First Unit 3 SAC?

[peterpan101]

so this and many other pracs
http://www.123helpme.com/view.asp?id=62278
are wrong about glucose being able to travel across the membrane ?

[Yacoubb]

so this and many other pracs
http://www.123helpme.com/view.asp?id=62278
are wrong about glucose being able to travel across the membrane ?

I never said glucose does not travel across the membrane... and I cannot even see the link because it isn't loading... do care to elaborate?

[peterpan101]

Glucose is transported across the membrane via the protein channel in Facilitated Diffusion.

so it cannot travel across dialysis? 

heres another link
http://www.scienceforums.net/topic/35861-can-glucose-molecules-pass-through-a-semi-permeable-dialysis-tubing/
http://dtc.pima.edu/blc/181/Lessons/L5/5step4/5step4page1.htm

:/ im soo confused

[Yacoubb]

so it cannot travel across dialysis? 

heres another link
http://www.scienceforums.net/topic/35861-can-glucose-molecules-pass-through-a-semi-permeable-dialysis-tubing/
http://dtc.pima.edu/blc/181/Lessons/L5/5step4/5step4page1.htm

:/ im soo confused

Is the dialysis tube made of a phospho-lipid bilayer? It isn't; hence, glucose is able to diffuaacross the dialysis tube, which is also, mind you, designed for substances including glucose to diffuse across.

[peterpan101]

Is the dialysis tube made of a phospho-lipid bilayer? It isn't; hence, glucose is able to diffuaacross the dialysis tube, which is also, mind you, designed for substances including glucose to diffuse across.

its made of cellulose.

[Yacoubb]

its made of cellulose.

Yeah well that explains why glucose is able to pass through the dialysis tube - however, in a real life situation, glucose cannot dissolve through the lipid bi-layer, and is thus only able to pass the membrane via facilitated diffusion through the protein channel. To be honest, I haven't worked with dialysis tubes a lot because we didn't use them in 1+2 Biol for me. Just don't assume that the effects of the dialysis tube bag would be the same in a normal cell.

[peterpan101]

in the prac we are doing we are testing
Glucose
Starch
Iodine
Water
Why are we testing these?

[Bad Student]

in the prac we are doing we are testing
Glucose
Starch
Iodine
Water
Why are we testing these?

I think you're going to be investigating the effect of glucose and starch on osmosis in your prac.

The glucose will be dissolved in the water. This will probably create an imbalance between the concentration of water on each side of the membrane and cause osmosis to occur.

The starch will be added to the water. However, it won't have any effect on the concentration of water because it doesn't dissolve.  Iodine is used to test for the presence of starch.

[Smiley_]

I think you're going to be investigating the effect of glucose and starch on osmosis in your prac.

The glucose will be dissolved in the water. This will probably create an imbalance between the concentration of water on each side of the membrane and cause osmosis to occur.

The starch will be added to the water. However, it won't have any effect on the concentration of water because it doesn't dissolve.  Iodine is used to test for the presence of starch.

is it also because  these things are required for a cell so this will help with your understanding ?

[Bad Student]

is it also because  these things are required for a cell so this will help with your understanding ?

Yes

[Yacoubb]

You're affecting the concentration of the solution and almost inducing osmosis to occur

[peterpan101]

in the prac we are doing we are testing
Glucose
Starch
Iodine
Water
Why are we testing these?

sorry I worded that wrong, i wanted to ask 3 reasons for using these substances in this experiment to explore movement across a cellulose semi perm membrane ?
thanks

[katerina]

Woohoo alright do you recall what results you took? I mean, did you take down results of the size of the potato cube, and compare the size of the cube in the hypertonic solution compared to the hypotonic solution?! I'd probably PM you closer to the date of my SAC. Thank you!!

It'll most likely be up to you to decide whether the solution was hypertonic or hypotonic, and it'll be up to you to discuss WHY (remember to always refer to your observations as proof).

Regardless of what material you use (I used an egg) the concepts will still be the same. Osmosis. What is able to pass through the membrane and how. And what hypertonic/hypotonic solutations are!

Goodluck

[peterpan101]

water only travel by diffusion doesn't it?

[Yacoubb]

water only travel by diffusion doesn't it?

The movement of water molecules across the semi-permeable plasma membrane from an area of low solute concentration to an area of high solute concentration is called osmosis. However, this is not the completely ONLY means by which water travels across the membrane. Some protein channels called aquaporins allow the facilitated diffusion/channel-mediated transport of water molecules across the plasma membrane.

Mainly however, osmosis is the path taken by water molecules, that want to fit in with the cool solutes and ditch the poor, innocent cell cool analogy hey?