Login

Welcome, Guest. Please login or register.

March 29, 2024, 10:00:22 am

Author Topic: VCE Biology Question Thread  (Read 3571031 times)  Share 

0 Members and 4 Guests are viewing this topic.

vox nihili

  • National Moderator
  • Great Wonder of ATAR Notes
  • *****
  • Posts: 5343
  • Respect: +1447
Re: VCE Biology Question Thread
« Reply #750 on: February 21, 2014, 11:21:52 pm »
0
Got the enzyme prac sac, in about 2 weeks time! Anything I should know prior to it, or will it be straight forward?
Thanks!

Should be pretty straight forward if you know your enzymes
2013-15: BBiomed (Biochemistry and Molecular Biology), UniMelb
2016-20: MD, UniMelb
2019-20: MPH, UniMelb
2021-: GDipBiostat, USyd

RazzMeTazz

  • Victorian
  • Forum Leader
  • ****
  • Posts: 673
  • Respect: 0
Re: VCE Biology Question Thread
« Reply #751 on: February 21, 2014, 11:34:32 pm »
0
If large molecules have trouble diffusing across the plasma membrane, does that mean even if they are large hydrophobic molecules, they will need to partake in facilitated diffusion in order to cross the plasma membrane?


vox nihili

  • National Moderator
  • Great Wonder of ATAR Notes
  • *****
  • Posts: 5343
  • Respect: +1447
Re: VCE Biology Question Thread
« Reply #752 on: February 21, 2014, 11:36:10 pm »
0
If large molecules have trouble diffusing across the plasma membrane, does that mean even if they are large hydrophobic molecules, they will need to partake in facilitated diffusion in order to cross the plasma membrane?

Presumably there'd be a point where they got too big, but they often don't. Hydrophobic molecules can move through the membrane as though it were a sheet of water.
2013-15: BBiomed (Biochemistry and Molecular Biology), UniMelb
2016-20: MD, UniMelb
2019-20: MPH, UniMelb
2021-: GDipBiostat, USyd

RazzMeTazz

  • Victorian
  • Forum Leader
  • ****
  • Posts: 673
  • Respect: 0
Re: VCE Biology Question Thread
« Reply #753 on: February 22, 2014, 11:12:07 am »
0
Are the terms, isotonic, hypertonic and hypotonic strictly limited to talking about Osmosis?

Or can you use it when talking about diffusion as well:

Eg. - There is a net movement of particles from a hypertonic solution ( relatively high solute concentration) to a hypotonic solution (relatively low solute concentration)


nerdmmb

  • Guest
Re: VCE Biology Question Thread
« Reply #754 on: February 22, 2014, 11:39:36 am »
0
Are the terms, isotonic, hypertonic and hypotonic strictly limited to talking about Osmosis?

Or can you use it when talking about diffusion as well:

Eg. - There is a net movement of particles from a hypertonic solution ( relatively high solute concentration) to a hypotonic solution (relatively low solute concentration)

No, the terms isotonic, hypertonic and hypotonic can be used when describing all types of passive and active transport including osmosis.

In your example, I think try to mention that it is along the concentration gradient :)

MM1

  • Victorian
  • Forum Obsessive
  • ***
  • Posts: 213
  • Respect: 0
Re: VCE Biology Question Thread
« Reply #755 on: February 22, 2014, 12:38:19 pm »
0
Are the terms, isotonic, hypertonic and hypotonic strictly limited to talking about Osmosis?

Or can you use it when talking about diffusion as well:

Eg. - There is a net movement of particles from a hypertonic solution ( relatively high solute concentration) to a hypotonic solution (relatively low solute concentration)

They're exclusive to osmosis. Tonicity refers to osmotic pressure so it only relates to solvents. I would only use it for osmosis, not diffusion.

Rishi97

  • Victorian
  • Part of the furniture
  • *****
  • Posts: 1042
  • Respect: +40
  • School: The University of Melbourne
  • School Grad Year: 2014
Re: VCE Biology Question Thread
« Reply #756 on: February 22, 2014, 12:43:21 pm »
0
What can/cannot readily pass through the cell membrane?
Preferably 2-3 sentences.
Thanks ;)
2014: VCE completed
2015-2017: BSc at Melb Uni

DREAM, BELIEVE, ACHIEVE!!!

Chang Feng

  • Victorian
  • Forum Obsessive
  • ***
  • Posts: 218
  • Respect: 0
Re: VCE Biology Question Thread
« Reply #757 on: February 22, 2014, 12:48:39 pm »
+1
I will have a try at this. Non-polar/ uncharged/ small molecules can pass through membrane. Whilst large, charged, polar molecules can not pass through the plasma membrane unless aided by a membrane protein. Don't trust me In just guessing, someone please correct me

Chang Feng

  • Victorian
  • Forum Obsessive
  • ***
  • Posts: 218
  • Respect: 0
Re: VCE Biology Question Thread
« Reply #758 on: February 22, 2014, 12:51:53 pm »
0
Also about enzymes they can change shapes. From listening to podcast, some hormones can bind to enzymes changing their active shape and hence able other molecules to bind to active site or something. I'm not to sure

grannysmith

  • Victorian
  • Part of the furniture
  • *****
  • Posts: 1303
  • Crisp and juicy.
  • Respect: +66
Re: VCE Biology Question Thread
« Reply #759 on: February 22, 2014, 12:54:17 pm »
0
If anyone can clarify the following that would be greatly appreciated :)

Would you say that facilitated diffusion is the passive, net movement of particles from a region of high concentration to a region of low concentration, via transmembrane proteins?
Or do you have to specify carrier/channel proteins?

Also, cholesterol helps stabilise the phospholipid bilayer by maintaining its rigidity at high temperatures, whilst it maintains the cell membrane's fluidity at low temperatures. If it asks for an explanation, I would say that at high temperatures, it decreases the membrane's permeability to polar substances, while it increases the membrane's permeability to polar substances at low temperatures.

Thanks

nerdmmb

  • Guest
Re: VCE Biology Question Thread
« Reply #760 on: February 22, 2014, 01:29:35 pm »
-1
They're exclusive to osmosis. Tonicity refers to osmotic pressure so it only relates to solvents. I would only use it for osmosis, not diffusion.

Do you mean hypertonic, hypotonic and isotonic are restricted to osmosis?
I'm very sure they can be used when describing any form of diffusion. After all, osmosis is a form of diffusion.

grannysmith

  • Victorian
  • Part of the furniture
  • *****
  • Posts: 1303
  • Crisp and juicy.
  • Respect: +66
Re: VCE Biology Question Thread
« Reply #761 on: February 22, 2014, 01:41:30 pm »
+1
Do you mean hypertonic, hypotonic and isotonic are restricted to osmosis?
I'm very sure they can be used when describing any form of diffusion. After all, osmosis is a form of diffusion.

Usually we refer to solutions as being hypertonic, isotonic or hypotonic to another solution. Because of this, I'd say it's mainly referring to osmosis.

MM1

  • Victorian
  • Forum Obsessive
  • ***
  • Posts: 213
  • Respect: 0
Re: VCE Biology Question Thread
« Reply #762 on: February 22, 2014, 01:45:02 pm »
-1
Do you mean hypertonic, hypotonic and isotonic are restricted to osmosis?
I'm very sure they can be used when describing any form of diffusion. After all, osmosis is a form of diffusion.

Like I mentioned, tonicity refers to osmotic pressure so it only relates to solvents such as water. Osmosis is a form of diffusion. Diffusion isn't always about water (tonicity), it can relate to particles and other substances. It would be incorrect to mention hyper/iso/hypo-tonic when referring to regular diffusion.

MM1

  • Victorian
  • Forum Obsessive
  • ***
  • Posts: 213
  • Respect: 0
Re: VCE Biology Question Thread
« Reply #763 on: February 22, 2014, 01:54:15 pm »
0
If anyone can clarify the following that would be greatly appreciated :)

Would you say that facilitated diffusion is the passive, net movement of particles from a region of high concentration to a region of low concentration, via transmembrane proteins?
Or do you have to specify carrier/channel proteins?

Also, cholesterol helps stabilise the phospholipid bilayer by maintaining its rigidity at high temperatures, whilst it maintains the cell membrane's fluidity at low temperatures. If it asks for an explanation, I would say that at high temperatures, it decreases the membrane's permeability to polar substances, while it increases the membrane's permeability to polar substances at low temperatures.

Thanks

I think it would be better to say ' through specific channel/carrier transmembrane proteins'. Also, I think you should specify what type of particles pass through the proteins; so large, polar and charged molecules perhaps.

On that note, any idea on what's the function of peripheral proteins?

RazzMeTazz

  • Victorian
  • Forum Leader
  • ****
  • Posts: 673
  • Respect: 0
Re: VCE Biology Question Thread
« Reply #764 on: February 22, 2014, 03:35:27 pm »
0
Why do scientists study the proteome of an organism, instead of single proteins?

Thanks!