Exam Discussion

[duquesne9995]

Couldn't see properly whether this was already explained but here's my thoughts on the polypeptide qn:

Did they ask for the relative amount of polypeptide (which would have been a substrate for a protease enzyme in the stomach - that's what I inferred from what you guys are talking about) for each temperature? I havent seen the exam paper yet.

At 10 degrees, the proteases are working but slowly. So the amount of polypeptide would be relatively high (because only some of the polypeptide has been broken down).

At 37 degrees, the proteases are probs working at optimum level. So the amount of polypeptide would be low (because most of the polypeptide has been broken down).

At 80 degrees, the proteases are denatured and do not work [80 degrees does not break COVALENT bonds, it breaks hydrogen bonds], so cannot convert polypepeptide substrate into its amino acids. So the amount of polypeptide would be higher than that in 10 degrees (as none of it has been broken down).

Was that what the question was asking?

Yeh the q was similar to that but in the graph, they gave you the level for the 37 degrees one which was already fairly high. The y-axis was in arbitrary units and the maximum value on the y-axis was 40, and the level for the 37 degrees one was 30 if i remember correctly. That's what was misleading
but thanks for you help, I think I did what you said

[ligands]

i put the 10 degree one as the same height as the 37 degree one, this is incorrect isn't it?

[thushan]

Couldn't see properly whether this was already explained but here's my thoughts on the polypeptide qn:

Did they ask for the relative amount of polypeptide (which would have been a substrate for a protease enzyme in the stomach - that's what I inferred from what you guys are talking about) for each temperature? I havent seen the exam paper yet.

At 10 degrees, the proteases are working but slowly. So the amount of polypeptide would be relatively high (because only some of the polypeptide has been broken down).

At 37 degrees, the proteases are probs working at optimum level. So the amount of polypeptide would be low (because most of the polypeptide has been broken down).

At 80 degrees, the proteases are denatured and do not work [80 degrees does not break COVALENT bonds, it breaks hydrogen bonds], so cannot convert polypepeptide substrate into its amino acids. So the amount of polypeptide would be higher than that in 10 degrees (as none of it has been broken down).

Was that what the question was asking?

That was one interpretation. My one was the heated discussion earlier haha about proteins being broken down into polypeptides. Though I think your reasoning makes sense too

Oh fair enough - but the issue with that is that the proteases would in turn break down the polypeptides into amino acids. :/

[Shenz0r]

Yeah, when I drew that graph, even though I read "polypeptide" in the axis, for some stupid reason it didn't register in my brain and I immediately started drawing the graph of how much stuff had been broken down. (Damn you)

And the baby receiving IgG and IgM antibodies, what was with that? It was down to B or D, and after I went through my MCQ I rubbed out D and shaded B, because I thought that:

*If the baby was infected during fetal development, they wouldn't have the capacity to produce antibodies yet because their immune system would be so weak (and the question stated that IgM couldn't be passed through the placenta)

But then I was unsure because passive immunity would never lasts for two years. Grrrr.

And then the yellow fever one, I assumed that you could also spread the disease through human contact as well as mosquitoes, because NK cells would destroy virally-infected cells and you'd eventually cough up the debris and potentially cough the virus out, so I wrote cilia for one of the first lines of defence, but apparently yellow fever can't be spread human-to-human....

I feel quite depressed now, it wasn't even a hard exam sigh

[vagrantshades]

It does make sense that the baby would be too weak to produce IgM antibodies, but at the same time, what's the guarantee that the baby will receive passive immunity over the next two years? That's only if the baby is breastfed...and baby formula is readily available nowadays, so that isn't really GUARANTEED.

Some very strange MC questions this year imo. And that agglutination question? o_O I went for D because it was the only one that looked different, despite that it should still occur in options B and C.

[InsaneMcFries]

No, the agglutination question referred to the ANTIBODIES against the antigens, not the antigens themselves. D was the only correct option.

The question said that the newborns had never been breastfed, so from the information it is definitely unreasonable to say that passive immunity will last 2 years. D is sketchy but it is most logical.

[amilss]

I cant really remember the question but to the best of my knowledge it wasnt an answer with passive immunity, as it said the antibodies couldnt cross the placenta, and there was no mention of whether the babies were breastfed

[G-lain]

Wasn't the answer for the babies that the mum had immunity against the virus? I didn't think the other three options made any sense.

[Russ]

Post the actual question?

If you've never been breast fed, your antibodies won't last 2 years though

[diam0nds]

I cant really remember the question but to the best of my knowledge it wasnt an answer with passive immunity, as it said the antibodies couldnt cross the placenta, and there was no mention of whether the babies were breastfed

was the answer active induced immunity? i don't actually remember the question though haha

[lukeim]

But would the babies have IgM antibodies if their immune system has not developed yet?, cause it mentions it was just born and IgM antibodies cannot path through the placenta.
Although 2years sound dodgy, the others didn't make sense. I just assumed it will get breast fed and some babies get breast fed until the age of 2 so lol... such a stupid question

[Shenz0r]

It's possible that they could have gotten IgG antibodies through an injection...but that is wishful thinking

Is it still possible to get 45 if you're estimating that you've dropped around 10 marks for worst-case scenario

[InsaneMcFries]

It was something like this.

There are four newborns and their mothers when pregnant were infected with the rubella viruses. Antibodies IgM and IgG are produced by the mother. IgM cannot pass through the placenta. Babies haven't been fed.

Baby 1: No antibodies
Baby 2: IgG
Baby 3: IgM
Baby 4: IgM

A - Baby 1's mother had immunity to Rubella.
B - Baby 2 will have 2 years passive immunity.
C - Baby 3 got IgM through the placenta.
D - Baby 4 got infected with rubella during fetal development.

I chose D, as did most others.

[lukeim]

It was something like this.

There are four newborns and their mothers when pregnant were infected with the rubella viruses. Antibodies IgM and IgG are produced by the mother. IgM cannot pass through the placenta. Babies haven't been fed.

Baby 1: No antibodies
Baby 2: IgG
Baby 3: IgM
Baby 4: IgM

A - Baby 1's mother had immunity to Rubella.
B - Baby 2 will have 2 years passive immunity.
C - Baby 3 got IgM through the placenta.
D - Baby 4 got infected with rubella during fetal development.

I chose D, as did most others.

Wow amazing memory lol
I really hope it is B though.. cause the babies immune system hasn't developed yet at that stage

[diam0nds]

It was something like this.

There are four newborns and their mothers when pregnant were infected with the rubella viruses. Antibodies IgM and IgG are produced by the mother. IgM cannot pass through the placenta. Babies haven't been fed.

Baby 1: No antibodies
Baby 2: IgG
Baby 3: IgM
Baby 4: IgM

A - Baby 1's mother had immunity to Rubella.
B - Baby 2 will have 2 years passive immunity.
C - Baby 3 got IgM through the placenta.
D - Baby 4 got infected with rubella during fetal development.

I chose D, as did most others.

how on earth did you remember that? haha I chose D too