VCE Biology Question Thread

[sunshine98]

Thanks guys!

Are you sure this part is part of signal transduction? Isn't this called reception?

Well yes u are right  in identifying it as reception , but reception is  stage of signal transduction.

[cosine]

With the nervous system:

1). What is the action potential? I know it travels through the axon of the nerve cells, but what is it in physical terms? Do we need to know this?

2). When the neurotransmitters from the pre-synaptic membrane go through exocytosis and are spilled out, do they bind with specific receptor proteins on the post synaptic membrane (dendrite of the next neuron)?

3). If the above is true, what exactly carries out the action potential to the next neuron, is it the Na+ ions that enter the next neuron as the channels are opened from the neurotransmitters?

4). How does the signalling stop in humans? Are the neurotransmitters broken down by enzymes or does the action potential stop?

5). What is the purpose of Ca+ ions in the pre synaptic membrane?

Many thanks

[grannysmith]

With the nervous system:

1). What is the action potential? I know it travels through the axon of the nerve cells, but what is it in physical terms? Do we need to know this?

2). When the neurotransmitters from the pre-synaptic membrane go through exocytosis and are spilled out, do they bind with specific receptor proteins on the post synaptic membrane (dendrite of the next neuron)?

3). If the above is true, what exactly carries out the action potential to the next neuron, is it the Na+ ions that enter the next neuron as the channels are opened from the neurotransmitters?

4). How does the signalling stop in humans? Are the neurotransmitters broken down by enzymes or does the action potential stop?

5). What is the purpose of Ca+ ions in the pre synaptic membrane?

Many thanks

1. An action potential is essentially the depolarisation of an axon through the influx of sodium ions. It's dubbed an ' all or nothing' response because there's a voltage threshold which must be met for the action potential to occur; however, once the threshold level is attained, nothing can stop the action potential from occurring.

2. Yep. This is what induces an action potential in the post synaptic neuron which in turn propagates the nervous signal towards its intended destination.

3. Yep, the binding of the neurotransmitters initiates a signal transduction pathway which eventuates to the opening of sodium ion channels etc.

4. Either broken down or recycled (taken in by the pre synaptic membrane I believe).

5. It is involved in the exocytosis of the neurotransmitters.

[cosine]

1. An action potential is essentially the depolarisation of an axon through the influx of sodium ions. It's dubbed an ' all or nothing' response because there's a voltage threshold which must be met for the action potential to occur; however, once the threshold level is attained, nothing can stop the action potential from occurring.

2. Yep. This is what induces an action potential in the post synaptic neuron which in turn propagates the nervous signal towards its intended destination.

3. Yep, the binding of the neurotransmitters initiates a signal transduction pathway which eventuates to the opening of sodium ion channels etc.

4. Either broken down or recycled (taken in by the pre synaptic membrane I believe).

5. It is involved in the exocytosis of the neurotransmitters.

Question 1 doesn't really answer my question, what is it physically?

You said neurotransmitters initial a signal transduction pathway, my question is, do the neurotransmitters enter the next neuron or do they only play a part in the reception and opening of protein channels?

Thanks!

[grannysmith]

Question 1 doesn't really answer my question, what is it physically?

You said neurotransmitters initial a signal transduction pathway, my question is, do the neurotransmitters enter the next neuron or do they only play a part in the reception and opening of protein channels?

Thanks!

Well, an action potential is not an 'entity' as such - it's a process rather than a structure.

The neurotransmitters are the signalling molecules in this case. They only bind to the post synaptic membrane receptors which activates the sodium ion channels.

[cosine]

Well, an action potential is not an 'entity' as such - it's a process rather than a structure.

The neurotransmitters are the signalling molecules in this case. They only bind to the post synaptic membrane receptors which activates the sodium ion channels.

Okay, thanks for that

So when the neurotransmitters bind to the post synaptic membrane protein receptors (what a mouthful) what happens to them then? Are they immediately recycle of degraded by enzymes?

[grannysmith]

Okay, thanks for that

So when the neurotransmitters bind to the post synaptic membrane protein receptors (what a mouthful) what happens to them then? Are they immediately recycle of degraded by enzymes?

Yes - they're immediately taken up or degraded by enzymes. The significance of this is that the neurons aren't repeatedly being stimulated unnecessarily.

[cosine]

I know the role of second messengers, but what is the difference between g-Protein and cAMP? Are they both second messengers ?

[heids]

I know the role of second messengers, but what is the difference between g-Protein and cAMP? Are they both second messengers ?

Cosine, I didn't get a 50 or anything, but you keep going out of the depth needed.  You get a 50 by knowing everything WITHIN the limits of the study design, as they'll only test this.  If you go too far beyond what you need, you might not be able to spend so much time/brainpower on the things you DO need which could be detrimental.

If you're interested in getting deeper, that's fine since it's a fascinating subject and it's great to learn more, but I'd advise you not to ask questions here but to research it yourself (Wikipedia is awesome, just searching for it on the internet is more likely to be accurate than what we tell you - even the amazing grannysmith ).

See, with this question, before the exam I made sure I a) knew what second messengers were in general and b) recognised the NAMES cyclic AMP and G-protein and associated them with second messengers, so that I wouldn't be thrown when I read about them.    But I didn't bother learning specifically what they were or did, because I figured it was too much in depth and would waste my time and brain-power.  Just now I briefly considered answering your question, but then I thought, "I don't actually know clearly enough so I'd have to google it... and if that's the case, why don't YOU google it and get your own deeper understanding rather than my possibly inaccurate regurgitation?" (Plus it saves me time ).

(Please don't take this as an attack, it was my $0.02 of advice - actually I'm hoping it's worth more than that )

[cosine]

Cosine, I didn't get a 50 or anything, but you keep going out of the depth needed.  You get a 50 by knowing everything WITHIN the limits of the study design, as they'll only test this.  If you go too far beyond what you need, you might not be able to spend so much time/brainpower on the things you DO need which could be detrimental.

If you're interested in getting deeper, that's fine since it's a fascinating subject and it's great to learn more, but I'd advise you not to ask questions here but to research it yourself (Wikipedia is awesome, just searching for it on the internet is more likely to be accurate than what we tell you - even the amazing grannysmith ).

See, with this question, before the exam I made sure I a) knew what second messengers were in general and b) recognised the NAMES cyclic AMP and G-protein and associated them with second messengers, so that I wouldn't be thrown when I read about them.    But I didn't bother learning specifically what they were or did, because I figured it was too much in depth and would waste my time and brain-power.  Just now I briefly considered answering your question, but then I thought, "I don't actually know clearly enough so I'd have to google it... and if that's the case, why don't YOU google it and get your own deeper understanding rather than my possibly inaccurate regurgitation?" (Plus it saves me time ).

(Please don't take this as an attack, it was my $0.02 of advice - actually I'm hoping it's worth more than that )

Well it's not that i want to get into depth but I just do not understand it because my textbook wrote that cAMP is a second messenger, then went to biozone and it said that g-protein is the second messenger that activates cAMP...

Should I just settle that they are both second messengers? Cheers

[heids]

Well it's not that i want to get into depth but I just do not understand it because my textbook wrote that cAMP is a second messenger, then went to biozone and it said that g-protein is the second messenger that activates cAMP...

Should I just settle that they are both second messengers? Cheers

Well, that's what I decided - I figured you don't actually need to know anything specific about either of them.  I believe there are lots of second messengers involved in signal transduction.  Grannysmith will come and settle this point (well he has to now that I've said he will ).

Anyway sorry, I actually wasn't talking much about your question, but more generally trying to point out:
1. It's totally fine (actually very good) to go beyond what you need, but in terms of marks, it may actually disadvantage you.  Just so you're aware of it.
2. If you don't understand, Google it - you learn more out of searching for yourself, and that's what you'll need to do when you get to Uni.  If you STILL don't understand or everything is so in-depth you can't cope, then ask here and someone will always be willing to help .

[grannysmith]

The seemingly overdue Motherload: http://www.vcaa.vic.edu.au/documents/vce/biology/biology-faqs.doc

From the FAQs: "Names of second messengers are not required and G protein pathways do not need to be defined."

VCAA wants you to have a general overview of signal transduction and its various pathways without going into any specifics. As bangali_lok has rightly pointed out, it's probably (sic) good to know that cAMP and G-proteins are involved in second messenger systems.

But if I recall correctly, G-proteins are linked with the receptor to which the ligand binds, initiating a series of reactions involving ATP which then activates the second messenger, cAMP. The fact of the matter is that even if they were to ask you a question on cAMP, the answer they'd be expecting would merely be a general statement on (hydrophilic ligand) signal transduction.

[cosine]

The seemingly overdue Motherload: http://www.vcaa.vic.edu.au/documents/vce/biology/biology-faqs.doc

From the FAQs: "Names of second messengers are not required and G protein pathways do not need to be defined."

VCAA wants you to have a general overview of signal transduction and its various pathways without going into any specifics. As bangali_lok has rightly pointed out, it's probably (sic) good to know that cAMP and G-proteins are involved in second messenger systems.

But if I recall correctly, G-proteins are linked with the receptor to which the ligand binds, initiating a series of reactions involving ATP which then activates the second messenger, cAMP. The fact of the matter is that even if they were to ask you a question on cAMP, the answer they'd be expecting would merely be a general statement on (hydrophilic ligand) signal transduction.

Grannysmith you're the kinslayer or eulerfan of the biology thread!
Thanks for that man. How do you do soo well in bio, I know I've asked you this more than once but when it comes to specifics like this how can we REALLY understand what's going on ? Cheers!

Edit: baglai_lok you are too, thanks for the constant help!

[cosine]

Identify the process that is responsible for the production of ATP during the light dependent stage.

I say the conversion of ADP+Pi into ATP through ATPsynthase? Not sure about this one

[grannysmith]

Identify the process that is responsible for the production of ATP during the light dependent stage.

I say the conversion of ADP+Pi into ATP through ATPsynthase? Not sure about this one

The conversion of ADP+P_i into ATP during an electron transport chain.

Grannysmith you're the kinslayer or eulerfan of the biology thread!
Thanks for that man. How do you do soo well in bio, I know I've asked you this more than once but when it comes to specifics like this how can we REALLY understand what's going on ? Cheers!

Edit: baglai_lok you are too, thanks for the constant help!

In truth, you don't need to know many of the specifics of biology to do well in VCE Biology. Everything VCAA asks you on an exam can be related back to something you've learnt during the course of the year. If this wasn't possible then VCAA would get slammed lol. All you need is a mastery of the basics, and practice in the application of these basics in the form of questions. Although it'd be remiss to state that only a good understanding is needed to do well (you still need to /remember/ concepts), a good understanding is vital in order to make this connection between what a question is asking and a particular concept in your repertoire of bio knowledge.

Haha thanks for the compliment. There are too too many spesh/methods/chem overlords so I feel as though I can only retreat to the biology board...