Login

Welcome, Guest. Please login or register.

March 29, 2024, 09:11:27 pm

Author Topic: VCE Biology Question Thread  (Read 3571584 times)  Share 

0 Members and 16 Guests are viewing this topic.

vox nihili

  • National Moderator
  • Great Wonder of ATAR Notes
  • *****
  • Posts: 5343
  • Respect: +1447
Re: VCE Biology Question Thread
« Reply #795 on: February 23, 2014, 03:00:42 pm »
+2
Not sure if my answer to this question is correct. Can someone verify?

Carbon monoxide, a molecule in cigarette smoke and car exhaust fumes, binds irreversibly with iron groups. What effect would this have on your red blood cells?

Carbon monoxide can bind to the iron groups present in hemoglobin. This can cause the irreversible disruption of ionic bonds in hemoglobin, causing it to denature and lose its function in red blood cells.

Don't repeat the stem of the question. It's not really binding to iron groups either, that's somewhat of an incorrect way to put it so bad question.

It's competitive inhibition, not denaturation. The way to pick that would've been to take note that it says "irreversibly", it will not leave that place once it has bound.
2013-15: BBiomed (Biochemistry and Molecular Biology), UniMelb
2016-20: MD, UniMelb
2019-20: MPH, UniMelb
2021-: GDipBiostat, USyd

MM1

  • Victorian
  • Forum Obsessive
  • ***
  • Posts: 213
  • Respect: 0
Re: VCE Biology Question Thread
« Reply #796 on: February 23, 2014, 03:02:20 pm »
0
Not sure if my answer to this question is correct. Can someone verify?

Carbon monoxide, a molecule in cigarette smoke and car exhaust fumes, binds irreversibly with iron groups. What effect would this have on your red blood cells?

Carbon monoxide can bind to the iron groups present in hemoglobin. This can cause the irreversible disruption of ionic bonds in hemoglobin, causing it to denature and lose its function in red blood cells.

I'm going to attempt this; Carbon monoxide inhibits oxygen to bind to haemoglobin which is needed to be delivered to cells for cellular respiration. RBC would not be able to deliver oxygen so cells would eventually die.

My wording is not the best, but would I be correct, anyone?

Edit: Already answered by Mr. T-Rav; thanks! :)
« Last Edit: February 23, 2014, 03:10:21 pm by MM1 »

alchemy

  • Victorian
  • Part of the furniture
  • *****
  • Posts: 1222
  • Respect: +25
Re: VCE Biology Question Thread
« Reply #797 on: February 23, 2014, 03:23:41 pm »
0
It's competitive inhibition, not denaturation. The way to pick that would've been to take note that it says "irreversibly", it will not leave that place once it has bound.

If it binds "irreversibly" shouldn't it be an example of non-competitive (permanent) inhibition, as carbon monoxide binding to haemoglobin would have caused its active site to change shape, preventing oxygen from binding onto its active site?

vox nihili

  • National Moderator
  • Great Wonder of ATAR Notes
  • *****
  • Posts: 5343
  • Respect: +1447
Re: VCE Biology Question Thread
« Reply #798 on: February 23, 2014, 03:27:12 pm »
+1
I'm going to attempt this; Carbon monoxide inhibits oxygen to bind to haemoglobin which is needed to be delivered to cells for cellular respiration. RBC would not be able to deliver oxygen so cells would eventually die.

My wording is not the best, but would I be correct, anyone?

Edit: Already answered by Mr. T-Rav; thanks! :)

You're right about the cell thing as well too of course. Carbon monoxide is bloody dangerous. You hear stories every so often particularly about it killing kids. Faulty heaters and stuff like that produce it. It's also what gets people when they use car fumes to commit suicide, an all too common occurrence sadly.

The binding is technically not reversible, but haemoglobin's affinity for carbon monoxide is about 10,000 times that for oxygen, so you're pretty well toast if you're exposed.




If it binds "irreversibly" shouldn't it be an example of non-competitive (permanent) inhibition, as carbon monoxide binding to haemoglobin would have caused its active site to change shape, preventing oxygen from binding onto its active site?

You're probably right actually. It's been a few years since I've done inhibition and I always found the terminology to be a little odd, so if that's the case then sure it's probably right. Would love someone else to confirm.
I'd thought that competitive inhibition was when another molecule binds to the active site. Hence, competitive because it competes for the active site. And non-competitive when it's bound to another area and changed the config of the active site.
2013-15: BBiomed (Biochemistry and Molecular Biology), UniMelb
2016-20: MD, UniMelb
2019-20: MPH, UniMelb
2021-: GDipBiostat, USyd

MM1

  • Victorian
  • Forum Obsessive
  • ***
  • Posts: 213
  • Respect: 0
Re: VCE Biology Question Thread
« Reply #799 on: February 23, 2014, 03:27:33 pm »
0
According to A+ biol notes, Inhibition is reversible..

Edit: Denaturing and the binding of poisons is irreversible. So since CO is a poison, it would be irreversible.
« Last Edit: February 23, 2014, 03:31:30 pm by MM1 »

grannysmith

  • Victorian
  • Part of the furniture
  • *****
  • Posts: 1303
  • Crisp and juicy.
  • Respect: +66
Re: VCE Biology Question Thread
« Reply #800 on: February 23, 2014, 03:45:48 pm »
0
But it's still competitive inhibition, no? I'm guessing because the bonding is so strong, it might as well be irreversible.
But don't they like treat severe cases of carbon monoxide poisoning with 100% oxygen?

vox nihili

  • National Moderator
  • Great Wonder of ATAR Notes
  • *****
  • Posts: 5343
  • Respect: +1447
Re: VCE Biology Question Thread
« Reply #801 on: February 23, 2014, 03:48:34 pm »
+1
According to A+ biol notes, Inhibition is reversible..

Edit: Denaturing and the binding of poisons is irreversible. So since CO is a poison, it would be irreversible.

Assume that your edit is true. Technically it's not, every process is reversible, but yes this process is practically irreversible.

But it's still competitive inhibition, no? I'm guessing because the bonding is so strong, it might as well be irreversible.
But don't they like treat severe cases of carbon monoxide poisoning with 100% oxygen?

Yeah, just to get some oxygen into the blood presumably. Haemoglobin doesn't stick around too long, and it would be somewhat unlikely for CO to saturate all the sites, although the majority yes.

Important: what I said about inhibition earlier was correct. It is competitive inhibition.
2013-15: BBiomed (Biochemistry and Molecular Biology), UniMelb
2016-20: MD, UniMelb
2019-20: MPH, UniMelb
2021-: GDipBiostat, USyd

alchemy

  • Victorian
  • Part of the furniture
  • *****
  • Posts: 1222
  • Respect: +25
Re: VCE Biology Question Thread
« Reply #802 on: February 23, 2014, 04:38:16 pm »
0
If the lock and key model were true, only one enzyme would be able to catalyze a reaction. However, some enzymes can catalyze multiple reactions. What are some examples of enzymes that can catalyze multiple reactions?


vox nihili

  • National Moderator
  • Great Wonder of ATAR Notes
  • *****
  • Posts: 5343
  • Respect: +1447
Re: VCE Biology Question Thread
« Reply #803 on: February 23, 2014, 04:48:32 pm »
0
Another point to make about haemoglobin as well: it's not an enzyme. The process of ligation, though, is fairly similar in this case, hence the reason they've asked this question.
2013-15: BBiomed (Biochemistry and Molecular Biology), UniMelb
2016-20: MD, UniMelb
2019-20: MPH, UniMelb
2021-: GDipBiostat, USyd

MM1

  • Victorian
  • Forum Obsessive
  • ***
  • Posts: 213
  • Respect: 0
Re: VCE Biology Question Thread
« Reply #804 on: February 23, 2014, 04:55:01 pm »
0
If the lock and key model were true, only one enzyme would be able to catalyze a reaction. However, some enzymes can catalyze multiple reactions. What are some examples of enzymes that can catalyze multiple reactions?

Lysozyme perhaps?

vox nihili

  • National Moderator
  • Great Wonder of ATAR Notes
  • *****
  • Posts: 5343
  • Respect: +1447
Re: VCE Biology Question Thread
« Reply #805 on: February 23, 2014, 04:58:42 pm »
0
If the lock and key model were true, only one enzyme would be able to catalyze a reaction. However, some enzymes can catalyze multiple reactions. What are some examples of enzymes that can catalyze multiple reactions?

You'll be hard pressed to find an example to be honest. The reality is that enzymes really don't catalyse different reactions at the same active site, though some will have multiple active sites. I'm sure there are probably a very specific few exceptions to that rule, but none would do it "normally".
2013-15: BBiomed (Biochemistry and Molecular Biology), UniMelb
2016-20: MD, UniMelb
2019-20: MPH, UniMelb
2021-: GDipBiostat, USyd

nerdmmb

  • Guest
Re: VCE Biology Question Thread
« Reply #806 on: February 23, 2014, 05:44:07 pm »
0
Can someone describe the structure of the membrane of organelles?

Do they also have protein channels, etc.?

Also, is ribosome referred to a  non-membrane bound organelle because it does not have a phospholipid bilayer? If so, what is the membrane of ribosome like?

Thanks!

vox nihili

  • National Moderator
  • Great Wonder of ATAR Notes
  • *****
  • Posts: 5343
  • Respect: +1447
Re: VCE Biology Question Thread
« Reply #807 on: February 23, 2014, 05:57:03 pm »
+2
Can someone describe the structure of the membrane of organelles?

Do they also have protein channels, etc.?

Also, is ribosome referred to a  non-membrane bound organelle because it does not have a phospholipid bilayer? If so, what is the membrane of ribosome like?

Thanks!

The structure of organelle membranes is pretty different to that of the cell itself, but in a very broad stroke, they are essentially the same kind of thing. Phospholipid and whatnot, most will have protein channels though it does depend on the organelle. FOr example, you should already have some insights into the membrane of most of the organelles you've already encountered. A little bit of a recap:

Nucleus: bilayer that folds in on itself to make pores.
Mitochondria: internal and external membranes, lots of membrane proteins particularly in the internal membrane (think ETC). Naturally, there are channels/carriers on the external membrane to let proteins in and out
Chloroplast: similar story to mitochondria, two membranes (gram -), thylakoids on the inside
ER: pretty similar to cell, though studied with ribosomal complexes
Golgi: practically identical to the cellular membrane. Pretty much all golgi membrane eventually becomes cell membrane anyway, so they have to be very similar. Although, the membrane in the Golgi actually undergoes changes, becoming more and more structurally similar to the cell as it gets closer to budding off.

Ribosomes don't have a membrane at all. They're just a big hunk of protein and rRNA
2013-15: BBiomed (Biochemistry and Molecular Biology), UniMelb
2016-20: MD, UniMelb
2019-20: MPH, UniMelb
2021-: GDipBiostat, USyd

alchemy

  • Victorian
  • Part of the furniture
  • *****
  • Posts: 1222
  • Respect: +25
Re: VCE Biology Question Thread
« Reply #808 on: February 23, 2014, 05:57:44 pm »
+1
Also, is ribosome referred to a  non-membrane bound organelle because it does not have a phospholipid bilayer? If so, what is the membrane of ribosome like?

A ribosome is a small non-membrane bound organelle. 'Non-membrane bound' means it doesn't have a membrane surrounding itself.

vox nihili

  • National Moderator
  • Great Wonder of ATAR Notes
  • *****
  • Posts: 5343
  • Respect: +1447
Re: VCE Biology Question Thread
« Reply #809 on: February 23, 2014, 06:22:46 pm »
+2
This is what one looks like (only a very recent discovery, and actually earned them a nobel prize!)

2013-15: BBiomed (Biochemistry and Molecular Biology), UniMelb
2016-20: MD, UniMelb
2019-20: MPH, UniMelb
2021-: GDipBiostat, USyd