Types of cell wall, Biology

Assignment Help:

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


Related Discussions:- Types of cell wall

How is fecundation done in insects, Q. How is fecundation done in insects (...

Q. How is fecundation done in insects (internal or external)? Is there copulation between insects? Fecundation in insects is internal, with copulation.

Effects of plant growth regulators on development, Effects of Plant Growth ...

Effects of Plant Growth Regulators on Development Like animals plants require input of energy from the outside environment to sustain growth and development. But unlike anim

What is surgical therapy, Surgical Therapy The clinician may use a surg...

Surgical Therapy The clinician may use a surgical approach when non-surgical therapies are not indicated or are unsuccessful. The surgical techniques are modified from those

Pregnancy, What are the physiological changes during pregnancy

What are the physiological changes during pregnancy

What is phenotypical proportion, Considering hybridization in a given trait...

Considering hybridization in a given trait like the color of the hair of a mammalian species (white/black) conditioned by a pair of different alleles under complete dominance (blac

Define a protein amino acid sequence, Protein structure is determined solel...

Protein structure is determined solely by a protein amino acid sequence. Should a genetically engineered protein in which the order of all amino acids is reversed therefore have th

Define methods of prevention and control of anaemia, Define methods of prev...

Define methods of prevention and control of anaemia? The available methods of prevention and control of anaemia are: Supplementation Food fortification Dietary

What is pancreas , What is Pancreas ? The pancreas lies in the abdomina...

What is Pancreas ? The pancreas lies in the abdominal cavity in a loop between the stomach and small intestine. The pancreas consists of two major types of cells: those produci

Determine the benedict test, Determine the Benedict's Test Glucose in u...

Determine the Benedict's Test Glucose in urine is detected by Benedict's method and the test is known as Benedict's test. This test is used to detect glucose in urine (Glycosur

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd