Plant Cell Wall 4
57 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 is the main function of the plant cell wall?

  • To support and protect the cell (correct)
  • To allow cell movement
  • To store nutrients
  • To enable photosynthesis

    • Plant cell walls are more rigid than those of animal cells.

    True

    Who observed and named cells for the first time using cork?

    Robert Hooke

    The wall that forms during cytokinesis between daughter plant cells is known as the ______.

    <p>cell plate</p> Signup and view all the answers

    Match the following terms related to plant cell walls with their descriptions:

    <p>Primary cell wall = Thin and extensible wall formed during early cell division Secondary cell wall = Rigid wall that develops after cell growth stops Meristems = Regions where new plant cells are produced Cytokinesis = Process that leads to the formation of the cell plate</p> Signup and view all the answers

    Which part of the plant cell wall retains its primary function after cell growth stops?

    <p>Primary cell wall</p> Signup and view all the answers

    All plant cells have the same thickness in their cell walls.

    <p>False</p> Signup and view all the answers

    What is formed by cementing together the walls of neighboring plant cells?

    <p>Intact plant</p> Signup and view all the answers

    What is the primary role of lignin in secondary cell walls?

    <p>To make the walls waterproof and hard</p> Signup and view all the answers

    The primary cell wall is permanent and rigid.

    <p>False</p> Signup and view all the answers

    What is turgor pressure and its significance in plant cells?

    <p>Turgor pressure is the hydrostatic pressure developed inside a plant cell due to water intake, driving cell expansion and maintaining rigidity.</p> Signup and view all the answers

    Cellulose microfibrils are formed from bundles of about _____ cellulose chains.

    <p>18</p> Signup and view all the answers

    Match the following components with their descriptions:

    <p>Cellulose = Major constituent of plant cell walls Pectin = Hydrated matrix in which cellulose is embedded Cross-linking glycan = Polysaccharides that help link cellulose microfibrils Microtubules = Control orientation of cellulose deposition</p> Signup and view all the answers

    What is the main role of lignin in plant cell walls?

    <p>To act as a waterproof filler</p> Signup and view all the answers

    Cellulose is the most abundant organic macromolecule on Earth.

    <p>True</p> Signup and view all the answers

    What type of pressure is generated in plant cells due to osmotic imbalance?

    <p>Turgor pressure</p> Signup and view all the answers

    The plant cell wall is primarily composed of cellulose and __________.

    <p>lignin</p> Signup and view all the answers

    Match the following components with their respective roles in plant cell walls:

    <p>Cellulose = Tensile strength Pectin = Compression resistance Lignin = Waterproof filler Cross-linking glycans = Stabilization of cellulose microfibrils</p> Signup and view all the answers

    Which of the following best describes the primary cell wall?

    <p>Consists of cellulose microfibrils and pectin</p> Signup and view all the answers

    Plant cell walls are rich in nitrogen-containing polymers.

    <p>False</p> Signup and view all the answers

    What is the main driving force for cell expansion during growth in plants?

    <p>Turgor pressure</p> Signup and view all the answers

    During photosynthesis, plants create biomass primarily from __________ and lignin.

    <p>cellulose</p> Signup and view all the answers

    Which structural component helps to hold the cellulose microfibrils together?

    <p>Cross-linking glycans</p> Signup and view all the answers

    Turgor pressure can reach up to 10 atmospheres in plant cells.

    <p>True</p> Signup and view all the answers

    What is the composition of the matrix in primary cell walls?

    <p>Pectin</p> Signup and view all the answers

    The tensile strength of cellulose allows plant cells to develop __________ pressure.

    <p>turgor</p> Signup and view all the answers

    Match the following types of plant cell walls with their key characteristics:

    <p>Primary Cell Wall = Flexible and growing Secondary Cell Wall = Rigid and permanent Cellulose Microfibrils = Provide tensile strength Pectin Network = Hydrated polysaccharides</p> Signup and view all the answers

    Which component is richest in the middle lamella?

    <p>Pectin</p> Signup and view all the answers

    Cross-linking glycans have the same consistency in all plant species.

    <p>False</p> Signup and view all the answers

    What is the primary role of pectins in plant cell walls?

    <p>To cement adjacent cells together.</p> Signup and view all the answers

    The _____ pressure inside the cell drives its expansion.

    <p>turgor</p> Signup and view all the answers

    Match the following components with their primary function:

    <p>Cellulose = Provides structural support Pectin = Cements adjacent cells Cross-linking glycans = Links cellulose microfibrils Proteins = Contribute to remodeling and turnover</p> Signup and view all the answers

    What type of bond helps to cross-link cellulose microfibrils?

    <p>Hydrogen bonds</p> Signup and view all the answers

    Cellulose is synthesized by enzymes found in the endoplasmic reticulum.

    <p>False</p> Signup and view all the answers

    How many CESA genes are required for primary cell wall synthesis?

    <p>Three</p> Signup and view all the answers

    Certain pectins are abundant in the _____, a region that cements together adjacent cell walls.

    <p>middle lamella</p> Signup and view all the answers

    Match the following processes with their descriptions:

    <p>Cell expansion = Involves turgor pressure and wall remodeling Cell wall loosening = Allows expansion in specific directions Cross-linking with Ca2+ = Leads to the formation of a semirigid gel Cell wall synthesis = Spun out by enzyme complexes at the plasma membrane</p> Signup and view all the answers

    What is the function of proteins in the cell wall?

    <p>Aid in cell wall turnover and remodeling</p> Signup and view all the answers

    The orientation of cellulose microfibrils does not affect the direction of cell expansion.

    <p>False</p> Signup and view all the answers

    What common process is underpinned by the regulated separation of cells at the middle lamella?

    <p>Ripening of tomatoes or abscission of leaves.</p> Signup and view all the answers

    Cellulose microfibrils must either slide past one another or become more _____ for the cell wall to stretch.

    <p>widely separated</p> Signup and view all the answers

    What is the role of the complex of enzymes known as cellulose synthase?

    <p>To synthesize cellulose from UDP-glucose</p> Signup and view all the answers

    What primarily determines the orientation of newly deposited cellulose microfibrils?

    <p>The cortical microtubules</p> Signup and view all the answers

    Microtubules are no longer needed once the orientation of microfibrils is established.

    <p>False</p> Signup and view all the answers

    What happens to the orientation of microfibrils when a microtubule-depolymerizing drug is applied?

    <p>Developmental switches in orientation are blocked.</p> Signup and view all the answers

    The _____ of microtubules usually correlates with the orientation of cellulose microfibrils being deposited.

    <p>cortical array</p> Signup and view all the answers

    How do cellulose-synthesizing rosettes move during the synthesis of cellulose?

    <p>As they elongate their microfibrils</p> Signup and view all the answers

    Plant cells are capable of changing their direction of growth with no external influence.

    <p>False</p> Signup and view all the answers

    During which stages of plant cell development is the orientation of microfibrils relevant?

    <p>Both primary and secondary cell wall deposition.</p> Signup and view all the answers

    When treated with a microtubule-depolymerizing drug, cells may continue to deposit _____ in their preexisting orientation.

    <p>microfibrils</p> Signup and view all the answers

    What factor allows for a change in the orientation of cellulose microfibrils?

    <p>Active cortical microtubules</p> Signup and view all the answers

    Match the following components with their roles in cellulose synthesis:

    <p>Cortical Microtubules = Determine orientation of deposition Cellulose Synthase Rosettes = Synthesize and deposit cellulose microfibrils Cell Wall = Provide structure and rigidity to plants Cortical Actin Filaments = Direct deposition at specific sites</p> Signup and view all the answers

    Cortical actin filaments do not influence wall deposition.

    <p>False</p> Signup and view all the answers

    What type of growth regulators can influence the reorientation of microtubules?

    <p>Auxins and ethylene.</p> Signup and view all the answers

    What is deposited concentrically in the cell wall?

    <p>Lamellae</p> Signup and view all the answers

    The area where cortical microtubules are located is found close to the _____ of the plasma membrane.

    <p>cytosolic face</p> Signup and view all the answers

    What structure in plant cells is primarily responsible for defining their morphology?

    <p>Cortical microtubule orientations.</p> Signup and view all the answers

    Study Notes

    Plant Cell Wall

    • Cellulose is the most abundant organic molecule on Earth and is the tensile strength component of the cell wall.
    • Lignin is a phenolic compound found in woody tissues and provides resistance to compression.
    • The primary cell wall is thin and extensible and forms during cell division.
    • The secondary cell wall is more rigid and forms after a cell has stopped growing.
    • Cellulose is made from glucose and forms microfibrils.
    • The middle lamella cements adjacent cells together.
    • Pectin is a polysaccharide that is highly hydrated and associated with cations.
    • Turgor pressure is caused by the osmotic imbalance between the cell interior and the external environment.
    • Cellulose synthase is a plasma membrane-bound enzyme complex that synthesizes cellulose.
    • Cortical microtubules are cytoskeletal elements that influence the orientation of cellulose microfibrils.
    • Actin filaments can also influence wall deposition.

    Cell Wall Structure

    • The plant cell wall consists of two major polysaccharide networks:
      • Cellulose and cross-linking glycans for tensile strength
      • Pectin for compression resistance.
    • Primary cell walls are composed of cellulose microfibrils, cross-linking glycans, and pectin.
    • Secondary cell walls contain lignin, which provides rigidity.

    Cell Wall Deposition

    • The orientation of cellulose microfibrils determines the direction of cell expansion.
    • Cellulose synthase complexes (rosettes) are integral membrane proteins that synthesize cellulose microfibrils on the outer face of the plasma membrane.
    • Cortical microtubules can act as boundaries to constrain the movement of cellulose synthase complexes.
    • The orientation of cortical microtubules can determine the axis along which new microfibrils are laid down.

    Functions of the Plant Cell Wall

    • Structural support: Provides rigidity and strength to the plant.

    • Protection: Encloses each cell individually.

    • Transport: Helps form channels for the movement of fluid in the plant.### Plant Cell Wall Structure

    • Plant cell walls are complex structures composed of cellulose microfibrils, cross-linking glycans, and pectin polysaccharides.

    • Cellulose microfibrils form highly ordered crystalline aggregates, with bundles of about 18 cellulose chains arranged in parallel arrays.

    • These cellulose chains are held together by hydrogen bonds, creating strong structures.

    • Cross-linking glycans are branched polysaccharides that help connect the cellulose microfibrils, forming a complex network.

    • Pectin polysaccharides are rich in galacturonic acid, creating a hydrated matrix that embeds the cellulose microfibrils.

    • The combination of cellulose microfibrils, cross-linking glycans, and pectin creates a strong and flexible framework for the cell wall.

    Secondary Cell Walls

    • In secondary cell walls, which are formed after the primary cell wall, lignin is deposited.
    • Lignin is a network of cross-linked phenolic compounds that strengthens the cell wall, making it waterproof, hard, and woody.
    • The presence of lignin is essential for the structural integrity and support of woody tissues, like the xylem.

    Cell Wall Growth and Shape

    • Microtubules, which are protein filaments, form an array within the cell that controls the orientation of newly deposited cellulose microfibrils.
    • The direction of the cellulose microfibrils, in turn, determines the direction of cell expansion.
    • Therefore, the arrangement of microtubules ultimately influences the final shape of the cell and, consequently, the overall shape of the plant.

    Studying That Suits You

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

    Quiz Team

    Description

    Test your knowledge about the structure and composition of plant cell walls. This quiz covers components like cellulose, lignin, pectin, and the processes involved in cell wall formation and maintenance. Understand the significance of various cellular structures in providing strength and resistance in plants.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser