Go Back   Science Forums Biology Forum Molecular Biology Forum Physics Chemistry Forum > Molecular Research Topics Forum > Histology Forum
Register Search Today's Posts Mark Forums Read

Histology Forum Histology Forum. Talk, discuss and post questions on general histology methods including tissue processing, embedding tissues, sectioning, special staining, enzyme staining and silver staining of samples.


Question about simple cytoplasmic staining.

Question about simple cytoplasmic staining. - Histology Forum

Question about simple cytoplasmic staining. - Histology Forum. Talk, discuss and post questions on general histology methods including tissue processing, embedding tissues, sectioning, special staining, enzyme staining and silver staining of samples.


Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 03-18-2011, 02:43 AM
Pipette Filler
Points: 54, Level: 1 Points: 54, Level: 1 Points: 54, Level: 1
Activity: 0% Activity: 0% Activity: 0%
 
Join Date: Mar 2011
Posts: 1
Thanks: 0
Thanked 0 Times in 0 Posts
Default Question about simple cytoplasmic staining.



Doing some studying from Carson and Hladik's Histotechnology 3rd edition. So if anyone is familiar with this text, I'd would greatly appreciate some help. I believe 2nd edition is very similar as well.

On page 107, second column, Cytoplasmic Staining....there is FIGURE 6.1 which depicts the structural formula for a simple amino acid and the effect of its isoelectric point (pH 6). I'm confused why the amino acid is listed as "basic (+)" with a lower pH and "acidic (-)" at a higher pH. A simple definition of acid (Lewis or Bronstead-Lowry?) says that an acid is any substance that can donate a H+ ion. This seems to be the case for the amino acid at the lower pH, since the amino and carboxyl groups are both +, meaning it would very readily react with a base, which is a substance that accepts H+. So why the reverse of the classifications in the figure?

The next page (108, final paragraph) even says:
Quote:
...below the IEP or below pH 6, the net charge on nonnuclear proteins is positive and the attraction is for anionic dyes.
In other words, dyes with a - charge, which, by definition, would readily accept H+, thus defining them as basic dyes. Continuing...
Quote:
Above the IEP, the net charge is negative and the attraction is for cationic dyes.
Or dyes with a + charge (insert definition of acid here), thus making them acidic dyes.
Quote:
Substances attracting basic dyes are "basophilic". Substances attracting acidic dyes are "acidophilic".
So, adding up what we've covered so far...basophils would be acids and acidophils would be bases. The book then uses Eosin as an example of a negative dye. Skipping down the paragraph, we have this:
Quote:
Although eosin is negatively charged [...] if the pH of the dye solution is dropped too low, the -COO group of eosin will combine with hydrogen [I'm assuming from the acid that's been used to lower the pH] and the result is the free acid, uncharged form of eosin.
The fact that too low of a pH causes the negatively charged eosin's -COO group to react with H would tell us that eosin is a basic dye and the point on the tissue with the amino acids present are the acidic constituent that reacts with it (eosin).

So again, in FIGURE 6.1 on 107, why is the amino acid listed as "basic (+)" at the lower pH and "acidic (-)" at the higher pH?

Thanks for any help. Sorry I don't have a picture to post.

Last edited by GrimmHatter; 03-19-2011 at 02:58 AM.
Reply With Quote
Reply

Tags
cytoplasmic , question , simple , staining


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
A simple excel question liseaso BioStatistics Forum 2 04-15-2010 04:18 PM
definitions for physics, a simple question for a simple mind Aaron Physics Forum 8 09-11-2007 11:02 PM
definitions for physics, a simple question for a simple mind Aaron Physics Forum 0 09-10-2007 11:41 AM
Simple Paradox question docdan Physics Forum 17 11-10-2005 10:06 PM
simple quantum mechanics exam question Chris Physics Forum 1 01-15-2005 07:53 PM


All times are GMT. The time now is 02:30 AM.


Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright 2005 - 2012 Molecular Station | All Rights Reserved
Page generated in 0.11887 seconds with 16 queries