Cell Structure: Cytoskeleton and Microtubules
42 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What role do microfilaments play in intestinal epithelial cells?

  • Serve as storage for cellular nutrients
  • Facilitate cell motility through contraction
  • Support the structure of the plasma membrane
  • Make up the core of microvilli (correct)

How do actin-myosin interactions contribute to muscle cells?

  • Enhance the stability of the cell membrane
  • Increase cellular permeability to nutrients
  • Mediate the contraction of muscle cells (correct)
  • Facilitate DNA replication

What defines pseudopodia in amoeba?

  • Permanent extensions for nutrient storage
  • Transient structures for locomotion (correct)
  • Rigid appendages for defense
  • Fixed structures for shape maintaining

Which of the following is NOT a function of microfilaments?

<p>Providing structural stability to the nucleus (D)</p> Signup and view all the answers

In muscle cells, which process is primarily driven by the actin-myosin contractile system?

<p>Contraction of muscle fibers (B)</p> Signup and view all the answers

What is the primary function of dynein in the context of microtubules?

<p>Transporting cargo from the periphery to the cell center (C)</p> Signup and view all the answers

Which statement regarding kinesin is correct?

<p>It functions in transporting cargo toward the cell periphery. (A)</p> Signup and view all the answers

What type of motor protein is responsible for transport toward the plus end of the microtubule?

<p>Cytosolic kinesin (C)</p> Signup and view all the answers

In the context of cellular transport, what do motor proteins utilize to carry vesicles?

<p>Microtubules (D)</p> Signup and view all the answers

What characteristic distinguishes the role of kinesin and dynein?

<p>Kinesin moves toward the + end, while dynein moves toward the - end of microtubules. (B)</p> Signup and view all the answers

What is the primary function of fibronectin within the extracellular matrix (ECM)?

<p>Promotes cell attachment to ECM components (C)</p> Signup and view all the answers

Which collagen type is most abundant in the human body and is crucial for tissue structure?

<p>Type I (A)</p> Signup and view all the answers

What structural motif is characteristic of collagen's helical chains?

<p>Gly-X-Y (D)</p> Signup and view all the answers

Which collagen type is primarily found in cartilage?

<p>Type II (D)</p> Signup and view all the answers

Which syndrome is associated with reduced production of Type I collagen?

<p>Osteogenesis imperfecta (OI) type I (B)</p> Signup and view all the answers

What cells primarily produce collagen in the extracellular matrix?

<p>Fibroblasts (B)</p> Signup and view all the answers

Which type of collagen is associated with the basement membrane?

<p>Type IV (C)</p> Signup and view all the answers

What is the primary role of the basement membrane?

<p>Separates epithelial cells from connective tissue (C)</p> Signup and view all the answers

What is a primary function of the plant cell wall?

<p>Protects the plant cell from damage (C)</p> Signup and view all the answers

Which of the following materials primarily composes plant cell walls?

<p>Cellulose fibers (C)</p> Signup and view all the answers

What distinguishes plant cell walls from those of animal cells?

<p>Composition of cellulose (C)</p> Signup and view all the answers

Which statement about the cell wall is incorrect?

<p>It is present in all types of cells. (A)</p> Signup and view all the answers

Which of these components is found in prokaryotic cell walls, but not in plant cell walls?

<p>Peptidoglycan (B)</p> Signup and view all the answers

What role does the plant cell wall play in regulating water uptake?

<p>It prevents excessive water uptake. (D)</p> Signup and view all the answers

Which organisms besides plants are known to possess cell walls?

<p>Prokaryotes and fungi (A)</p> Signup and view all the answers

What prevents plant cells from taking in too much water?

<p>Cell walls (C)</p> Signup and view all the answers

What is the primary role of the centrosome in the cytoskeleton?

<p>Microtubule organization (D)</p> Signup and view all the answers

Which of the following structures is a component of the cytoskeleton?

<p>Microtubules (B)</p> Signup and view all the answers

What distinguishes flagella from cilia?

<p>Cilia drive fluid movement across cell surfaces (C), Flagella are longer and fewer in number (D)</p> Signup and view all the answers

Which of the following correctly describes microfilaments?

<p>Involved in muscle contraction (C)</p> Signup and view all the answers

What is a common extracellular component of animal cells?

<p>Collagen (D)</p> Signup and view all the answers

Which type of junction is primarily responsible for the direct communication between animal cells?

<p>Gap junctions (D)</p> Signup and view all the answers

How do plant cells typically connect with each other?

<p>Plasmodesmata (B)</p> Signup and view all the answers

Which statement about intermediate filaments is true?

<p>They provide mechanical support to cells (D)</p> Signup and view all the answers

Which motor protein primarily facilitates movement towards the cell periphery along microtubules?

<p>Kinesin (B)</p> Signup and view all the answers

What is the primary function of cilia in eukaryotic cells?

<p>Enabling locomotion and movement of fluids (C)</p> Signup and view all the answers

Which statement accurately describes the motion of flagella?

<p>They have a snakelike undulating motion. (B)</p> Signup and view all the answers

Which of the following best describes the structure of cilia?

<p>Specialized arrangements of microtubules (A)</p> Signup and view all the answers

What is a notable difference between flagella and cilia regarding their number per cell?

<p>Cilia are typically more numerous than flagella. (D)</p> Signup and view all the answers

What type of movement pattern do cilia use to propel the cell?

<p>Back-and-forth motion (C)</p> Signup and view all the answers

Which end of a microtubule is typically associated with the forward motion of kinesin?

<p>(+) end (B)</p> Signup and view all the answers

Which type of cell structure would likely utilize dynein for its function?

<p>Tracheal cells using cilia (D)</p> Signup and view all the answers

Flashcards

Microtubules: Structure and Function

Microtubules are long, hollow, cylindrical structures found in eukaryotic cells. They play a vital role in cell shape, movement and intracellular transport.

Motor Proteins: Motility

Motor proteins are responsible for moving cargo along microtubules. They have specific regions that bind to microtubules and to cargo.

Dynein: Retrograde Transport

Dynein is a motor protein that moves cargo from the cell periphery towards the cell center. It moves along microtubules in a retrograde direction, from the plus end to the minus end.

Kinesin: Anterograde Transport

Kinesin is a motor protein that moves cargo from the cell center towards the cell periphery. It moves along microtubules in an anterograde direction, from the minus end to the plus end.

Signup and view all the flashcards

Vesicle Transport: Microtubule Highway

Vesicles, small membrane-bound sacs, are transported along microtubules by motor proteins. These vesicles carry various cellular cargo, including organelles and proteins, throughout the cell.

Signup and view all the flashcards

Cytoskeleton

A network of protein fibers that helps maintain cell shape, anchors organelles, and facilitates movement. It's like the skeleton of a cell, giving it structure and allowing it to move around.

Signup and view all the flashcards

Microfilaments

Long, thin fibers made of the protein actin. They help with cell movement, muscle contraction, and the division of cells.

Signup and view all the flashcards

Microtubules

Rod-like structures made of the protein tubulin. They help transport materials within the cell, form the basis for cilia and flagella, and are involved in cell division.

Signup and view all the flashcards

Intermediate Filaments

Fibers that are intermediate in size between microfilaments and microtubules. They provide structural support and help anchor organelles.

Signup and view all the flashcards

Centrosome

A region near the nucleus where microtubules are assembled. It plays a crucial role in cell division.

Signup and view all the flashcards

Cilia

Hair-like structures that propel fluids past the cell surface. They are found on cells lining the respiratory tract and help move mucus out of the lungs.

Signup and view all the flashcards

Flagella

Whip-like structures that propel whole cells. Sperm cells have flagella that allow them to swim.

Signup and view all the flashcards

Extracellular Matrix

A network of fibers and other molecules that forms outside the cell membrane. It helps support and protect the cell, and can be involved in cell-to-cell communication.

Signup and view all the flashcards

Plant Cell Wall

A rigid, supportive structure found outside the cell membrane of plant cells, providing structural support, protection, and regulating water uptake.

Signup and view all the flashcards

Cellulose

A complex polysaccharide that is the primary component of plant cell walls. It forms strong, fibrous structures that provide structural support.

Signup and view all the flashcards

Plasmodesmata

Tiny openings in the cell walls of adjacent plant cells, allowing for communication and passage of substances between them.

Signup and view all the flashcards

Primary Cell Wall

The outermost layer of the cell wall that provides primary structural support and is made of cellulose fibers embedded in a matrix of other polysaccharides.

Signup and view all the flashcards

What is the function of microfilaments in intestinal microvilli?

Microfilaments, primarily composed of actin, form the core support structure for microvilli, finger-like projections on epithelial cells, especially in the intestines, that increase surface area for absorption.

Signup and view all the flashcards

How do microfilaments contribute to cell motility?

Microfilaments, including actin, play a key role in cell movement. They form temporary extensions called pseudopodia, which allow cells like amoeba to move and engulf food.

Signup and view all the flashcards

How does the actin-myosin contractile system contribute to muscle contraction?

Muscle cells contract due to the interaction of actin and myosin filaments. Myosin heads move along actin filaments, creating a pulling force that shortens the muscle cell.

Signup and view all the flashcards

What are pseudopodia and their function in cell movement?

Pseudopodia are temporary, finger-like projections formed by microfilaments, mainly actin, that extend from a cell's surface, enabling movement and engulfing food particles.

Signup and view all the flashcards

How do amoebas use microfilaments for movement and feeding?

Amoebas are single-celled organisms that use pseudopodia, formed by microfilaments, for locomotion (movement) and phagocytosis (engulfing food).

Signup and view all the flashcards

Microtubule Motor Proteins

Proteins that move along microtubule tracks, transporting vesicles or organelles within the cell. They have specific directions of movement: Kinesin moves towards the (+) end of the microtubule, while Dynein moves towards the (-) end.

Signup and view all the flashcards

Cilia and Flagella

A type of microtubule-based organelle responsible for movement. They are present in specific eukaryotic cells and have a specific arrangement of microtubules.

Signup and view all the flashcards

Flagella Motility Pattern

The direction of the motion of a flagellum. It moves in a snake-like motion, propelling the cell in the same direction as the flagellum's axis.

Signup and view all the flashcards

Cilia Motility Pattern

The unique movement of cilia, involving a back-and-forth motion that pushes the cell in a direction perpendicular to the cilium's axis.

Signup and view all the flashcards

Plus (+) and Minus (-) Ends of Microtubules

The (+) end of microtubules is where kinesin proteins attach and move towards. The (-) end is where dynein proteins attach and move towards.

Signup and view all the flashcards

Extracellular Matrix (ECM)

A group of specialized proteins that make up the structural framework of tissues and organs; they provide support, adhesion, and organization.

Signup and view all the flashcards

Integrins

A family of transmembrane proteins that act as cell surface receptors for ECM components, mediating cell adhesion, migration, and signaling.

Signup and view all the flashcards

Collagen

A protein with high tensile strength, found in various tissues like skin, tendon, and bone.

Signup and view all the flashcards

Basement Membrane (Basal Lamina)

A specialized ECM type that separates epithelial cells from underlying connective tissue.

Signup and view all the flashcards

Fibronectin

A large protein that promotes cell adhesion to the ECM and plays a crucial role in cell migration and tissue development.

Signup and view all the flashcards

What is the medical condition associated with reduced production of Type I collagen?

Osteogenesis imperfecta (OI), a genetic disorder characterized by brittle bones.

Signup and view all the flashcards

What medical condition is associated with deficiency of Type III collagen?

Ehlers-Danlos syndrome, a group of inherited disorders affecting connective tissues, leading to hyper-extensible skin, joint hypermobility, and fragile blood vessels.

Signup and view all the flashcards

What condition is associated with defective Type IV collagen?

Alport syndrome, a genetic disorder that affects the kidneys, ears, and eyes.

Signup and view all the flashcards

Study Notes

Cell Structure and Components

  • The cytoskeleton is a network of filaments throughout the cytoplasm
  • It is composed of three types of filaments:
    • Microfilaments (actin filaments): the thinnest components
    • Intermediate filaments: filaments with middle-range diameters, composed of different protein types (e.g., keratin)
    • Microtubules: tubulin filaments, the thickest of the three components
  • Cytoskeleton functions:
    • Mechanical support for the cell
    • Maintains cell shape
    • Organizes cell structures and activities
    • Allows cell movement
    • Can be assembled and disassembled to change cell shape

Cytoskeleton: Microtubules

  • Microtubules are hollow rods, the thickest component of the cytoskeleton
  • They are helical polymers made of tubulin monomers
  • Microtubule functions include:
    • Mitotic spindle formation, separating chromosome copies in dividing cells
    • Shaping the cell
    • Guiding organelle movement

Microtubules: Centrosomes and Centrioles

  • The centrosome is a microtubule-organizing center (MTOC)
  • It consists of a centriole pair
  • Located near the nucleus (cell center)
  • Found only in animal cells
  • Yeast and plant cells do not have centrosomes but may contain similar structures
  • Centrosome structure: has 2 centrioles
  • Centrioles are composed of nine triplets of microtubules (9+0 arrangement)
  • Pericentriolar material surrounds the centrosome
  • Contains y-tubulin that facilitates the nucleation of microtubules

Microtubules and Motility

  • Microtubules act as "monorails" for the movement of vesicles, organelles, and chromosomes.
  • Motor proteins (cytoplasmic motor proteins) move cargo along microtubules:
    • Dynein: transports material from periphery towards cell center (+ to - end)
    • Kinesin: transports materials from cell center toward periphery (- to + end)

Cilia and Flagella

  • Cilia and flagella are permanent locomotor appendages of some eukaryotic cells
  • They contain specialized arrangements of microtubules (9+2 arrangement of microtubules)
  • Cilia move in back-and-forth motion
  • Flagella move in a snakelike motion
  • Axoneme: the central strand of cilia and flagella, composed of microtubules
  • Axonemal dynein: responsible for bending movements of cilia and flagella
  • Basal body: a protein structure found at the base of eukaryotic cilia and flagella, consists of nine triplets microtubules (9+0 arrangement)

Microfilaments (Actin Filaments)

  • Microfilaments are solid rods, composed of two intertwined strands of actin
  • Can be assembled and disassembled to change cell shape
  • Act in muscle contraction
  • Function in cell motility in organisms such as amoebas.
  • Also responsible for microvilli core structures in the intestinal epithelial cells and cytoplasmic streaming processes.

Intermediate Filaments

  • Intermediate filaments are larger than microfilaments but smaller than microtubules
  • They are more permanent than microfilaments or microtubules
  • Function: provide support to cell shape and fix organelles in place
  • Intermediate filaments help make up desmosomes in epithelial cells
  • Some examples of IF types include keratin, desmin, vimentin, neurofilaments, GFAP and lamins.

Extracellular Components

  • Most animal cells are covered by the extracellular matrix (ECM)
  • ECM consists of glycoproteins and proteoglycans
  • Glycoproteins include collagen, fibronectin, and laminin
  • Proteoglycans are proteins plus glycosaminoglycans
  • ECM functions overall are to provide support, facilitate adhesion, cell movement, and regulate gene expression.

Plant Cell Walls

  • Plant cell walls are found outside of the plasma membrane
  • They are an extracellular structure distinct from animal cell walls
  • Plant cell walls consist mostly of cellulose fibers embedded in other polysaccharides and proteins
  • Functions of plant cell walls include: protection for the cell, maintaining its shape, and preventing excessive uptake of water.

Intercellular Junctions

  • Intercellular junctions are important for cell coordination and communication
  • Plant cells have plasmodesmata: channels that connect neighboring plant cells and allow the exchange of molecules
  • Animal cells have tight junctions, desmosomes, and gap junctions.
    • Tight junctions prevent intercellular leakage of fluid.
    • Desmosomes fasten cells together into strong sheets.
    • Gap junctions provide channels allowing ion and small molecule exchange.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Quiz Team

Related Documents

Topic 5. Cell Part B PDF

Description

This quiz explores the structure and functions of the cytoskeleton, focusing on microtubules and their role within the cell. It covers the different components of the cytoskeleton, such as microfilaments and intermediate filaments, as well as the specific functions that microtubules perform in cellular processes. Test your knowledge on this essential aspect of cell biology!

More Like This

Use Quizgecko on...
Browser
Open
Browser
Browser