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Lipids Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is a lipid?

A

are heterogenous group of water insouble organic molecules that can be exacted from tissues

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2
Q

Why are lipid compartimentised?

A

Because of their insolublity in aqeuous solutions .

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3
Q

example of lipid that are compartmentised?

A

in the case case of
membrane-associated lipids or droplets of triacylglycerol in white
adipocytes, or transported in plasma in association with protein,

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4
Q

list some of the functions of lipids?

A

Structural components: membrane barrier

regulatory roles: vitamins and co- enzymes

inflammatory mediators: eicosanoids, prostaglandins, thromboxanes leukotrienes),

Steriod hormones : (corticosteroids),

second messengers (phosphoinositides, diacylglycerols)

Energy sources : 30-40 percent

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5
Q

What are the different classes of lipids?

A
  1. vitamin (A, K, D, E)
  2. phospholipids
  3. triacylglycerol
  4. fatty acids
  5. glycolipids
  6. Steriods
  7. sphingolipids
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6
Q

describe the structure of fatty Acids?

A

Amiphipathic : Pertains to a molecule containing both polar (water-soluble) and nonpolar (not water-soluble) portions in its structure.

> 90% of FAs in plasma as fatty acid esters (TAGs,
cholesteryl esters, phospholipids) in circulating
lipoproteins

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7
Q

Describe structure of a triglyceride?

A

contains a glycerol with 3 fatty acids

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8
Q

describe the structure of a phospholipid?

A
  1. in the extracellular matrix, there is an alcohol, diacyclglycerol or shingosine a phosphodiester linkage attached to a phosphate group.
  2. in the intracellular matrix there is a hydrophoic tail.
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9
Q

describe the structure of cholesterol?

A
  • cholestrol is found in the cell membrane where the, bulky steriod and the hydrocarbon tail is inside.\
  • the Oh group is on the outside where it can bind to other molecules as it serves as a site of attachment.
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10
Q

describe the amount of lipids that enter your body.

A
  • 90% are triglycerides
  • the remainder are cholesterol, free fatty acids and phospholipids
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11
Q

Lipid digestion occurs in which organs (order)

A
  1. mouth
  2. stomach
  3. small intestines
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12
Q

Describe digestion of lipids in the mouth?

A
  1. in the mouth the enzyme, lingual lipase is produced by the glands at the back of the tongue.
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13
Q

What does lingual Lipase targets.

A

lingual lipase targets TGA especially those with 12 carbons or less and break them down. for exampole milk in neonates.

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14
Q

lingual lipase is also seen in patients

A

with pancreatic insuffieciency such as cystic fibrosis where it break down TAGm despite the absence of pancreatic lipase.

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15
Q

describe lipid digestion in the stomach?

A
  • gastric lipase is introduced
  • lipids are not digested in adults until the small inestines .
  • the creation of chyme.
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16
Q

digestion of salts in the small intestines?

A
  1. done in the duodenum
  2. occurs by emulsification
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17
Q

what is emulsifcation?

A
  1. emulsification when the surface area of a hydrophobic lipid droplets are increase so that lipase can work efficiently.
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18
Q

Emulsification can occur in two process

A
  1. Bile salts: they have detergent properties.
  • bile is made in the liver and stored in the gall bladder.
  • derivatives of cholesterol linked to side chain of glycine or taurine via an amide linkage
  1. peristalsis
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19
Q

what is the structure of bile salt?

A

Glycine + bile acid

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20
Q

what is the function of bile salts?

A

function to stabilize lipids by preventing coalescing and making smaller particles thus increasing surface area for digestion by lipase

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21
Q

cholic acid is added to glycoholic acid & taurocholic acid by

A

amide group.

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22
Q

what is a miscelle?

A

Micelles are clusters of amphipathic lipids that coalesce with hydrophobic sides inside and hydrophilic heads outside

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23
Q

Describe the breaking down of dietary fat

A
  1. Bile salt emulsy fat into smaller conponents called lipid emulsion
  2. lipase acts on the lipid emulsion to form 2- monoglyceride + 2 fATTY ACIDS
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24
Q

HOW IS A MIXED MISCELLE FORMED?

A

2- MONOGLYCERIDE & 2 FATTY ACIDS REASSCOIATE WITH BILE ACIDS T FORM MIXED MISCELLE

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25
Q

Secretion of pancreatic enzymes are under the control of?

A

Hormones

26
Q

Triacylglcerol degration

A

Triacylglycerides are too large for degradation so they must be broken down by pancratic lipase which removes the fatty acids at C-1 and C 3 to form _2- monoacylglycerol and free fatty acids. _

27
Q

What is Colipase?

A
  1. Secreted by the pancreas
  2. anchors and stablises lipase to the lipid droplet at the lipid aqeous interface.
  3. helps lipase overcome inhibiiton by bile acids.
28
Q

what is the role of cholesteryl ester hydrolase?

A

it cleaves cholesterol esters to cholesterol and free fatty acids

29
Q

function of Phospholipase A2

A
  • Secreted by pancreas and it aids in the removal of Fatty acids at carbon 2 to form lysophospholipid.
30
Q

phospholipase A2 is activated by

A

trysin

31
Q

Lysophospholipase functions to?

A

remove fatty acids at carbon 1

32
Q

Cholecystokinin

A
  1. it degrade lipids and is secreted in response to lipids
  2. CCk is secreted in response to the duodenum and jejunum mucosal cells
  3. acts on the gall bladder to secrete BILE
  4. it acts on the exocrine cells of pancreas to release digestive enzymes
33
Q

function of secretin

A
  1. peptide hormone secreted by other intestinal cells
  2. stimulates the pancreas to secrete bicarbonate in order to neutralise of the intestinal contents to aid enyme activity.
34
Q

there are 5 pancreatic enzymes. what are they?

A
  • pancratic lipase
  • colipase
  • cholesterol esterase
  • phospholipase A2
  • lysophospholipase
    *
35
Q

absorption of lipids by intestinal mucosal cells

A
  • after lipid digestion. miscelles approach the brusher border of intestinal mucosal cells and release contents which are absorbed.
    *
36
Q

which types of lipid chains do not need to be transformed into miscelles.

A

short and medium

37
Q

what is the fate of bile salts?

A

bile salts are reabsorbed in the ilieum, transported to the liver and finally recycled and secreted back to the digestive tract.

38
Q

where is pancreatic lipase produced and whta is its site of action?

A

Pancreas and the site of action is small intestines

39
Q

what is it special property of pancreatic lipases

A

it require cholipase fpr stabilisation

40
Q

what is the origin and site of action for lipoprotein lipase?

A

extrahepatic tissues and surface of endothelial cells lining the cepillaries

41
Q

what is the function of lipoprotein lipase?

A

degrades triacyclglyecerls circulating in chylomicrons or VLDL , releasing non- esterified fatty acids and glycerol.

42
Q

reassembly of lipids in enterocytes

A
  1. fatty acids in miscelles are activated to form fatty acyl CoA.
  2. Fatty acyl Co A is reesterified to form TGA, cholesterol esters, phosphlipids
  3. assembly in the ER to form Chylomicrons
  4. chylomicrons secreted through lacteals into lymph, thoracic duct, left subclavian vein.
43
Q

where does a mixture of lipids absorbed by enterocytes migrate

A

to the Er where biosynthesis of complex lipids occurs

44
Q

long chain fatty acids are activated by which enzyme?

A

fatty acyl Co A synthase ot thiokinase to form fatty acyl - Co A

45
Q

what happens to short chain fatty acids in the intestinal mucosa cells?

A

they are taken by serum albumin to the liver

46
Q

what happens to lysophoshlolipids in the intestinal cells?

A

they are converted to phosholipids

47
Q

what happens to cholesterol in the intestinal mucosa

A

converted to cholesterol esters.

48
Q
A
49
Q

what is chyle?

A

lymph with new digested and absorbed lipids ( have milky appearance)

50
Q

whta is the function of Apo C- 11

A

to activate capillary lipoprotein lipase

51
Q

what is the function of apo E

A

mediates uptake of chylomicrons remnants in the liver.

52
Q

chylomicrons must have which apo protein to enter the leave the liver?

A

APO 48

53
Q

a deficiency that causes a build up of chylomicrons in the blood

A

congenital A lipoproteinemia cause by a deficiency in Apo B - 48

54
Q

What are nascent chylomicrons?

A

chylomicrons entering the lacteal from the enterocytes

55
Q

When are mature chylomicrons formed?

A

when the nascent chylomicrons leave the lacteal and enter the circulation and needs ApoE and Apo c- ii.

56
Q

what causes mature chylomicrons to become chylomicron remenant

A

lipoprotein lipase

57
Q

Type III hyperlipoproteinemia

A

when mylomicron remnants can not be removed from the plasma doe to defiency of APO E

58
Q

Lipoprotein Lipase

A

from muscle and adipocyts, digests triaglycerol,

they are anchored in the endothelial on the interior of blood vessels.

59
Q

the fate of FFA

A
  1. FFA may be transported by serum albumin to tissure where cell oxidise them for energy
  2. adipocytes may re- esterify to form TAG for storage until FFA are reuired by tissues
  3. FFA enter adjacent muscle or adipocytes
60
Q

Fate of glyccerol

A

Glycerol is transported to the liver and converted to glycerol 3 phosphate for glycosis or gluconeogensis.

Glycerol kinase is only in the liver.

61
Q

Lipid Malabsportation

A

results in loss of lipids, fat- souble vitamins and essential FA

Steatorrhea

62
Q

What common cause of steatorrhea?

A

defective bile secretion

defective pancreatic enxyme secretiion

inablity of intestinal mucosal cells to absorb lipid

Cell Biology (13 decks)

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