerization?

Intermediate filament

Actin filament (correct)

Microtubule

Keratin

What is the consequence of losing the GTP cap on a microtubule?

Creation of more tubulin

Mitosis promotion

Rapid disassembly (correct)

Increased stability

Which motor protein is primarily responsible for transporting vesicles along microtubules?

Spectrin

Myosin

Kinesin (correct)

Dystrophin

What role does actin polymerization play in cellular function?

Regulation of cytosol state Signup and view all the answers

Which of the following proteins is NOT involved in actin structure?

Kinesin Signup and view all the answers

Which cytoskeletal component has a stable structure and does not undergo dynamic assembly?

Intermediate filament Signup and view all the answers

Which statement about microtubules is false?

They require ATP for their polymerization. Signup and view all the answers

What is the primary function of dynein in relation to microtubules?

Transporting vesicles Signup and view all the answers

What is the main role of microtubules in cell division?

Regulate chromosomal movements Signup and view all the answers

How do intermediate filaments differ from actin and microtubules?

They are longer-lived, more permanent structures. Signup and view all the answers

Which statement regarding the effects of Velban on malignant cells is correct?

It prevents the formation of the mitotic spindle. Signup and view all the answers

What distinguishes cadherins from other cell adhesion molecules?

Cadherins mediate cell-to-cell adhesion through homophilic binding. Signup and view all the answers

Which component is responsible for resilience in the extracellular matrix?

Proteoglycans Signup and view all the answers

During cell division, what is the consequence of using a microtubule inhibitor like Velban?

The formation of the mitotic spindle will be disrupted. Signup and view all the answers

What is a key function of cadherins during cellular adhesion?

Connecting with cytoskeletal elements for stability Signup and view all the answers

What is the process called that allows actin monomers to assemble into filamentous actin?

Treadmilling Signup and view all the answers

What structure does the leading edge of a crawling cell form?

Lamellipodium Signup and view all the answers

Which statement correctly describes cranial nerve ganglia and axon fascicles in relation to nervous systems?

Autonomic nervous system – peripheral nervous system Signup and view all the answers

Which of the following describes a spinal nerve accurately?

Contains both afferent and efferent axons Signup and view all the answers

Where are the cell bodies of lower motor neurons located?

In the ventral horn of the spinal cord Signup and view all the answers

What type of nerve fibers are found in afferent pathways?

Afferent fibers Signup and view all the answers

Which part of the nervous system includes the brain and spinal cord?

Central nervous system Signup and view all the answers

What type of signal do efferent neurons send?

Motor signals from the brain to muscles Signup and view all the answers

How is innervation of skeletal musculature accomplished?

Involves both central and peripheral nervous system pathways Signup and view all the answers

Which type of cytoskeletal filament is typically found under the plasma membrane?

Actin microfilaments Signup and view all the answers

What is the primary influence on the stability and arrangement of actin filaments?

Actin-binding proteins Signup and view all the answers

Which structure is identified as the microtubule organizing center in a cell?

Centrosome Signup and view all the answers

Which actin-binding protein is primarily responsible for strengthening actin filaments?

Tropomyosin Signup and view all the answers

Where does the microtubule network exhibit a bright aggregation of filaments?

Around the nucleus Signup and view all the answers

Which function is NOT associated with actin-binding proteins?

Strengthening the plasma membrane Signup and view all the answers

Which of the following options correctly pairs an actin-bundling protein with its function?

Fibrin - Strengthens actin filaments Signup and view all the answers

What components make up the central nervous system?

Brain and spinal cord Signup and view all the answers

What is the primary component of the peripheral nervous system?

The spinal and cranial nerves Signup and view all the answers

What term refers to collections of nerve cell bodies in the peripheral nervous system?

Ganglia Signup and view all the answers

Which type of bond connects fatty acids to the glycerol backbone in fats?

Ester Signup and view all the answers

Which lipid headgroup is absent in canonical glycerol-phospholipids?

Galactose Signup and view all the answers

What is the main composition of the glycocalyx?

Carbohydrates Signup and view all the answers

Which description best fits the core of phospholipid bilayers?

Hydrophobic Signup and view all the answers

Which lipid motion is the fastest?

Protrusion Signup and view all the answers

Study Notes

Cytoskeletal Components

Actin Filaments: Require ATP for polymerization and undergo treadmilling.
Microtubules: Composed of tubulin, require GTP for polymerization; disassembly occurs with loss of the GTP cap.
Intermediate Filaments: Provide structural stability and do not undergo dynamic assembly or disassembly; keratin is a type of intermediate filament.

Microtubule Dynamics

Loss of the GTP cap leads to rapid disassembly of microtubules.
Dynein is a motor protein that facilitates the movement of intracellular cargo along microtubules.
Kinesin, another motor protein, assists in vesicle transport along microtubules.

Actin Polymerization Functions

Controls changes in the physical state of the cytosol, transitioning between gel and sol states.
Microtubules are responsible for chromosomal movement during cell division.
Intermediate filaments provide structural integrity, contrasting with the dynamic nature of actin and microtubules.

Effects of Chemotherapy on Microtubules

Velban inhibits microtubule formation, affecting the formation of the mitotic spindle and leading to cell mitotic arrest.
Actin polymerization remains unaffected by Velban, continuing processes like F-actin formation.

Cadherins in Cell Adhesion

Unique for their homophilic binding: they bind to other cadherins, facilitating cell-to-cell adhesion.
Different from other adhesion molecules that may bind to non-cadherin ligands or mediate cell-matrix adhesion.

Cytoskeletal Filament Identification

Identification in micrographs includes distinguishing features of actin microfilaments, intermediate filaments, and microtubules.
Actin microfilaments are primarily located beneath the plasma membrane, while microtubules are organized around centrosomes.

Properties of Actin Filaments

Stability and function governed by actin-binding proteins, which play roles such as strengthening, bundling, and regulating transformation states (gel to sol).
Myosin II family is involved in the sliding filament mechanism.

Nervous System Components

Peripheral Nervous System (PNS): Composed of cranial and spinal nerves; contains ganglia where nerve cell bodies cluster.
Central Nervous System (CNS): Made up of the brain and spinal cord; nerve fibers are termed tracts in the CNS and nerves in the PNS.
Spinal nerves consist of both afferent (sensory) and efferent (motor) axons.

Lipid Dynamics

Flip-Flop Motion: Slowest lipid motion; requires proteins like flippases for lipid distribution across bilayers.
Bond Formation: Ester bonds connect fatty acids to glycerol in fats.
Glycocalyx: Primarily composed of carbohydrates like glycolipids and glycoproteins, forming a protective layer outside the cell membrane.

Phospholipid Characteristics

The core of phospholipid bilayers is hydrophobic, facilitating the formation of lipid bilayers.
Phospholipases, particularly type C, cleave phosphatidylinositol 4,5 bisphosphate, leading to the generation of inositol trisphosphate.

Fastest Lipid Motion

Protrusion is the fastest motion among lipid movements, distinguishing it from other motions like lateral diffusion and rotational diffusion.

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Description

This quiz focuses on the key components of the cytoskeleton, specifically on the role of actin filaments. Participants will learn about the dynamic nature of these structures, their polymerization process, and their functional significance in cells.