Water concentration in cells

[jnicko989]

Hi,

Sorry, I am just looking for an answer as to why the concentration of water has to be maintained within cells? It's a dot point and I have a few answers, but my teacher said I wasn't addressing the question clearly enough when I talked about it being to concentrated or too dilute (and metabolic reactions not being able to occur as a result), what else would I need to add in order to bring the dot point up to scratch? I've read summaries and stuff but honestly I just don't get it.

Any help would be great,
Jeremiah.

[naomisirmai]

Hey Jeremiah! It seems from your post that you have a good general idea of the answer! I think by adding a bit of detail, and a few key words, you can meet your teacher's requirements.

I'd say something along the lines of the fact enzymes (the biological catalysts that catalyse the reactions of metabolism) work best at their optimal conditions - including when water concentrations are optimal - especially given that metabolic reactions occur in solution. Thus, any variation from ideal water concentration will negatively impact metabolism.

If cells aren't at their isotonic state - where the solute concentration is the same both inside and out - they'll either swell up with too much water (if they are in a hypotonic - not salty enough - solution) or shrivel and become 'crenated' with not enough water (if they are in a hypertonic - too salty - solution). They can't work well in these conditions and their ability to perform reactions of metabolism be impeded.

Hopefully this answers your question!
Naomi

[jnicko989]

Oh, that makes sense - I forgot about the need to talk about enzymes. Thank you so much.

If they become hypotonic, I think the teacher mentioned something about them bursting? Is that right or not? It's kind of a vague recollection so it may have been something else.

[naomisirmai]

Yep that's exactly right! In a super hypotonic environment, cells can burst. Here's a video that shows it happening: https://www.youtube.com/watch?v=OYoaLzobQmk

[jnicko989]

Oh, thank you, that video was very helpful - if we get a question talking about the concentration of water in cells, would it be wise to use this video as an example? Just talking about how the erythrocytes and leukocytes burst when subjected to a hypotonic solution? (or erythrocytes losing haemoglobin as opposed to bursting)

[naomisirmai]

Oh, thank you, that video was very helpful - if we get a question talking about the concentration of water in cells, would it be wise to use this video as an example? Just talking about how the erythrocytes and leukocytes burst when subjected to a hypotonic solution? (or erythrocytes losing haemoglobin as opposed to bursting)

Hmm I'd structure an answer like this;
- cells should be at their 'isotonic' state. this is because the enzymes vital for metabolism work most efficiently when they are at their optimal conditions.
- when cells are in hypotonic solutions - where the ion concentration inside the cell is greater than outside - they can swell and burst (inefficient for enzyme activity and metabolism)
- when cells are in hypertonic solutions - where the ion concentration outside the cell is greater than inside - they can shrivel and become crenated (inefficient for enzyme activity and metabolism).

I can't imagine getting a question worth more than 3 marks about this minor dot point.