Yacoubb's Bio 3+4 Questions

[Yacoubb]

I got a question on a practice exam for unit 4 on transgenic zebra fish. A gene from sea coral was inserted into the genome of the zebra fish eggs. So the Glofish glew fluorescently.

Predict the chance of survival of the Glofish if it were released into the natural environment of the zebra fish. Explain your answer.

My answer was COMPLETELY opposite to VCAAs, in that I mentioned their chances of survival increased. This was my answer:
The chances of survival of the Glofish would increase because the bright fluorescent glow would trick predators into believing they are poisonous. Hence, predation is reduced, thereby increasing the chance of survival o the Glofish in the natural environment of the zebra fish.

VCAA's answer:
The survival of the Glofish is likely to be poor in the natural environment. The fish would be more noticeable to predators because it is red or glows in ultraviolet light, so may be captured more often.

Would my answer be considered right because of my justification.

[alondouek]

No, your answer would not be correct.

Take as an analogy the anglerfish; it has a luminous protrusion called an illicium that it uses to attract prey. Fish - living in a light-poor environment - are naturally attracted to fluorescence. From this, you can take that if we were to put a fish that fluoresces into the natural environment, it would become more appealing to predators. As such, the fishes chances of survival decrease.

[pi]

^Agreed, your answer is definitely incorrect.

[Yacoubb]

No, your answer would not be correct.

Take as an analogy the anglerfish; it has a luminous protrusion called an illicium that it uses to attract prey. Fish - living in a light-poor environment - are naturally attracted to fluorescence. From this, you can take that if we were to put a fish that fluoresces into the natural environment, it would become more appealing to predators. As such, the fishes chances of survival decrease.

Hmm, it's just because I've come across a question similar to this once and it was also a light-poor environment, and the fluorescent glow made them seem poisonous. Any tips on knowing when to go with what approach? For instance, how would I know the fluorescence in this instance decreased the biological fitness of the fish?

[alondouek]

Hmm, it's just because I've come across a question similar to this once and it was also a light-poor environment, and the fluorescent glow made them seem poisonous. Any tips on knowing when to go with what approach? For instance, how would I know the fluorescence in this instance decreased the biological fitness of the fish?

It's more common sense than anything, really - you need to apply wider biological principles to situations while maintaining a logical view (in biology, the logical way of something occurring is probably the true way it occurs, even if it isn't immediately obvious).

For the Glofish example, you need to think about 1. The characteristics of the aquatic environment, 2. The characteristics of unaltered fish in that environment and why they have the adaptations that they do, and 3. The characteristics of the altered fish and how these alterations affect fitness.

Just as a general rule (obviously fraught with exceptions) - the more colourful an organism is, the more attractive it is designed to be to prey.

The 'poisonous' example was probably something to do with the predator having a bright colour in order to entice prey, as opposed to our example where we've manipulated the prey in such a way that it is more enticing to the predator.

Hope this makes sense!

[Yacoubb]

When cells of a transplanted organ are detected as 'non-self' by cells of the immune system of the organ recipient, is the transplanted organ rejected as a result of specific antibodies being produced against these cells?

^ I thought that rejection of tissue/organs would involve cytotoxic t-cells, but that doesn't seem to be the case in an exam I did. They've mention that skin grafts detected as non-self by the immune system of mice were rejected as specific antibodies against the skin grafts were produced, leading to the rejection of the skin graft.

Could someone please just clarify this? Thanks

[vox nihili]

When cells of a transplanted organ are detected as 'non-self' by cells of the immune system of the organ recipient, is the transplanted organ rejected as a result of specific antibodies being produced against these cells?

^ I thought that rejection of tissue/organs would involve cytotoxic t-cells, but that doesn't seem to be the case in an exam I did. They've mention that skin grafts detected as non-self by the immune system of mice were rejected as specific antibodies against the skin grafts were produced, leading to the rejection of the skin graft.

Could someone please just clarify this? Thanks

Antibodies sounds about right. It's because you're interacting with foreign antigens. That inherently suggests antibodies. It's the safer bet in any case. The VCE course is very light on immunology, so things like this often happen. You're trying to string together a picture with so few of the facts. Sadly the same thing happens in first year, so I've still got no clue about any of it!

[Yacoubb]

Antibodies sounds about right. It's because you're interacting with foreign antigens. That inherently suggests antibodies. It's the safer bet in any case. The VCE course is very light on immunology, so things like this often happen. You're trying to string together a picture with so few of the facts. Sadly the same thing happens in first year, so I've still got no clue about any of it!

Yeah I'll just stick with specific antibodies being produced against the detected non-self tissue. Thanks t-rav!

[simpak]

You can definitely say antibodies, but there are actually three kinds of rejection responses and two are relevant here:
The first is 'hyperacute' and occurs because of antibody binding, the second is 'acute' and is largely T cell mediated.
T cells are the most important cell to coordinate a rejection response.  They are the most important thing for most everything, though.  Ever.  In the world. 

[thecreeker]

OK can I get this straight

Does mitochondrial DNA have a faster or slower mutation rate than nuclear DNA? Is it faster in the coding/non-coding region, and slower in the other region?
A lot of the resources I have looked at are contradicting, and not one gives a definitive answer

Thank youuu

[thecreeker]

And one more thing, what exactly is a haplogroup, and its relevance to Mitochondrial DNA?
How can haplogroups be used to compare polpulations more effectively than nuclear DNA?
Thanks again

[Yacoubb]

OK can I get this straight

Does mitochondrial DNA have a faster or slower mutation rate than nuclear DNA? Is it faster in the coding/non-coding region, and slower in the other region?
A lot of the resources I have looked at are contradicting, and not one gives a definitive answer

Thank youuu

The coding regions of mitochondrial DNA have a very slow mutation rate, and so this is used to determine evolutionary relationships between species with no recent common ancestry, and the non-coding region (D-loop in hypervariable region of mitochondrial DNA) has a very high mutation rate. Because of this, the non-coding region is used to determine the degree of not-too-distantly related species. That is, species with a recent common ancestor.

Hope this helped.

[Yacoubb]

And one more thing, what exactly is a haplogroup, and its relevance to Mitochondrial DNA?
How can haplogroups be used to compare polpulations more effectively than nuclear DNA?
Thanks again

You don't need to know about haplogroups. However, as part of the Out-of-Africa hypothesis, which states that Homo Sapiens evolved in Africa prior to emigrating from the African continent, and as a result, a large degree of variation is expected to exist in the mtDNA of the African population.

[Irving4Prez]

The coding regions of mitochondrial DNA have a very slow mutation rate, and so this is used to determine evolutionary relationships between species with no recent common ancestry

Wasn't it to determine evolutionary relationships between species with common ancestry?

[simpak]

All species will have common ancestry to some degree, but what Yacoubb is saying is that if species diverged from a common ancestor long ago you would use mitochondrial DNA to detect changes - otherwise the differences in the genome are too large to make any kind of direct comparison between the organisms.

Recent was the key word in his response.