Intro to lipids Flashcards Preview

Biochemistry MBS > Intro to lipids > Flashcards

Flashcards in Intro to lipids Deck (42)
Loading flashcards...
1

lipids

-hydrophobic organic molecules that can be extracted from cells by non-polar solvents
-associated with each other, excluding water

2

2 classes of lipids

-fatty acids
-isoprenoids

3

fatty acids

-amphipathic, micelle forming, soaps
-energy storage (fat dep to cushion organs and insulate)
-membranes (electrical insulation) including phospholipids and sphingolipids
-signals

4

isoprenoids

-bile acids/ salts
-membranes
-signals
-cofactors
-fat soluble vitamins

5

fatty acid nomenclature

-carboxyl carbon = 1
-FA symbol: # before colon = total length of chain
-at neutral pH, FA's are charged and act as soaps
-# after colon = number of double bonds
-superscript is the double bond start point, it then reaches to the subsequent carbon

6

stearic acid

18:0
-zero after colon representation full saturation

7

palmitic acid

16:0

8

alpha, beta, and omega

-alpha = first C after the carboxyl
-beta = second C after the carboxyl
-omega = last C of the chain

9

omega number

number of carbons from the terminal methyl to the nearest double bond

10

linoleic acid

-18:2
-9,12
-omega 6

11

arachidonic acid

-20:4
-5,8,11,14
-omega 6

12

linoleic and linolenic deficiency

-these are essential FA's
-symptoms: scaly dermatitis, alopecia (hair loss), thrombocytopenia (low platelet count), and cognitive development in children

13

triacylglycerols (TAGs)

-dietary and storage fats
-effectively formed by dehydration reactions between 3 FA's and glycerol
-fully hydrophobic

14

TAG nomenclature

-change the FA suffix from "-ic acid" to "-oyl"
-list by position before glycerol

15

what determines the physical properties of FA containing compounds

-melting point
-this is what will determine if they are solids or liquids at RT
-determines if membranes formed from FA containing compounds are fluid or semi crystalline
-MP increases with length

16

effects of tran saturation

-allows the FA's to pack more closely together
-natural foods have cis double bonds

17

leptin

-released by adipose tissue
-suppresses food intake by altering the hormones released by the hypothalamus
-leptin KO's are extremely obese

18

ghrelin

hunger hormone

19

percentage of fat in the typical US diet

-35-40% of caloric intake
-triglycerides are the major source

20

bile acids made from cholesterol in the liver are...

-converted to bile salts
-conjugated with glycine or taurine

21

gall stones

-imbalance of cholesterol, bile salt and phospholipid secretion

22

pancreatic lipases can not access hydrophobic fat droplets until

-emulsification happens
-gall bladder relases bile salts and phospholipids which get cleaved by pancreativ lipases
-these amphipathic molecules surround the TAG droplet and eventualy peristalsis makes them smaller
-these droplets with surrounding bile salts are called micelles

23

micelles form at

-critical micelle concentrationconcentration

24

hydrolysis of TAGs by pancreatic lipases

-TAG to diacylglycerol to monoacylglycerol
-full hydrolysis is not necessary, since the two hidroxyl groups on 2-MAG make is sufficiently soluble in water
-pancreatic lipase doesnt recognize olestra (FAs in ester linkages to hydroxyl groups on sucrose

25

pancreatitis

-deep recurrent moderate to severe abdominal, back, or epigastric pain exacerbated y alcohol
-nausea and vomiting
-steatorrhea in chronic cases
-elevated serum kipases and serum amylase
-300,000 cases a year, 20,000 die

26

steatorrhea

-lipid digestion disorders other than pancreatitis can cause this
-can be due to probelms with emulsification (biliary obstruction), lipolysis (pancreatic disease), or absorption by intestinal epithelia (celiac)
-causes intestinal discomfort, loss of essential FAs and fat soluble vitamins

27

micelles facilitate absorption

-free FAs and 2-MAG at CMC are passively absorbed by intestinal epithelia
-this reduces their concentration to below the CMC, and micelles break down to restore the CMC

28

bile salt recylcing

95% done through enterohepatic circulation

29

how to get FA's out of the epithelial cell

-resynthesize the TAG without CoA
-with CoA, the FA can not leave the epithelial cell

30

absorbing cholesterol esters

-hydrolysis of cholesterol esters to allow absorption
-resynthesis of CEs to drive absorption and prepare for transport