<< Chapter < Page Chapter >> Page >
This illustration shows two plant cells side-by-side. A gap in the cell wall, a plasmodesma, allows fluid and small molecules to pass from the cytoplasm of one cell to the cytoplasm of the other.
A plasmodesma is a channel between the cell walls of two adjacent plant cells. Plasmodesmata allow materials to pass from the cytoplasm of one plant cell to the cytoplasm of an adjacent cell.

Tight junctions

A tight junction    is a watertight seal between two adjacent animal cells ( [link] ). The cells are held tightly against each other by proteins (predominantly two proteins called claudins and occludins).

This illustration shows two cell membranes joined together by a matrix of tight junctions.
Tight junctions form watertight connections between adjacent animal cells. Proteins create tight junction adherence. (credit: modification of work by Mariana Ruiz Villareal)

This tight adherence prevents materials from leaking between the cells; tight junctions are typically found in epithelial tissues that line internal organs and cavities, and comprise most of the skin. For example, the tight junctions of the epithelial cells lining your urinary bladder prevent urine from leaking out into the extracellular space.

Desmosomes

Also found only in animal cells are desmosomes , which act like spot welds between adjacent epithelial cells ( [link] ). Short proteins called cadherins in the plasma membrane connect to intermediate filaments to create desmosomes. The cadherins join two adjacent cells together and maintain the cells in a sheet-like formation in organs and tissues that stretch, like the skin, heart, and muscles.

This illustration shows two cells fused together by a desmosome. Cadherins extend from each cell and join the two cells together. Intermediate filaments connect to cadherins on the inside of the cell.
A desmosome forms a very strong spot weld between cells. It is created by the linkage of cadherins and intermediate filaments. (credit: modification of work by Mariana Ruiz Villareal)

Gap junctions

Gap junctions in animal cells are like plasmodesmata in plant cells in that they are channels between adjacent cells that allow for the transport of ions, nutrients, and other substances that enable cells to communicate ( [link] ). Structurally, however, gap junctions and plasmodesmata differ.

This illustration shows two cells joined together with protein pores called gap junctions that allow water and small molecules to pass through.
A gap junction is a protein-lined pore that allows water and small molecules to pass between adjacent animal cells. (credit: modification of work by Mariana Ruiz Villareal)

Gap junctions develop when a set of six proteins (called connexins) in the plasma membrane arrange themselves in an elongated donut-like configuration called a connexon. When the pores (“doughnut holes”) of connexons in adjacent animal cells align, a channel between the two cells forms. Gap junctions are particularly important in cardiac muscle: The electrical signal for the muscle to contract is passed efficiently through gap junctions, allowing the heart muscle cells to contract in tandem.

To conduct a virtual microscopy lab and review the parts of a cell, work through the steps of this interactive assignment .

Section summary

Animal cells communicate via their extracellular matrices and are connected to each other via tight junctions, desmosomes, and gap junctions. Plant cells are connected and communicate with each other via plasmodesmata.

When protein receptors on the surface of the plasma membrane of an animal cell bind to a substance in the extracellular matrix, a chain of reactions begins that changes activities taking place within the cell. Plasmodesmata are channels between adjacent plant cells, while gap junctions are channels between adjacent animal cells. However, their structures are quite different. A tight junction is a watertight seal between two adjacent cells, while a desmosome acts like a spot weld.

Questions & Answers

wat is Metamorphosis
Lawal Reply
when the chromosomes aling in the middle during mitosis
Lissette
what is biochemistry
EVANS Reply
Is talking about the little study out of chemistry
LEKAN
Is talking about the little study out of chemistry
LEKAN
How many cells does a human being have?
Awamalego Reply
How many cells does human being have?
Karikari
How many cells does human being have?
Karikari
countless cells
Imamkasim
what is the function of a skeleton
Julien Reply
it supports and gives the appearance of the body.
lo
mandle experiment point
Sarpz Reply
what is the mean of biology
chiluba
In a lay man definition biology talks about life as a whole
VICTOR
the study of living organisms
the study of the structure, function, and origin of living organisms
biology has many branches. Botany (the study of plants) , evolution,. Ecology (how animals interact amongst each other. the study the habitat of an animal and try to determine as well as find strategies to prevent a species from going extinct.
is simply the study of life
Namuli
hello
Namuli
what is a specicide
Twinkl Reply
why are mosquitoes primary and secondary consumers
Twinkl
what are the structures found in all viruses
Twinkl
how does vaccinating a woman prevent her baby from getting the illness?
Twinkl
how does selective breeding increase crop size
Twinkl
wat is an animal cell
Monicah Reply
what is deer
Khansawu Reply
breathing in reptiles
sam Reply
which molecules binds to the active site of an enzyme
Ghulam Reply
human
Haggai
please remind me
Bafaa
please I do not no
Bafaa
please remind me
Bafaa
please I do not no
Bafaa
please remind me
Bafaa
what is nutrients
Patrick Reply
nutrients is substance which body use in terms of need
Haggai
yes..
Abdullahi
can I join?
Osei
substance that provides nourishment essential for the maintenance of life and for growth.
umar
right same answer as you Umar
Namuli
please remind me
Namuli
Any material that provide essential components for cell metabolisms is nutrient
Mahmood
what are the types of skeleton
Tanyi Reply
endo skeleton and exo skeleton
Faith
or types of skeletons There is exo skeleton found in class insecta Exo skeleton found in phylum chordata and lastly hydrostatic skeleton found mainly in earth worms
Daniel
and hydrostatic skeleton
Godbless
bronah
Kapoko
endo, exo and hydrostatic skeleton
Mico
what is life?
Jerson Reply
life is when any living thing breath or respirate.
Lucky
I want to join
Patrick
me too
Favour
me two
Monday
me too
Bengazy
me too
Maggie
I here
Yahaya
Does anybody knows another biology app that brings good understand
Lucky
give an example of a phylum where all members have open circulatory
Omoro Reply
anthropoda
Daniel
phylum Anthropoda
Daniel
how do u change the unit of temperature from degree celsius to degree Fahrenheit
Maggie
what are beneficial effects in industrial
Nnamani Reply
create employment
ibrahim
provide food
ibrahim
pollution
ibrahim
dirty the environment
ibrahim
pollution and lack of knowledge about how to manage waste
Alex

Get the best Biology course in your pocket!





Source:  OpenStax, Biology. OpenStax CNX. Feb 29, 2016 Download for free at http://cnx.org/content/col11448/1.10
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Biology' conversation and receive update notifications?

Ask