AQA biology ISA on digestion of triglycerides.

After reading around on the internet looking for help on this ISA and finding nothing... i have put together a little revision thing. I have done the experiment and am sitting the paper tomorrow so lets hope this helps me.

- Glycerol + 3 Fatty acids = Triglyceride + 3 H2O

- Each Fatty acid forms a bond with the glycerol in a CONDENSATION reaction. HYDROLYSIS of a triglyceride therefore produces glycerol and 3 fatty acids.

- The fatty acids in the triglyceride determine its properties/function whatever. There are over 70 fatty acids and they all have a carboxyl group (-COOH)

- No C=C bonds = unsaturated
- 1 C=C bond = Mono-unsaturated
- 2+ C=C bonds = Poly-unsaturated

- TEST FOR LIPIDS
Dissolve substance in ethanol
add water
cloudy white colour indicates the presence of a lipid. This is due to the lipid being finely dispersed in the water to form an emulsion. the light refracts when going through droplets of oil then through droplets of water giving the cloudy appearance.

- BILE SALTS
- Bile helps emulsify the fats in food
- they surround droplets of fat which prevents the fat reforming into larger molecules
- this provides a larger surface area for the lipase to digest the triglycerides and the lipase can get to the fatty core through gaps between bile salts.
- therefore the times recorded for the colour change should be faster with the bile salts and lipase because the bile salts aid the digestion. Times should be slower for lipase alone.

- PHENOLPHTHALEIN (pink indicator used)
This is pink in alkaline solutions (bile is alkaline) and turns colourless below pH 8.3.
____in this experiment the milk used probably had added alkaline to make the solution pink in the first place because milk has a natural pH of about 6.5 and would normally be colourless.
Anyway...fatty acids produced from the hydrolysis of triglycerides cause a change in pH causing the colour to change from pink to colourless.

With regards to the boiled lipase and boiled bile salts, the boiled bile salts are just as efficeint as unboiled bile salts as they do not function by enzyme action and therefore are not denatured. (i think... )

The boiled lipase will not work as it is an enzyme and is denatured. the high temp breaks hydrogen and other bonds in the enzyme molecule causing the active site to change shape therefore the enzyme-substrate complex cannot be formed. ect ect. thats why the solution does not go colourless it stays pink.

Miss also said we should revise the effects of fats on health soooo.....

Triglycerides, are major components of low-density lipoproteins. low-density lipoproteins (LDL) are a type of lipoprotein made by the liver. they enable fats and cholesterol to move within the water-based solution of the bloodstream. Various tissues then release triglycerides to be used as a source of energy.

Low density lipoproteins carry cholesterol from the liver to other cells in the body.
High density lipoproteins transports cholesterol to the liver from other cells in the body.

ATHEROMA
Atheroma is a fatty deposit that forms within the walls on an artery. It begins as fatty streaks that are accumulations of white blood cells that have taken up LOW DENSITY LIPOPROTEINS.They bulge into the lumen of the artery causing it to narrow so that the blood flow through it is reduced. Atheromas increase the risk of two potentially dangerous conditions: thrombosis and aneurysm.

THROMBOSIS
If an atheroma breaks through the lining of the blood vessel it forms a rough surface that interrupts the otherwise smooth flow of blood. This may result in the formation of a blood clot in the condition known as thrombosis. This thrombus may block the blood vessel preventing the supply of blood to the tissues beyond it. The region of tissue deprived of blood often dies as a result of the lack of oxygen, glucose and other nutrients that the blood normally provides. Sometimes the thrombus is carried from its place of origin and lodges in and blocks another artery.

ANEURYSM
Atheromas that lead to the formation of a thrombus also weaken the artery walls. These weakened points swell to form a balloon blood filled structure called an aneurysm. These frequently burst leading to haemorrhage and therefore loss of blood to the region of the body served by that artery. A brain aneurysm is known as a stroke.

MYOCARDIAL INFARCTION
Heart attack results from a blockage in the coronary arteries. If this occurs close to the junction of the coronary artery and the aorta the heart will stop beating because its blood supply will be completely cut off. If the blockage is further along the coronary artery the symptoms will be milder because a smaller area of muscle will suffer oxygen deprivation.

idk if there is any other health risks associated with triglycerides but i cba doing any more.

lets hope i dont get an E in this again after all this revision

hope this helps!

Reply 1

priyafr

That REALLY helps!
Thank you so much!

I got a U last time :frown:

I hope I can manage to bet a B!
Thanks again!

Thanks a lot m8

Brilliant! Great to know someone is willing to put the effort in to help everyone out. Took me a lot of time to find the information that related exactly to what I needed it for and this was it. Helped a lot. Well done

AQA biology ISA on digestion of triglycerides.

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