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Cell Bio > Energy Metabolism- Lipids > Flashcards

Energy Metabolism- Lipids Flashcards

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Biology 101 flashcards
1
Q

Lipids

A

heterogeneous group of water-INsoluable organic molecules;
vitamins A,D,E,K;
major source of E for body;
provide hydrophobic barriers (compartmentalization);
hydrophobic so are found in compatmentalized form (membrane lipids) or bound to plasma proteins (lipoproteins, albumin)

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2
Q

Common lipids

A

fatty acids, triacylglycerol, phospholipid, steroid, glycolipid

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3
Q

Amphiphatic character

A

hydrophobic and hydrophilic sides

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4
Q

Molecules with high physiological relevance

A

prostaglandins, steroid hormones

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5
Q

Dietary lipids

A

cholesterol esters, phospholipids, fatty acids

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6
Q

Lipid digestion: beginning

A

starts in the stomach (lipases are acid-stable)

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7
Q

Lipid structure

A

hydrophobic hydrocarbon chain: CH3(CH2)n

hydrophilic carboxyl group: COO-

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8
Q

Lipid digestion: emulsification

A

occurs in duodenum;
breaks lipids so lipase can “eat” the cells;
bile acids emulsify fat droplets

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9
Q

Lipid digestion: control

A

CCK (cholecystochinin) stimulates pancreas–> pancreas enzyme secretion
CCK stimulates gall bladder–> bile acid secretion
Secretin stimulates pancreas to make morebicarbonate

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10
Q

Long chains

A

digestion produces free fatty acids (FFA), cholesterol, and 2 monoacylglycerol (MAG) which form long chains (micelles)

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11
Q

Short and medium chains

A

directly released to portal circulation where they bind to albumin

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12
Q

Mixed micelles

A

lumen of small intestine; long chains

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13
Q

Chylomicron

A

a lipoprotein; generated in ER;
so big it can’t go to capillaries so bypasses portal vein and liver; goes to lymphatic system–>renal system;
directly sends lipids to body (bypass liver);
gets FFA’s–> used up by muscles for E;
gets glycerol–>sends to liver to make G3P–>gluconeogenesis

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14
Q

Re-esterification

A

once absorbed, lipids go to ER for synthesis:
MAG–>TAG
Lysophospholipids–>phospholipids
Cholesterol–>fatty acids

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15
Q

Composition of plasma lipoproteins

A

triacylglycerol, protein, phospholipids, cholesterol (used for hormones), and cholesteryl esters

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16
Q

Use of dietary lipids by tissues

A

TAGS from chylomicrons: free fatty acids used by muscles for E, fat cells storage, in blood bind to plasma
TAGS from chylomicrons: glycerol sent to liver to make G3P
Chylomicron remnants absorbed by liver by process receptor-mediated endocytosis

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17
Q

Relevance of fatty acids

A

E: during fast, FA’s bind to albumin leading to oxidation
Structural: phospholipids and glycolipids in the plasma membrane
Hormone precursor: prostaglandins
E reserve: TAG in adipose tissues

18
Q

Structural aspects of lipids: Saturated

A

no double bonds

19
Q

Structural aspects of lipids: Unsaturated

A

double bonds (kinks)

20
Q

Structural aspects of lipids: Configuration

A

double bonds more frequent in CIS configuration

cis has important role in membrane

21
Q

Phospholipids: structure

A

two fatty acid chains (one saturated, one unsaturated)
phosphate group
alcohol group
substituent
unsaturated more important bc makes more flexible membrane

22
Q

Fatty acids of physiological relevance

A

Glycerine, phosphoglyceride, sphingomyelin;
Number of carbons=double bonds and positions
alpha: carboxyl group
beta: carbon 3
gamma: carbon 4
omega: terminal methyl group

23
Q

Essential FA’s

A

cannot be synthesized in body- we must eat them!
linoleic acid (w-6 FA)–> arachodonic acid
alpha-linoleic acid (w-3 FA)–> growth & development

24
Q

De novo synthesis

A

rxn occurs in cytosol;
need acetyl CoA to make citrate (in mitochondria), citrate gets pumped into cytosol;
result is palmitate (fully saturated fatty acid)

25
Q

De novo synthesis enzyme

A

acetyl CoA carboxylase: takes acetyl CoA & makes malonyl CoA, is a rate limiting step;
fatty acid synthase makes rest of synthesis occur

26
Q

Use of new fatty acids

A

store (in fat cells) or mobilize (use enzyme hormone sensitive lipase);
storage simulated by INSULIN

27
Q

Hormonal regulation of fat degradation in adipocyte

A

glycerol released during TAG degradation CAN’T be metabolized by adipocytes (they lack enzyme glycerol kinase)–> transported to liver;
free FA’s bind in blood to albumin and are transported to tissue used for E in mitochondria

28
Q

Beta-oxidation

A

occurs in mitochondria;
how make E from fatty acids;
takes C from fatty acid (palmitoyl CoA) to produce 8 ACoA, 7 NADH, 7 FADH2;
carrier that transports C’s (from fatty acids) into mitochondria: the carnitine translocase;
from there generates NET 129 ATP

29
Q

Beta-oxidation net gain

A

129 ATP

30
Q

Ketone bodies

A

important source of E during fasting;
high levels lead to acidosis;
LIVER

31
Q

Ketone bodies synthesis

A

liver (mitochondria) can convert ACoA into ketone bodies such as acetoacetate, 3-hydroxybutyrate, and acetone;
in peripheral tissues, can be converted into ACoA which enters TCA;
SO, synthesis in liver and use in peripheral tissues

32
Q

Synthesis of phosphlipids for the plasma membrane occurs…

A

in the smooth ER

33
Q

Fatty acids of physiological relevance

A

hydrophilic (polar) head, hydrophobic tail;

glycerophospoholipids

34
Q

orientation of phospholipids in aqueous milieu

A

lipid-bilayer: hydrophobic tail in, polar head out

liposom: wheel formation, water inside and outside, polar heads facing out towards water (bc they’re hydrophilic)

35
Q

Synthesis of phospholipids

A

all cells EXCEPT ERYTHROCYTES (RBC’s) can synthesize phospholipids;
occurs in sER, goes to golgi apparatus, then membranous organelles;
donation of phosphatidic acid from CDP-DAG to an alcohol

36
Q

Glycerophospholipids

A

phosphatidic acid + alcohol;
serine + PA = phosphatidylserine
ethanolamine + PA = phosphatidylethanolamine (cephalin)
choline + PA = phosphatidylcholine (lecithin)
inositol + PA = phosphatidylinositol
gylerol + PA = phosphatidylglycerol

37
Q

Cardiolipin

A

phospholipid of physiological relevance;
inner mitochondrial membrane;
maintenance for e- transport chain

38
Q

Platelet-activating factor (PAF)

A

phospholipid of physiological relevance;
activates inflammatory cells, platelet aggregation;
cause anaphylactic reactions

39
Q

Sphingomyelin

A

phospholipid of physiological relevance;

component of myelin in nerve fibers

40
Q

Role of inositol triphosphate (IP3) and diacylglycerol (DAG) in intra-cellular signaling

A

hormone is 1st receptor in step 1

IP3 & DAG are 2nd messengers in step 5

41
Q

Blood typing

A

ABO blood group antigens are GLYCOSPHINGOLIPIDS

sphingosin

42
Q

Prostaglandins & Thromboxanes

A

play many roles in physiology;

synthesis: eicosanoids; eicosa= 20 carbons

Cell Bio (4 decks)

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