VCE Biology Question Thread

[randy123]

in mtDNA analysis, is the coding region or non-coding region (hypervariable) analysed?

[PhoenixxFire]

in mtDNA analysis, is the coding region or non-coding region (hypervariable) analysed?

Non-coding.
The coding region is subject to selection pressures so it won’t accurately reflect how many mutations have occurred.

Wait when you say mtDNA analysis what exactly are you referring to? I interpreted it to be evolution? Or do you mean like genetic testing type stuff?

[Erutepa]

Non-coding.
The coding region is subject to selection pressures so it won’t accurately reflect how many mutations have occurred.

Wait when you say mtDNA analysis what exactly are you referring to? I interpreted it to be evolution? Or do you mean like genetic testing type stuff?

I thought that coding regions can also be used, just that the action of natural selection on them reduced the mutation rate as less random mutations will accumulate (as some function-altering mutations will be selected against). This would theoretically make it useful for calculating for longer periods of time (like a longer half-life).
I only say this because I have read quite a few examples of conserved genes like cytochrome C being used for molecular clock analysis.
Please correct me if I am mislead.

[PhoenixxFire]

I thought that coding regions can also be used, just that the action of natural selection on them reduced the mutation rate as less random mutations will accumulate (as some function-altering mutations will be selected against). This would theoretically make it useful for calculating for longer periods of time (like a longer half-life).
I only say this because I have read quite a few examples of conserved genes like cytochrome C being used for molecular clock analysis.
Please correct me if I am mislead.

Yeah I’d imagine that coding regions would be more useful for very long periods of time, to determine when fairly similar species diverged you’d have to use non-coding though due to their hypervariavility otherwise you wouldn’t get a very precise result.

Like for something comparing different populations of humans, you’d want to be using non-coding regions, but for comparing mice to humans you could probably use coding regions.

[Erutepa]

Yeah I’d imagine that coding regions would be more useful for very long periods of time, to determine when fairly similar species diverged you’d have to use non-coding though due to their hypervariavility otherwise you wouldn’t get a very precise result.

Like for something comparing different populations of humans, you’d want to be using non-coding regions, but for comparing mice to humans you could probably use coding regions.

Thanks for clearing that up

[Azim.m]

Do they just mean that it’s used as a baseline for comparing the other results?

[Erutepa]

Do they just mean that it’s used as a baseline for experiment?

Yes.
For this question the first 4 minutes functioned to establish a control/baseline. This would allow comparison of the other results such that any change in the DV was known to be a result of the IV.
 The reason it was 4 minutes particularly (i think i remember the question), was so so the measured values (I think it was CO2 or temperature) stabalized.

[randy123]

how come CO2 is an output in plant anaerobic respiration but not in animal anaerobic respiration?

[darkz]

how come CO2 is an output in plant anaerobic respiration but not in animal anaerobic respiration?

Likewise in yeast, plants and yeasts produce ethanol and carbon dioxide through anerobic respiration in comparison with the lactic acid produced through anerobic respiration in animals. I suppose that this can be directly attributed to the fact that we have different enzymes/metabolic pathways as compared to plants/yeasts, hence even though we use the same substrate, a different product is formed

[PhoenixxFire]

Pretty sure it (evolutionarily) has something to do with products that organisms can handle having in their cells. Don’t need to know that for VCE though, just know what darkdzn said above. (Would be pretty funny if humans made ethanol though)

[persistent_insomniac]

How much detail do we need to know about the extrinsic/intrinsic pathways of apoptosis? Is it enough knowing that the fas ligand binds to the fas receptor, caspases activated and then the steps of destruction (e.g. blebbing, phagocytes arrive etc)?

[Erutepa]

Pretty sure it (evolutionarily) has something to do with products that organisms can handle having in their cells. Don’t need to know that for VCE though, just know what darkdzn said above. (Would be pretty funny if humans made ethanol though)

I would agree with that being funny, and it might get more people running.
On the evolutionary advantage thing, I believe some single-celled organisms such as some yeast will even preferentially produce energy via fermentation over aerobic respiration in certain scenarios as the production of ethanol (which it can handle) kills of competing for neighboring organisms.

How much detail do we need to know about the extrinsic/intrinsic pathways of apoptosis? Is it enough knowing that the fas ligand binds to the fas receptor, caspases activated and then the steps of destruction (e.g. blebbing, phagocytes arrive etc)?

This is all good for the extrinsic, though you should probably know that the caspases cause cell destruction by cleavage of cell elements like the cytoskeleton.
For the intrinsic, you should know that it is initiated by the mitochondria in the case of cell stress or recognition of irreversible damage which then causes caspase activation.

[vox nihili]

How much detail do we need to know about the extrinsic/intrinsic pathways of apoptosis? Is it enough knowing that the fas ligand binds to the fas receptor, caspases activated and then the steps of destruction (e.g. blebbing, phagocytes arrive etc)?

I'd avoid talking about fas, it's never really talked about in the VCE course.

You should generally know that there are internal and external (death ligand) signals that can trigger apoptosis and that caspases are the enzymes involved with effecting apoptosis, namely death of the cell. I don't think it's really necessary to know much beyond this, though some might argue that having a knowledge of the mitochondrion's involvement in this pathway may be useful.

[PhoenixxFire]

I don't think it's really necessary to know much beyond this, though some might argue that having a knowledge of the mitochondrion's involvement in this pathway may be useful.

Given they’ve called it the mitochondrial pathway on the study design, rather than just calling it the intrinsic pathway, I think it’s important to understand the basics of the mitochondria’s involvement.

[persistent_insomniac]

Thankyou!!
Also in the intrinisic pathway does the signalling molecule bind to an intracellular receptors or is it just called this because its initiated by internal signals? And is it correct to say that caspases cleave specific proteins in the nucleus, cytoplasm and cytoskeleton to cause the cell to lose its shape?

Mod edit (PF): Merged double post