Someone asked this question in your old video, however you might have missed answering it. So I thought it would be helpful if you could please answer it miss! the diagram on 11:11 at the top of the page suggests that the products of lipid digestion (monoglycerides and fatty acid) are emulsified into micelles, which makes sense because it forms the micelles which can be absorbed into the epithelial cell. However at the same time i believe you said emulsification/bile salt occurs before the lipase action/ lipid digestion to provide a larger surface area and faster hydrolysis by the lipase enzyme so does emulsification happen twice? first emulsification before chemical digestion so that triglycerides are covered in bile salt to become small droplets/vesicles of triglycerides (easier to become hydrolysed) and second emulsification after chemical digestion to make the products (monoglycerides and fatty acids and bile salt) into micelles too? and so what stage are the micelles formed? are they formed twice? (lipid --> small micelle lipid droplets to be hydrolysed) and (monoglycerides and fatty acids --> small micelle droplets with bile salt, monoglyceride and fatty acids) hope my question makes sense, sorry if its so wordy!
@@bethanyhopwood5480 Digestion: 1. Bile salts emulsify fats/lipids. Increase surface area for FASTER lipase action 2. Lipase hydrolyses fats/lipids into monoglycerides (or glycerol) and fatty acids 3. Hydrolysis of ester bonds (always mention type of bonds broken for any aqa Q) Absorption: you don't acc have to say how the micelles form (emulsification) just say what they contain 1. Micelles contain bile salt, monoglycerides and fatty acids and they: make MG and FA more soluble in water, carry MG and FA to lining of ileum (for absorption), maintain high concentration of MG/FA to cells lining the ileum 2. MG and fatty acids (are lipid soluble so) are absorbed into epithelial cells by diffusion 3. Triglycerides reformed (at SER if u wanted 2know) and are combined with proteins to form chylomicrons(@ Golgi) 4. Chylomicrons packaged into vesicles. Vesicles moved to cell membrane + fuses with it. Chylomicrons released via exocytosis. 5. Chylomicrons enter lacteals/lymphatic vessels and are eventually deposited in circulatory system (blood). I got these steps from a model answer and you probably won't need all of them at once but I memorised these and answered a bunch of past paper qs ad they hit every marking point! Lmk if you understand it!
