Plant Cell Walls Overview
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Questions and Answers

What is the major component of the cell wall?

Cellulose

What is the substance between plant cells?

Middle lamellae

What forms the primary cell wall?

Cellulose microfibrils, pectin, hemicellulose, soluble proteins

How does the protein extensin benefit the cell?

<p>Increases cell extensibility, and can cross link to add cell strength, dehydrating it and stopping it from growing further.</p> Signup and view all the answers

What are the functions of the cell wall?

<p>Structure/cell morphology, protection from pathogens, prevents excess water uptake</p> Signup and view all the answers

In what ways can a plant cell expand?

<p>The plant cell will expand in all directions simultaneously, or at right angles of the long axis, increasing its length.</p> Signup and view all the answers

In what ways does the cell wall protect a plant?

<p>The rigidity of the cell wall protects the cell from pathogens and insects, however if a neighboring cell is infected with a pathogen, the cell walls can secrete chemicals to prevent the infection.</p> Signup and view all the answers

How does the secondary cell wall differ from the primary cell wall?

<p>Not all plants have secondary cell walls, they are much thicker, having several layers of microfibrils orientated in different manners. The secondary cell wall also contains lignin. Secondary cell walls only occur when the cell has stopped growing.</p> Signup and view all the answers

What properties does lignin provide?

<p>Strength, rigidity, also it is hydrophobic and will therefore prevent water coming into the cell.</p> Signup and view all the answers

How does the plant cell work around the water-blocking properties of the secondary cell wall?

<p>Use of plasmodesmata to transfer water-soluble substances.</p> Signup and view all the answers

What are plasmodesmata?

<p>Channels between plant cells, allowing free exchange of small molecules. The plasma membrane is continuous through, and endoplasmic reticulum can also extend through.</p> Signup and view all the answers

What is a potential disadvantage of plasmodesmata?

<p>Viruses can move cell to cell via these pathways.</p> Signup and view all the answers

What are the two phases of the cell wall?

<p>Crystalline microfibrillar phase, non-crystalline matrix, and a network of extensins.</p> Signup and view all the answers

Study Notes

Plant Cell Walls Overview

  • Major component of plant cell walls is cellulose, providing structural support.
  • Middle lamellae serve as a substance between adjacent plant cells, facilitating adhesion.

Structure of the Cell Wall

  • Primary cell wall consists of cellulose microfibrils, pectin, hemicellulose, and soluble proteins, contributing to flexibility and strength.
  • Secondary cell walls are thicker, formed after cell growth and contain lignin, which adds durability and rigidity.

Functions of the Cell Wall

  • Provides overall structure and shapes plant cells, influencing morphology.
  • Protects against pathogens and prevents excessive water uptake, enhancing cell survival.

Expansion and Growth

  • Plant cells can expand uniformly in all directions or preferentially along a specific axis, increasing cell length.

Protective Mechanism

  • Rigidity of the cell wall acts as a barrier against physical damage and biological threats.
  • Infected cells can secrete protective chemicals via cell walls to mitigate neighboring infection spread.

Lignin and Its Role

  • Lignin contributes strength and rigidity to the secondary cell wall and creates a hydrophobic barrier to water, limiting fluid intake.

Water Movement

  • Plasmodesmata are microscopic channels between plant cells allowing for the passage of water-soluble substances, bypassing the hydrophobic nature of secondary walls.

Communication and Vulnerability

  • Plasmodesmata's continuous plasma membrane and extending endoplasmic reticulum enable rapid molecular exchange.
  • Viruses exploit plasmodesmata to spread between plant cells, posing a risk to overall plant health.

Cell Wall Composition

  • The cell wall consists of two primary phases: crystalline microfibrillar phase and a non-crystalline matrix, combined with extensin networks for structural integrity.

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Description

Explore the structure, functions, and significance of plant cell walls in this quiz. Learn about the composition, roles in plant growth, and protective mechanisms that enhance cellular integrity. Test your knowledge on how these structures contribute to overall plant health.

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