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BossMan300 BossMan300
wrote...
Posts: 40
Rep: 1 0
9 years ago
The pH inside the cell is less than that outside of the cell.
From my perspective, the inside of the cell is proton rich and would be great at accepting electrons.  I am confused as to what molecules gain electrons (reduction is gain) within the cell?
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9 Replies
Replies
wrote...
Educator
9 years ago
The pH inside the cell is less than that outside of the cell.

What's the reason for this? Is it only because the inside is proton-rich, as you added? I think a better question here is why is the inside more acidic than the outside.
BossMan300 Author
wrote...
9 years ago
"Intracellular pH is around 6.8 due to acid production."
Several other factors were listed that can effect intracellular pH including:
metabolic acid production, leakage of acid across plasma and organelle membranes and membrane transport processes

en.wikipedia.org/wiki/Intracellular_pH

"The normal extracellular pH is 7.4±0.1."

en.wikipedia.org/wiki/Intracellular_pH
 C. Deutsch; J. S. Taylor; D. F. Wilson (December 1982). "Regulation of intracellular pH by human peripheral blood lymphocytes as measured by 19F NMR". Proc. Natl. Acad. Sci. U.S.A. 79 (24): 7944–7948. doi:10.1073/pnas.79.24.7944. PMC 347466. Retrieved 2014-08-01.

Post Merge: 9 years ago

[/quote]
why is the inside more acidic than the outside.
[/quote]
wrote...
Educator
9 years ago
NAD+ gets reduced, so does FADH. Too many molecules to list.

Thanks for the answer btw.
BossMan300 Author
wrote...
9 years ago Edited: 9 years ago, BossMan300
In general in life I like people who have solutions not problems.  So I will propose a solution that I thought of.  Please provide feedback.

Hydrogen's oxidation number is 0 when bonded with another hydrogen.
Hydrogen's oxidation number is +1 often when bonded with another molecule in biochemistry.

When two hydrogen's are removed from their parent molecule and they recombine they are going from an oxidation number of +1 to 0.  The hydrogen's have been reduced.  This means that the parent molecules have been oxidized, respectively. 

The extracellular space is considered an oxidizing environment.
Why?
I stated that the extracellular space is more basic (higher pH).

For the parent molecule proton hosting molecule to be oxidized.  The hydrogen must be reduced.
This process is called deprotonation.  Where is deprotonation most likely to occur?  An environment with a higher pH.  The extracellular space is able to reduce the hydrogen, causing the parent molecule to be oxidized.  Thus accomplishing oxidation of the larger molecule. 
 
Similar logic can be applied to the intracellular space regarding it being a reducing environment.

What do you think internet world.  I have taken no biochemistry in college. 
Post Merge: 9 years ago

any opinions on what Ca stands for at:
https://www.bio.cmu.edu/courses/03231/LecF04/Lec05/aa_titration.pdf
it is attached to the amino acids.

What does Ca stand for in this amino acid picture, I don't think its circa or ..
Answer accepted by topic starter
rsbrsb
wrote...
Posts: 234
9 years ago
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BossMan300 Author
wrote...
9 years ago Edited: 9 years ago, BossMan300
Your're right. Hydrogen would have a negative charge when with metal hydrides.
In the case of H2 I think the charge is neutral (0) and in cysteine R-S-H I believe H has an oxidation number of +1.  Since you said, "The oxidation state of hydrogen is +1 in its compounds, except for metal hydrides."  I take it you agree.  Is the way that I tried to explain why the intracellular/extracellular space is an reducing/oxidizing environment correct?
Thanks for your reply.
wrote...
Educator
9 years ago
In the case of H2 I think the charge is neutral (0) and in cysteine R-S-H I believe H has an oxidation number of +1.

First statement is true, not sure about the second though. Because of hydrophobic nature of Cysteine, it generally found on the interior of proteins. Sometimes Cysteine can be ionized to form the thiolate anion but very less found on surface of proteins.



The presence of thiol group make the molecule to susceptible for various enzymatic reactions in which thiol group act as nucleophile and involve in disulphide bond.

BossMan300 Author
wrote...
9 years ago Edited: 9 years ago, BossMan300
http://www.bio.davidson.edu/genomics/jmol/aata
In the case of H2 I think the charge is neutral (0) and in cysteine R-S-H I believe H has an oxidation number of +1.

Because of hydrophobic nature of Cysteine,



The presence of thiol group make the molecule to susceptible for various enzymatic reactions in which thiol group act as nucleophile and involve in disulphide bond.


ble.html
Cysteine is hydrophilic
Post Merge: 9 years ago

http://www.bio.davidson.edu/genomics/jmol/aatable.html
http://www.proteinstructures.com/Structure/Structure/amino-acids.html
wrote...
Educator
9 years ago
Some sources say otherwise. This one dumbs it down Face with Stuck-out Tongue

[box title=Is cysteine hydrophilic or hydrophobic?]
What you need to understand is that a molecule being polar and nonpolar is not white and black. There is a huge grey area. Think of polarity as a scale of 1-10. If something is very polar (1) then it is hydrophilic. If a molecule is nonpolar (10) it is hydrophobic. However due to the molecular structure of cysteine it contain both polar and nonpolar attributes, meaning it can be both hydrophilic and hydrophobic.

That being said, on the hydrophobicity scale (how hydrophilic or hydrophobic a molecule is) cysteine ranks more towards the hydrophobic side.[/box]
Source  https://answers.yahoo.com/question/index?qid=20130302092913AA6nCNb
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