Name: plant cell wall support: cellulose and pectin
Uploaded: 2023-04-30T11:56:41.000Z
Duration: 1 min 15 s
Channel: JoVE

K12 Standards

Florida Department of Education

High School

Life Science

SC.912.L.18

SC.912.L.18.2

Cellulose and Pectic Polysaccharides

New plant cells have a primary cell wall and middle lamella, comprising cellulose fibers embedded in a gel-like matrix containing polysaccharides and proteins.
Cellulose is a long, linear chain of glucose. Around sixteen cellulose molecules are connected in parallel by hydrogen bonds, forming rod-like microfibrils that impart rigidity and resist tensile forces.
Branched polysaccharides, such as hemicellulose, cross-link microfibrils into a structural network that allows expansion during cell growth.
The cross-linked cellulose layers are suspended in a pectin matrix.
Pectins are polysaccharides containing negatively charged galacturonic acid units surrounded by cations and water molecules. Calcium ions crosslink pectins into a semirigid gel that cements the walls of adjacent cells.
As a plant cell matures, a secondary cell wall can form between the primary cell wall and the plasma membrane. It contains hardening polymers such as lignin that provide the protection and support required for water movement.

cellulose and pectic polysaccharides

&#160;Every plant cell has a cell wall that protects the cell, provides structural support, and gives the cell shape. Cellulose, the main structural component of the plant cell wall, makes up over 30% of plant matter. It is the most abundant organic compound on earth.&#160; Cellulose is an unbranched polysaccharide composed of linear chains of glucose molecules linked by &#946; (1&#8594;4) glycosidic bonds.
As a cell matures, its cell wall specializes according to its type. For example, the parenchyma cells of leaves possess only a thin, primary cell wall. Collenchyma and sclerenchyma cells, on the other hand, mainly occur in the outer layers of a plant&#39;s stems and leaves. These cells provide strength and support by partially thickening their primary cell wall or depositing a secondary cell wall. Some plants, such as trees and grasses, deposit a secondary cell wall around mature cells. Secondary cell walls typically contain three distinct layers: in each layer, the cellulose microfibrils are organized in different orientations.
The cell wall contains other polysaccharides, such as pectin. Pectic polysaccharides are heteropolysaccharides that predominantly have a galacturonic acid sugar backbone with acid sugar and neutral sugar side chains. During cell growth and expansion, pectic polysaccharides are deposited in the middle lamella, followed by the primary and secondary cell walls. They are crucial in wall hydration and cell-cell adhesion. They also influence wall porosity, regulate ion transport, and help in the morphogenesis of plants by impacting the enzymes in the cell wall and their water-holding capacity.
Homogalacturonan, the most prominent type of pectin, accounts for around 60% of total pectin in cell walls.
Adapted from openstax biology 2e

&#160;Every plant cell has a cell wall that protects the cell, provides structural support, and gives the cell shape. Cellulose, the main structural ...

Education

JoVE Core

Cell Biology

Unit 1

Plant Cell Structure and Organization

KEY TERMS AND CONCEPTS

plant cell wall support: cellulose and pectin

Plant cell walls use cellulose and pectic polysaccharides to give cells shape, support, and protection. Cellulose is the main structural part of the plant cell wall and makes up more than 30% of plant matter. It is also the most abundant organic compound on Earth.

Cellulose is an unbranched polysaccharide. It is made of long, linear chains of glucose joined by β(1→4) glycosidic bonds. As plant cells mature, their walls become specialized for cell type and function.

Parenchyma cells in leaves usually have only a thin primary cell wall. Collenchyma and sclerenchyma cells are often found in the outer layers of stems and leaves. These cells help strengthen the plant by thickening the primary wall or by adding a secondary cell wall. In some plants, such as trees and grasses, mature cells develop a secondary wall with three distinct layers. In each layer, the cellulose microfibrils point in different directions.

Plant cell walls also contain pectin, a group of pectic polysaccharides. These are heteropolysaccharides with a galacturonic acid backbone and acid sugar and neutral sugar side chains. During cell growth and expansion, pectic polysaccharides are deposited in the middle lamella, then in the primary and secondary cell walls. They help walls hold water, support cell-cell adhesion, affect wall porosity, regulate ion transport, and assist plant morphogenesis by influencing wall enzymes and water-holding capacity. Homogalacturonan is the most common pectin type and makes up about 60% of total pectin in cell walls.

Plant Cell Wall Support: Cellulose and Pectin

plant-cell-wall-support-cellulose-and-pectin

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Plant Tissue Systems and Growth

Plant tissue systems help plants grow, support themselves, and move materials through their bodies. Plants are multicellular eukaryotes with cells arranged into tissues, tissues that work together to form organs, and organs that work together to form organ systems. Vascular plants have two main organ systems: the shoot system and the root system. The shoot system includes the vegetative parts of the plant, such as leaves and stems, as well as the reproductive parts, which include flowers and...

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Plant cell walls give cells shape, protection, and support. This rigid outer layer helps plants stay upright and keeps cells from bursting when they take in water. During cell division, vesicles carry enzymes, proteins, and glucose molecules to the center of the cell. These vesicles fuse again and again to build a cell plate between the two dividing cells. As the cell plate matures, new polysaccharides are added, and the daughter cells form their new cell walls. Cellulose is the main...

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Plant cell walls use cellulose and pectic polysaccharides to give cells shape, support, and protection. Cellulose is the main structural part of the plant cell wall and makes up more than 30% of plant matter. It is also the most abundant organic compound on Earth. Cellulose is an unbranched polysaccharide. It is made of long, linear chains of glucose joined by β(1→4) glycosidic bonds. As plant cells mature, their walls become specialized for cell type and function. Parenchyma cells in leaves...

role of microtubules in cell wall deposition

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Microtubules Guide Cellulose Alignment

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Plant Cell Walls and Cell-to-Cell Links

Plant cell walls help neighboring cells stay attached. Their rigid walls are built from cell wall polysaccharides that support cell-cell adhesion. In primary cell walls, two connected polysaccharide networks work together: a pectin matrix and a second network made of cellulose and hemicelluloses. Pectins are complex heteropolymers, or polymers made from more than one kind of sugar. They contain mostly negatively charged α-D-glucopyranosyl uronic acid. They also include neutral glycosyl...

key terms and concepts

Learn how cellulose and pectic polysaccharides build plant cell walls, support cell shape, and help with adhesion, water balance, and wall structure.

Plant Cell Wall Support: Cellulose and Pectin | JoVE K12

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SC.912.L.18.8

A. All living things are composed of four basic categories of macromolecules and share the same basic needs for life.

B. Living organisms acquire the energy they need for life processes through various metabolic pathways (primarily photosynthesis and cellular respiration).

C. Chemical reactions in living things follow basic rules of chemistry and are usually regulated by enzymes.

D. The unique chemical properties of carbon and water make life on Earth possible.

Plant Cell Wall Support: Cellulose and Pectin

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