Cell surface junctions, Biology

Assignment Help:

CELL SURFACE JUNCTIONS

(1)      Desmosomes (Maculae adherence) - Thickened circular areas on P.M. of adjacent cells with radiating fibrils in cytoplasm. These fibrils called tonofibrils. Desmosomes generally occurs in epithelial cells and provide cell adhesion. Desmosomes without tonofibrils are called terminal bars.

(2)      Tight junction or Zona occludence - outer most layers of two P.M. at the site of attachment fuse completely.

Fused membrane reveals a 5- layered structure. Permeability of ions is more at tight junction. Tight junction occurs in nerve tissue at synapses. (electrical synapse)

(3)      Gap junction or Nexus - Fine protein channel (connexon) join two P.M of adjacent cells. Exchange of ions between cells may takes place by protein channels. Desmosomes, Tight junction and Gap junction occurs in animal cell.

(4)      Plasmodesmata - Name proposed by strassburger. Cytoplasmic connection bet. Two adjacent cells through pores in cell wall and cell membrane. Plasmodesmata are characteristic of multi-cellular plants and they maintain continuity of cytoplasm between adjacent cells. Plasmodesmata often contain an expanded E.R. termed as desmotubule.

1124_modifications of cell membrane.png


Related Discussions:- Cell surface junctions

Write the meaning of hypoglycemia, Q. Write the meaning of Hypoglycemia? ...

Q. Write the meaning of Hypoglycemia? Hypoglycemia is a Greek term: hypo -meaning less; glyc - means sweet; and emia - means "of the blood". It is a condition in which less th

What is an advantage of using proteins, Plants use proteins, lipids and sta...

Plants use proteins, lipids and starch as seed storage compounds. What is an advantage of using proteins as a storage compound that are not afforded by lipids or starch?

Determine the term - origin of life on earth, Based on your reading of the ...

Based on your reading of the article "Origin of Life on Earth" which of the following is a false statement regarding how life developed? A. As proteins are needed for the repli

Define the future challenges of spatial processes, Define the Future challe...

Define the Future challenges of spatial processes? Understanding the dynamics of stochastic spatial systems, systems with a multitude of spatial scales, and systems along with

How are the fruits formed, How are the fruits formed? The fecundation i...

How are the fruits formed? The fecundation is in angiosperms triggers the release of hormones that act upon the ovaries. The ovary wall after that it develops into a fruit that

Taxonomy, Agroup of realated genera are classified as-?

Agroup of realated genera are classified as-?

List the stages of process of behaviour change, Q. List the stages of proce...

Q. List the stages of process of behaviour change? Stages of behaviour change process: · Unawareness · Awareness · Acquiring knowledge · Motivation · Trial

Explain the primary treatment for managing food allergies, Explain the Prim...

Explain the Primary Treatment for Managing Food Allergies? The primary treatment for managing food allergies is eliminating the offending food or foods. In fact, non-pharmacolo

Define requirements of sodium during pregnancy period, Define requirements ...

Define requirements of Sodium during pregnancy period? As you know, sodium plays a role in fluid balance. Sodium metabolism is altered during pregnancy under the stimulus of a

Excitation of heart - circulation, Excitation of Heart - Circulation T...

Excitation of Heart - Circulation The heart has an inherent capacity to contract rhythmically without any external stimulus. Proof of this is obtained when we see that the hea

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