VCE Biology Question Thread

[TheAspiringDoc]

People often say 'bacteria' when they mean 'eubacteria'. However, the technical name for archaea is archaebacteria. In an exam scenario when you're asked about bacteria, what is the exam referring to?

[Photon]

People often say 'bacteria' when they mean 'eubacteria'. However, the technical name for archaea is archaebacteria. In an exam scenario when you're asked about bacteria, what is the exam referring to?

I once read that arachaeabacteria should be properly referred to as archaea because arachaeabacteria is an outdated term. Don't ask me why they changed it.

[vox nihili]

People often say 'bacteria' when they mean 'eubacteria'. However, the technical name for archaea is archaebacteria. In an exam scenario when you're asked about bacteria, what is the exam referring to?

I once read that arachaeabacteria should be properly referred to as archaea because arachaeabacteria is an outdated term. Don't ask me why they changed it.

I'm with photon on this. Archaea and bacteria are the words that should be used. Archaea is barely even a thing on the VCE course... To my knowledge a question has never, ever, ever been asked that required any knowledge of it

It's often said that one should read widely when studying biology. Would anyone be able to recommend some relatively advanced (i.e. not fluffy newspaper article type stuff) reading material?

Thanks

EDIT: Guys I had an idea (ikr - how amazing!)

I thought maybe we could make a thread on AN where rather than asking questions, we actually just post things that we've learnt (in bio) that we find intersting/cool etc?

The Conversation has relatively good up-to-date stuff

[skybluemaniac]

I've been reading up on DNA, and although I'm defs no expert in this stuff I've had a little bit of a funny idea.

The general consensus is that the non-coding regions of DNA are just junk/remnants/protective measures against mutations in the coding regions of DNA. However, my thought is that perhaps this non-coding DNA could actually be lying in wait for further evolution?

Now I know that we do have genes that do things like code for wings and stuff, but the're just not activated (right?  ), but what if we were to want to evolve a completely new, never-seen-before type structure? perhaps all these regions of non-coding are like susceptible or something to such mutations?

Obviously this ain't my strong point LOL so I'm kinda hoping to put it out there for discussion, but yah, I just thought this was an interesting idea

You are definitely onto something there! I forgot where but I think I read something about how genes can accumulate mutations which render them inactive...so it is very well possible that mutations in introns can mutate to code for something completely new! Of course, the chances that the mutation codes for something that benefits the organism and does not kill it as well as factoring in that this mutation must occur within the germ line cells (which give rise to gametes, and so can be passed onto the next generation) is slim. You should look up lactase persistence! Not sure if it has to do with introns but the evolutionary history is fascinating!

[vox nihili]

I've been reading up on DNA, and although I'm defs no expert in this stuff I've had a little bit of a funny idea.

The general consensus is that the non-coding regions of DNA are just junk/remnants/protective measures against mutations in the coding regions of DNA. However, my thought is that perhaps this non-coding DNA could actually be lying in wait for further evolution?

Now I know that we do have genes that do things like code for wings and stuff, but the're just not activated (right?  ), but what if we were to want to evolve a completely new, never-seen-before type structure? perhaps all these regions of non-coding are like susceptible or something to such mutations?

Obviously this ain't my strong point LOL so I'm kinda hoping to put it out there for discussion, but yah, I just thought this was an interesting idea

You are definitely onto something there! I forgot where but I think I read something about how genes can accumulate mutations which render them inactive...so it is very well possible that mutations in introns can mutate to code for something completely new! Of course, the chances that the mutation codes for something that benefits the organism and does not kill it as well as factoring in that this mutation must occur within the germ line cells (which give rise to gametes, and so can be passed onto the next generation) is slim. You should look up lactase persistence! Not sure if it has to do with introns but the evolutionary history is fascinating!

NOT VCE BIOLOGY

Interesting thoughts by both. I think it's good to think this way, in Biology at school and science more generally—it's what makes for a good science student and indeed scientist.

I think it's probably unreasonable to say that the general consensus is that non-coding regions of DNA are junk/remnants. Certainly it had been for a very long period of time and is probably still approached as such in VCE, but quite a great deal of work in genetics and indeed molecular biology now focuses on non-coding regions. There's a rich variety of things that such regions can do.

Without getting too bogged down in the details or making things too complicated, the non-coding regions, for instance, control the activity of coding regions. In the non-coding DNA are elements such as promoters, operators and so on. These elements interact with the enzymes that are responsible for the transcription of DNA. Without such regions, DNA could not be transcribed.

Sometimes repeats of short sequences of DNA actually serve a really important purpose. In Plasmodium falciparum (i.e. the protozoan that causes malaria), series of similar sequence are found scattered around chromosomes, particularly at the end. These sequences are homologous and therefore facilitate recombination between non-homologous chromosomes. THis special type of recombination is very rare and is called ectopic recombination. The purpose of ectopic recombination is to encourage variability in the genes coding for proteins expressed on the surface of red-blood cells infected with Plasmodium. This helps Plasmodium hide away from the immune system.


These are just a couple of examples but there are countless others. The majority of junk DNA appears to be there because our ancestors have collected pseudogenes (i.e. the genes alluded to by both of you that are remnants of genes that once coded) and, even more so, viruses. The vast majority of non-coding DNA is actually taken up by latent viruses. If memory serves me correctly, I think it's something like half of all non-coding DNA, or even perhaps half of our DNA overall that is actually made up by viruses (don't quote me on it, but it is a very large proportion).

[TheAspiringDoc]

You are definitely onto something there! I forgot where but I think I read something about how genes can accumulate mutations which render them inactive...so it is very well possible that mutations in introns can mutate to code for something completely new! Of course, the chances that the mutation codes for something that benefits the organism and does not kill it as well as factoring in that this mutation must occur within the germ line cells (which give rise to gametes, and so can be passed onto the next generation) is slim. You should look up lactase persistence! Not sure if it has to do with introns but the evolutionary history is fascinating!

Good stuff - thanks!
In the big picture of things, is it favourable or not for germ line cells to have a higher rate of mutation than somatic cells? And, does the body have any mechanisms to achieve this favourable rate (e.g. expose germ line cells to mutagens etc.)?

[TheAspiringDoc]

NOT VCE BIOLOGY

Interesting thoughts by both. I think it's good to think this way, in Biology at school and science more generally—it's what makes for a good science student and indeed scientist.

I think it's probably unreasonable to say that the general consensus is that non-coding regions of DNA are junk/remnants. Certainly it had been for a very long period of time and is probably still approached as such in VCE, but quite a great deal of work in genetics and indeed molecular biology now focuses on non-coding regions. There's a rich variety of things that such regions can do.

Without getting too bogged down in the details or making things too complicated, the non-coding regions, for instance, control the activity of coding regions. In the non-coding DNA are elements such as promoters, operators and so on. These elements interact with the enzymes that are responsible for the transcription of DNA. Without such regions, DNA could not be transcribed.

Sometimes repeats of short sequences of DNA actually serve a really important purpose. In Plasmodium falciparum (i.e. the protozoan that causes malaria), series of similar sequence are found scattered around chromosomes, particularly at the end. These sequences are homologous and therefore facilitate recombination between non-homologous chromosomes. THis special type of recombination is very rare and is called ectopic recombination. The purpose of ectopic recombination is to encourage variability in the genes coding for proteins expressed on the surface of red-blood cells infected with Plasmodium. This helps Plasmodium hide away from the immune system.


These are just a couple of examples but there are countless others. The majority of junk DNA appears to be there because our ancestors have collected pseudogenes (i.e. the genes alluded to by both of you that are remnants of genes that once coded) and, even more so, viruses. The vast majority of non-coding DNA is actually taken up by latent viruses. If memory serves me correctly, I think it's something like half of all non-coding DNA, or even perhaps half of our DNA overall that is actually made up by viruses (don't quote me on it, but it is a very large proportion).

Trav for president!

Can things like the poly(A) tail on mRNA also cause some sort of ectopic recombination? Even so, I suppose that wouldn't really matter though because unless you went through the whole reverse transcriptase thing and created cDNA out of it, it would only be a one-off, right?

[vox nihili]

Trav for president!

Can things like the poly(A) tail on mRNA also cause some sort of ectopic recombination? Even so, I suppose that wouldn't really matter though because unless you went through the whole reverse transcriptase thing and created cDNA out of it, it would only be a one-off, right?

RNA can't recombine, as far as I'm aware, so no. Ectopic recombination is pretty rare and we don't really know that much about it.

Just on your idea, skybluemaniac, the idea that introns would accrue mutations and then pop up as a completely new gene is pretttttttty slim. The chances of that happening are incredibly low. Almost impossible.

[skybluemaniac]

Just on your idea, skybluemaniac, the idea that introns would accrue mutations and then pop up as a completely new gene is pretttttttty slim. The chances of that happening are incredibly low. Almost impossible.

How about non-coding DNA? I think I muddled up introns and non-coding DNA and thought they were the same when I typed the reply....or maybe I'm completely wrong I have no idea! Just trying to think outside the box

[Photon]

I've been reading up on DNA, and although I'm defs no expert in this stuff I've had a little bit of a funny idea.

The general consensus is that the non-coding regions of DNA are just junk/remnants/protective measures against mutations in the coding regions of DNA. However, my thought is that perhaps this non-coding DNA could actually be lying in wait for further evolution?

Now I know that we do have genes that do things like code for wings and stuff, but the're just not activated (right?  ), but what if we were to want to evolve a completely new, never-seen-before type structure? perhaps all these regions of non-coding are like susceptible or something to such mutations?

Obviously this ain't my strong point LOL so I'm kinda hoping to put it out there for discussion, but yah, I just thought this was an interesting idea

I remember I once watched a Ted Ed video that talked about a similar topic to this, how the introns of DNA were mutated and that served a purpose in evolution. I think it was called "Where did DNA come from?" or something

[TheAspiringDoc]

When MHC class I expression is low, as is typically the case with abnormal cell function during viral infection or tumourigenesis, NK cells lose the inhibitory KIR signal and trigger programmed cell death of the abnormal cell.

-wikipedia

This is wrong because it says that an extracellular entity is triggering PCD, yeah?

[Biology24123]

-wikipedia

This is wrong because it says that an extracellular entity is triggering PCD, yeah?

Where does it say that

[TheAspiringDoc]

Where does it say that

On the MHC page, under the heading lymphocytes.

[Biology24123]

On the MHC page, under the heading lymphocytes.

It doesn't suggest PCD caused by an extracellular entity

[TheAspiringDoc]

It doesn't suggest PCD caused by an extracellular entity

Correct me if I'm wrong, but the NK cells are extracellular with respect to the cell undergoing tumorigenesis or what have you. It then states that cells undergoing tumourigenesis will be forced to undertake PCD by the NK cells.