Biochem lec 3 - Lipid Metabolism - Metabolism of dietary lipids

Question 1

characteristics of lipids

Answer 1

heterogenous group of water insoluable (hydrpophobic) organic molecules

major source of energy

Question 2

where does digestion of lipids begin and what is it catalyzed by

Answer 2

begins in stomach
catalyzed by lipase (an acid stable enzyme)
triacylglycerols (TAGS) are the primary targets

Question 3

where does emulsification of dietary lipids (fats) occur?

Answer 3

small intestine (duodenum)
increases the surface area of the hydrophobic lipid droplets so that digestive enzymes can act effectively

Question 4

fats are carried out of the small intestine by what

Answer 4

bile salts (hydrophillic points out, hydrophobic will interact w fat)

Question 5

which pancreatic enzyme degrades TAG

Answer 5

pancreatic lipase

Question 6

which pancreatic enzyme degrades cholesterol esters

Answer 6

cholesterol esterase
(cholesterol esters to cholesterol and free FAs)

Question 7

which pancreatic enzyme degrades phospholipids

Answer 7

phospholipase A2 and lysophospholipase

Question 8

where does degradtion of dietary lipids occur

Answer 8

in the pancrease by pancreatic enzymes

Question 9

what is too large to be taken up efficiently by the mucosal cells of the intestinal villi

Answer 9

triacylgercol, therefore acted upon by pnancreatic lipase

Question 10

most dietary cholesterol is present in what form

Answer 10

free form (nonesterified)

Question 11

what does phospholipase A2 do

Answer 11

removes 1 FA from C2 leaving a lysophospholipid

Question 12

what does lysophospholipase do

Answer 12

remove the FA at C1 leaving a glycerophosphoryl base

Question 13

how does cholecystokinin have hormonal control of lipid digestion in the small intestine

Answer 13

stimulates the release of bile and pancreatic enzymes

Question 14

how does secretin have hormonal control of lipid digestion in the small intestine

Answer 14

secretin stimulates bicarbonoate and water
(helps w synthesis of fatty acids)

Question 15

what do lipids along w bile salts and fat soluble vitamins form

Answer 15

mixed micelles
(disk shaped clusters of amphipathic lipids that coalesce with their hydrophobic groups on the inside and their hydrophilic groups on the outside

Question 16

what is the primary site of lipid absorption is where of the enterocytes

Answer 16

brush border membrane

Question 17

another name for intestinal mucosal cells

Answer 17

enterocytes

Question 18

the mixture of lipids absorbed by the enterocytes are synthesized to complex lipids in what location?
(resynthesis of TAG and cholesteryl esters occurs where)

Answer 18

in the ER

Question 19

lipid malabsorption can result in what

Answer 19

steatorrhea (lipid in the feces)

Question 20

what is lipid malabsoprtion/steatorrhea caused by?

Answer 20

disturbances in lipid digestion/absorption

Question 21

newly resyntheiszed TAGS and cholesterly esters are very hydrophobic or hydrophilic, and therefore aggregate in what type of environments

Answer 21

very hdrophobic, aqueous environments

Question 22

lipid droplets (chylomicrons) are surrounded by
and this increases or decreases the solubility of the droplet particle

Answer 22

-phospholipids
-unesterified cholesterol
-apolipoprotein
increases the solubility

Question 23

chylomicrons are released by what from what into the lacteals

Answer 23

exocytosis from enterocytes

Question 24

what are lacteals

Answer 24

lacteals are lymphatic vessels originating in the villi of the small intestine

Question 25

chylomicrons follow the lympatic sytem then enter what

Answer 25

the blood

Question 26

after chylomicrons enter lymph, ___

Answer 26

they enter the blood TAGs are drawn off by muscle and fat cells then chylomicrons remnants are removed from the blood by the liver

Question 27

TAGs contained in chylomicrons are broekn down primarily where

Answer 27

in capillary beds of skeletal muscle and adipose tissue

Question 28

lipoprotein lipase

Answer 28

break down TAG, attach to the line surface in blood vessels/capillaries so it can be taken by cells (degrades circulating triglycerides in the bloodstream)

Question 29

Hormone sensitive lipase -

Answer 29

breaks down TAG to drain storage (regulates lipid stores in adipocytes and steroidogenic tissues)

Question 30

fatty acids

Answer 30

-directly taken up by muscle cells and adipocytes -travel in blood until taken up by cells -produce energy in some cells -stored as TAGs in some cells

Question 31

glycerol used almost exclusively by what to do what

Answer 31

by liver to produced glycerol-3-phosphate which can enter glycolysis or gluconeogenesis by oxidation to DHAP

Question 32

remaining chylomicron components taken up by what

Answer 32

by liver and hydrolyzed to their component parts some can be recycled by the body