24 Flashcards
Two examples of molecules associated with fat metabolism
- Triacylglycerol (has a 3 carbon glycerol back bone component, 3 lipid long chain fatty acid units (vary in chain length) - esterified to glycerol backbone - acyl functional group )
- Cholesterol ester (4 carbon rings with carbon structure extension, ester variant version shown, R represents a long carbon chain, cholesterol is often eaterified to various long chain fatty acids
What sulbuises fat in the GI tract?
Bile acids (bile salts) solubilize fat in the gastrointestinal tract
(- facilitates the breakdown of tryirsalgylceral into fatty acids and a glycerol derivative component do it can be taken into the body)
Fat molecules are not typically
Soluble (unless highly modified with charged groups)
One side of a bile salt is _____ the other side is _____
Hydrophilic
Hydrophobic
What are bile salts synthesised from and where are they synthesised and then where are they stored and as what are they stored as?
synthesised from cholesterol in liver and stored in gall bladder as bile
Where are bile acids/salts secreted into and in response to what
Secreted into small intestine in response to cholecystokinin
Bile acids/salts are powerful ________ with _______ and ______ surfaces
Are powerful detergents with hydrophobic and hydrophilic surfaces
(Biphasic)
What do bile acids form and why?
Form micelles with triacylglycerols to increase surface area for digestion
(Micelles - hydrogphob core and external surface is hydrophilic )
What does bile contain
Water
Bile acids
Electrolytes
Phospholipids
Cholesterol (= Gall stones)
Bile pigments ie bilirubin, biliverdin - breakdown of haem, recycled via liver)
If cholesterol too high
Gall stones - insoluble
How bile acids are made from cholesterol - diagram
Hydroxyl group at the end of cholesterol…
… could in some cases by esterirfied with varies chain length fatty acids to make a cholesterol ester
Bile salts all vary in terms of their…
…functional groups
Two random examples of bile acids
- glycocholic acid
- taurocholic acid
(Drriviates of basic choletestol building block)
Where is bile synthesised ?
In the liver
Where is bile stored?
Gall bladder
What is the image of
( - higher cholesterol input into the diet = posibility for forming insoluble inclusion bodies )
Gall stones
Digestion is regulated by?
Peptide hormones
Examples of peptide hormones (short amino acid sequences)
What hydrolyses triacylglycerols to free fatty acids and 2-monoacylglycerol
Pancreatic lipase
What does Pancreatic lipase do
Pancreatic lipase/colipase system hydrolyses triacylglycerols to free fatty acids and 2-monoacylglycerol
Pancreatic lipase/collipase enzyme system hydrolyses triacylglycerols to free fatty acids and 2-monoacylglycerol - diagram, what does R1, R2 and R3 mean
What forms after Pancreatic lipase/collapse enzyme system hydrolyses triacylglycerols to free fatty acids and 2-monoacylglycer (absorbtion)
Smaller micelles form containing bile salts, free fatty acids, monoacylglycerol (and cholesterol)
Micelles are absorbed across intestinal cell membrane
What do we need to enhance activity of lipase
Co-lipase
2-monoacylglycerol
1 fatty acid chain
Bile salts solubilize triacylglycerols and assist with hydrolysis
- DIAGRAM - plus yappage
Once in micelle, pancreatic lipase can interact with other molecules and project in the catalytic active site of enzyme enabling hydrolysis of triaglycerol inside this structure
(Need to be hydrolysed to be taken into the epithelial cells to then by transported into and around the body)
Absorption of products from the gastrointestinal tract into the bod - what features of the intestine assist with the absorbtion
The small intestine has specialised structures that create a vast surface area for absorption.
Villi
Microvilli (brush border)
(Both increase SA)
(All molecules not just lipids are absorbed here)
How Xenical (Orlistat) accts as an inhibitor of pancreatic lipase
- compound acts as an inhitibotr by covaletnly bonding to a functional group neat the lipase active site thus blocking the lipase active site
Overview of lipid processing in the gastrointestinal tract
- diagram
BILE SALTS ARE REABSORBED AND RECYCLED TO THE LIVER
- FA are put back into TG for transport ?? Into chylomicros then into the blood and circled around the body)
General lipoprotein structure
- phospholipids/proteins have hydrophilic head and hydrophobic tails
Once fatty acid and MG has been transported across the epithelial tissue… its put back into triaclyglycerol so that they can by put into the chylomicorns for shipping- what does triaclyglycerol synthesis look like?
- progressive addition of fatty acids onto strucuture forming tryclyglycerol
- fatty acids are activated with CoA to achieve the reaction sequence
- occurs in the epithelium
- going down the table
- going down the table desensitised increases
- TAG decreases down the table (TAG is low density)
- protein increases
How can lipoprotein composition be analysed?
Lipoprotein composition in clinical plasma samples can be analysed by native (non-denaturing) gel electrophoresis
A densitometry scan of the lipoprotein gel provides another way of comparing normal vs. abnormal lipoprotein profiles
Blood lipid profile - what do labs typically measure -
Typically, labs measure total cholesterol, high density lipoprotein (HDL) and triglycerides (triacylglycerols) – used to identify dyslipidemia
How can LDL be measured
Low density lipoprotein (LDL) can be estimated from [total cholesterol – HDL – triglyceride/5], but different calculation methods give different results
- will b in exam
Wtf is this diagram
Inherited lipid disorders
Xanthomas in FH patients
Fatty growths under the skin
