Types of cell wall, Biology

TYPES OF CELL WALL

Cell wall differentiated into the following layers :

1. Primary Cell Wall       2. Secondary Cell wall             3. Tertiary Cell wall

1.       PRIMARY CELL WALL (10 CELL WALL)

  • The first formed cell wall is known as primary cell wall, laid inner to the middle lamella.
  • The primary cell was is comparatively thin and permeable.
  • It consists of hemicellulose 50%, cellulose 20%, lipid 20%, Protein 1-2%, water 60%
  • Macrofibrils of cellulose are randomly distributed.
  • Found in all types of plant cell (meristematic & soft parenchymatous tissues like mesophyll, cortex, pith, fruit)
  • Microfibril are loose wavy & short. Lignin, Pectin is also present.
  • The primary cell wall of the yeast & the fungi is composed of the chitin.

2.       SECONDARY CELL WALL (20 CELL WALL)

  • The secondary cell wall is thick, permeable & lies near the plasma membrane or the tertiary cell wall.
  • It is composed of 3 layers S1, S& S3 (S2= thickest and S3 thinnest layer)
  • Chemically the secondary cell wall is composed of compactely arrange macrofibrils of the cellulose, hemicellulose, pectin & lignin. Hemicellulose 25%, cellulose 20-40%, Lipid - protein = negligible amount, Hydration = 30%
  • Formed by apposition / accretion (growth occur due to accretion) intussusception
  • To have a uniform thickness Intussusception method is better than apposition.
  • Thickness 3-10 mm, uniform thickness absent.
  • At places the thickning is absent it form pits.
  • It collenchyma it provides elasticity & allow for limited growth.
  • Macrofibrils arranged in a regular pattern (parallel to long axis)
  • Present in Sclerenchyma, Vessels, Tracheids. Absent in Meristem.
  • Thickening is of purely cellulose in collenchyma cells, cotton fibres, flax fibres.

3.       TERTIARY CELL WALL

  • In certain plant cells another cell wall found beneath the secondary cell wall which is known as tertiary cell wall.
  • It consists of xylan and hemicellulose. (Xylan is the polymer of xylulose.)
  • Tertiary cell wall found in tracheids of gymnosperms (Tension wood).

1005_cell wall.png

Posted Date: 10/5/2012 4:40:32 AM | Location : United States







Related Discussions:- Types of cell wall, Assignment Help, Ask Question on Types of cell wall, Get Answer, Expert's Help, Types of cell wall Discussions

Write discussion on Types of cell wall
Your posts are moderated
Related Questions
According to the chemistry concept the existence of different kinds of crystal of the same chemical compound is known as polymorphism

Define Conjunctival Xerosis - Micronutrient Deficiencies? Conjunctiva in nonnal children is bright white, smooth and glistening. Conjunctival xerosis is characterized by drynes

What are the Materials required for Radiographic 1. Alginate impression material. 2. Silicone separating spray/ petroleum jelly 3. Autopolymerizing PMMA (Clear)

Diastolic dysfunction is  responsible for one third of cases of heart  failure alone and rest two  third of cases in  combination with systolic dysfunction. Diastolic dysfunction c

Q. Cnidarians and Poriferans do not have excretory systems. Do platyhelminthes have an excretory system? Platyhelminthes have a primitive excretory system made of flame cells

define and explain Water vascular system with podia and tube-feet madreporite mostly present

Chief Complaint and Patient's Expectations It is extremely vital to know what the patient really wants. 1. The chief complaint should be recorded in patient's own words as f

What do you understand by Coelenteron? The name given to internal cavity of the cnidarians. This is an incomplete gut with just one opening, the mouth. Food to be digested and

Endocrine System The nervous system brings about integration and co-ordination of several activities of the animal. The afferent stimuli from several sense organs are brought

Question 1 Write a short note on the following- Theory of clonal selection Interferons Super antigens Helper T cells Auto immunity Active Immunization