VCE Biology Question Thread

[Biology24123]

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.

If the cell is abnormal then there might be a lower expression of MHC 1 proteins. Therefore, the NK cells will be activated to trigger apoptosis of the cell.

[The Usual Student]

just a curious thought i had,

What make a nucleic acid ... an acid? thanks!
they certainly don't donate protons, so BL definition is out.. or is it?

[TheAspiringDoc]

If the cell is abnormal then there might be a lower expression of MHC 1 proteins. Therefore, the NK cells will be activated to trigger apoptosis of the cell.

Oh deary-me  ; I forgot that extrinsic apoptosis was a thing and got it confused with necrosis!

Sorry for the confusion

P.S.

Spoiler

Wooooo 500 posts!!!!!

[TheAspiringDoc]

just a curious thought i had,

What make a nucleic acid ... an acid? thanks!
they certainly don't donate protons, so BL definition is out.. or is it?

the phosphate group in the nucleotides is related to phosphoric acid.

Edit: I believe the 'nucleotide bases' are actually basic btw?

[skybluemaniac]

the phosphate group in the nucleotides is related to phosphoric acid.

Edit: I believe the 'nucleotide bases' are actually basic btw?

I think the nucleotide bases have basic properties similar to a "weak base". Whereas the phosphate group acts somewhat similar to a "strong acid", thereby making the overall property acidic. Correct me if I'm wrong though!

[TheAspiringDoc]

notes say: 'phagocytosis is the endocytosis of large macromolecules or whole structures'. Other than things like say, bacteria, is there anything else that these 'whole structures' could be?

[vox nihili]

I think the nucleotide bases have basic properties similar to a "weak base". Whereas the phosphate group acts somewhat similar to a "strong acid", thereby making the overall property acidic. Correct me if I'm wrong though!

Pretty sure this is right. The phosphate is more acidic than the bases are basic; hence, overall acidic.

Cool question though.

notes say: 'phagocytosis is the endocytosis of large macromolecules or whole structures'. Other than things like say, bacteria, is there anything else that these 'whole structures' could be?

Cell fragments from dead tissue, extracellular matrix etc etc

[TheAspiringDoc]

What exactly does it mean when wikipedia says "The structure of the phospholipid molecule generally consists of two hydrophobic fatty acid "tails" and a hydrophilic "head", joined together by a glycerol molecule. The phosphate groups can be modified with simple organic molecules such as choline."

[vox nihili]

What exactly does it mean when wikipedia says "The structure of the phospholipid molecule generally consists of two hydrophobic fatty acid "tails" and a hydrophilic "head", joined together by a glycerol molecule. The phosphate groups can be modified with simple organic molecules such as choline."

BEYOND VCE

Phosphate groups in a phospholipid have two free -OH groups. These can react with different organic molecules, effectively attaching them to the phospholipid. The presence of these groups changes the function of the phospolipids. For instance, one phospholipid (phosphatidylserine) has the amino acid serine attached to the phosphate group; if this phospholipid is found on the outside of the plasma membrane, it serves as a signal of apoptosis thereby attracting phagocytes to engulf the cell.

[Callum@1373]

What exactly does it mean when wikipedia says "The structure of the phospholipid molecule generally consists of two hydrophobic fatty acid "tails" and a hydrophilic "head", joined together by a glycerol molecule. The phosphate groups can be modified with simple organic molecules such as choline."

So on the head of the phospholipid molecule in a membrane various groups can bond, commonly choline. Phosphate has two free alcohol groups which will react with the groups

[heids]

AspiringDoc, I swear you know more about Biology than I will ever know in my entire life. (as does everyone else on here tbh)

Come and take over my job

[TheAspiringDoc]

Cheers guys!

So on the head of the phospholipid molecule in a membrane various groups can bond, commonly choline. Phosphate has two free alcohol groups which will react with the groups

So it can form the bonds with the organic molecules but might not, and the phospholipid may just be topped off by the phosphate group?

AspiringDoc, I swear you know more about Biology than I will ever know in my entire life. (as does everyone else on here tbh)

Come and take over my job

haha thnx btw i don't though

[Biology24123]

BEYOND VCE

Phosphate groups in a phospholipid have two free -OH groups. These can react with different organic molecules, effectively attaching them to the phospholipid. The presence of these groups changes the function of the phospolipids. For instance, one phospholipid (phosphatidylserine) has the amino acid serine attached to the phosphate group; if this phospholipid is found on the outside of the plasma membrane, it serves as a signal of apoptosis thereby attracting phagocytes to engulf the cell.

(Image removed from quote.)

Are glycolipids formed this way

[Callum@1373]

Cheers guys!
So it can form the bonds with the organic molecules but might not, and the phospholipid may just be topped off by the phosphate group?
haha thnx btw i don't though

A phospholipid will always be "topped" off with a phosphate (hence the name), it's whether an organic group is bonded to the phosphate hydrophilic head, but I believe that's beyond VCE someone correct me?

[TheAspiringDoc]

A phospholipid will always be "topped" off with a phosphate (hence the name), it's whether an organic group is bonded to the phosphate hydrophilic head, but I believe that's beyond VCE someone correct me?

I think you may have misinterpreted my question. What I meant is, is there always an organic molecule bonded to the phosphate (other than the glycerol of course!)