Katiesaliba's thread

[katiesaliba]

VCAA 2008 Q~

Question 5
Normally in mammals, if tissue from another individual enters the body, the foreign cells are recognised as
‘non-self’ by the immune system. The tissue is then rejected unless special drugs are used.

a. i. Which cells of the immune system are initially responsible for recognising non-self cells introduced
by an organ transplant?
 
ii. How do the cells you have named in part i. distinguish between self and non-self cells?
 

FOR THIS QUESTION, WHICH RECEPTORS DO THE CELLS USE TO DETERMINE NON-SELF? MHC II MARKERS?

Also, can macrophages engulf any kind of foreign cell, including human cells, or are human cells too big?

[Scooby]

The non-self cells in the transplanted tissue are destroyed by cytotoxic T cells (which recognise non-self peptides displayed on class I MHC molecules). The receptors on the cytotoxic T cells involved have to be complementary to these antigenic non-self peptides.

Phagocytes (eg. macrophages) can engulf human cells, which happens in necrotic tissue, for instance

[katiesaliba]

In phospholipids, is the glycerol component AND the ester linkage considered a part of the molecule's hydrophilic head? I know fatty acid tails are hydrophobic, but the ester linkage is hydrophilic, is it not?

[nhmn0301]

In phospholipids, is the glycerol component AND the ester linkage considered a part of the molecule's hydrophilic head? I know fatty acid tails are hydrophobic, but the ester linkage is hydrophilic, is it not?

I don't think VCCA gonna make a big fuse about this, but in general, I wouldn't say just the ester linkage by itself is soluble or not, it really depends on the attaching chain length, the longer the chain length, it will mask the effect of ester linkage. If it's not in the case of phospholipids (which has a pretty long chain length), but in the case of ethyl methanoate for example, than it's fairly soluble (again, pretty sure not examinable in Bio).

[vox nihili]

In phospholipids, is the glycerol component AND the ester linkage considered a part of the molecule's hydrophilic head? I know fatty acid tails are hydrophobic, but the ester linkage is hydrophilic, is it not?

nhmn0301 is right.

FYI: carboxyl group of fatty acid wouldn't be hydrophobic. The carbon tail is so large though that it's hydrophobic overall.

[katiesaliba]

Thanks! 
So glycerol would be the only part of the fat that would be included in the hydrophilic head?

[nhmn0301]

Thanks! 
So glycerol would be the only part of the fat that would be included in the hydrophilic head?

Glycerol is definitely in the hydrophilic head, but it's not the only thing. You also have a phosphate and choline that attached to the glycerol. It is these 3 structures that combine together and make the hydrophilic head. See image here: http://www.columbia.edu/cu/biology/courses/c2005/purves6/figure03-21.jpg

[katiesaliba]

For HIV patients, will HIV particle accumulation in lymph nodes cause the nodes to swell? Because that's where T-cells will be most abundant...?

[nhmn0301]

For HIV patients, will HIV particle accumulation in lymph nodes cause the nodes to swell? Because that's where T-cells will be most abundant...?

Yes, HIV typically causes lymph nodes swelling. There are 3 areas that are prone to develop enlarged nodes such as : head and neck, armpit and groin (pretty sure not examinable in VCE)

[vox nihili]

For HIV patients, will HIV particle accumulation in lymph nodes cause the nodes to swell? Because that's where T-cells will be most abundant...?

It may do, but that's not the reason for it. Remember, the particles accumulate inside the T-cells. It'll be the response to HIV or opportunistic infections that cause swelling.

[katiesaliba]

Is the probability of finding primer sequence of 20 nucleotides in another part of an individual's genome very high?

[vox nihili]

Is the probability of finding primer sequence of 20 nucleotides in another part of an individual's genome very high?

No.

[katiesaliba]

1.How exactly does reduced protein synthesis lead to cell death? Does it concern apoptosis or necrosis?
2. Why is rhesus factor irrelevant for kidney transplants?
3. Why is there still a risk of graft rejection if blood type, rhesus factor and HLP are all matching? Thanks!