Lipids Flashcards by Michael Casimiro

Group of compounds insolublt to water, soluble in nonpolar solvents such as ether and chloroform

Lipids

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Lipids are transported in the vlood via_____

Lipoproteins

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Fats and waxes are classified under what type of lipids

Simple lipids

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What classification of lipids include the ff:
Phospholipids
Glylipids
Lipoproteins
Sulfolipids
Aminolipids

Complex lipids

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What classification of lipids includes the ff:
Fatty acids
Glycerol
Steroids
Ketone bodies
Hormones
Fat-soluble vitamins and micronutrients

Precursor and derived lipids

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Long chain of carboxylic acids

Fatty acids

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Identify fatty acid

Predominant fatty acid in coconut oil

Lauric acid

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Identify fatty acid

Structure is 12:0

Lauric acid

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Identify fatty acid

End-product if mammalian FA synthesis

Palmitic acid

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Identify fatty acid

Structure: 16:0

Palmitic acid

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Identify fatty acid

Predominant FA in olive oil

Oleic acid

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Identify fatty acid

Structure 18:1 (9)

Oleic acid

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2 essential fatty acids

Linoleic acid 18: 2 (9,12)

Linolenic acid 18:3 (9,12,15)

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Identify fatty acid

Precursor of prostaglandins, derived from linoleic acid

Arachidonic acid

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Identify fatty acid

Structure: 20:4 (5,8,11,14)

Arachidonic acid

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Dietary fatty acid
By-product of the saturation of fatty acid during hydrogenation or “hardening” of natural oils in the manufacture of margarine

Trans fatty acids

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Dietary fatty acid

Increased risk for coronary heart disease, prostate CA and colon CA

Saturated fatty acids

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Dietary fatty acid
Has anti-inflammatory properties
Supress cardiac arrhythmias, reduce serum TAGs, decrease the tendency for thrombosis, lower blood pressure
Decreased risk for CHD
Sudden cardiac death

Omega 3 FA

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Dietary FA
Provide arachidonic acid which is an important precursor of prostaglandins and leukotrienes
Decreases risk for CHD

Omega 6 FA

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Activated form of FA that participate in metabolic processes

Acyl CoA

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Enzyme for activation of FA prior to its participation in metabolic processes

Fatty acyl CoA synthetase

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Site of FA activation

Cytosol

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Pathway for synthesis of FA, specifically palmitate

Lipogenesis

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Site of lipogenesis

Liver, kidney brain, lung, mammary gland, adipose tissue

Cytosol

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Immediate substrate for lipogenesis

Acetyl CoA

Product of Lipogenesis

Palmitoyl CoA

Rate-limiting step for lipogenesis

Acetyl CoA + HCO3- + ATP —> Malonyl CoA | Enzyme: Acetyl CoA carboxylasa

Mitochondrial acetyl CoA (from the oxidation of pyruvate) is transported to the cytosol using _____ shuttle

Citrate shuttle

Identify enzyme: | Citrate —> acetyl CoA + OAA

ATP citrate lyase

Identify enzyme | Acetyl CoA—> Malonyl CoA

Acetyl CoA carboxylase

In the elongation of FA to palmytoyl CoA, ____ is used as a primer All subsequent carbon units are added via _____

Acetyl CoA | Malonyl CoA

Sequence of steps that are repeated seven times in elongation to palmitoyl CoA

Condensation—> Reduction —> Dehydration —> Reduction

______ is required as donor of reducing equivalents in the reduction reactions in the elongation to palmitoyl CoA

NADPH

3 substances/Pathways that serve as sources of NADPH in lipogenesis

Pentose phosphate pathway Malic enzyme Isocitrate dehydrogenase

Site of further elongation and desaturation of FA in lipogenesis

Smooth endoplasmic reticulum

Reaction in lipogenesis in which double bonds up to carbon 9 are introduced

Desaturation

Fatty acids are stored as _____

TAG

TAGs are synthesized by Sequential addition of _______ to glycerol-3-phosphate Removal of _______ Addition of _______

2 fatty acyl CoA Phosphate 3rd fatty acyl CoA

2 sources of glycerol-3-phosphate

DHAP from glycolysis by enzyme GA3P DH (liver and adipose) | Phosphorylation of free glycerol by glycerol kinase (liver)

During fasting, stored fat is hydrolyzed to release _____ | And 3 _____ by enzyme _______

Glycerol FA Hormone-Sensitive lipase

Hormone-sensitive lipase is activated by (increase/decrease) in the ff: Insulin Epinephrine Cortisol

Decrease Increase Increase

During fat mobilization, FAs are remived from which carbons in TAG form

Carbon 1 and/or carbon 3

Phosphorylation/dephosphorylation | Insulin

Dephosphorylation

Phosphorylation/dephosphorylation | Glucagon

Phosphorylation

Phosphorylation/dephosphorylation | Epinephrine

Phosphorylation

Phosphorylation/dephosphorylation | TAG breakdown

Phosphorylation

Pathway for the removal of acetyl CoA freagments from the ends of FA, also yielding NADH and FADH2

Beta oxidation

Acetyl CoA produced from Beta oxidation enters what pathway

Citric acid cycle

NADH and FADH2 produced from beta oxidation can enter what pathway

ETC

Site of beta oxidation

Mitochondria

Site of fatty acid activation

Cytosol

Beta oxidation occurs in what tissues

Muscle and liver | Tissues that use fatty acids as energy source

Substrate for beta oxidation

Palmitate

3 products of beta oxidation

8 acetyl CoA 7 NADH 7 FADH2

Rate-limiting step for Beta oxidation and enzyme

Translocation of fatty acyl CoA from the cytosol to the mitochondria Enzyme Carnitine-palmitoyl transferase

Enzyme for the rate-limiting step of beta oxidation

Carnitine-palmitoyl transferase

Steps of beta oxidation: | _______ activates fatty acid

Fatty acyl synthetase

Steps of beta oxidation: | _______ attaches fatty acyl to carnitine in the outer mitochondrial membrane

Carnitine acyltransferase 1

Steps of beta oxidation: | _________ is shuttled through the inner membrane

Fatty acyl-carnitine

Steps of beta oxidation: | ______ transfers fatty acyl group back to a CoA in the mitochondrial matrix

Carnitine acyltransferase 2

Sequence of steps repeated seven time in fatty acyl coa degradation

OHOT | Oxidation - hydration - oxidation - thiolysis

4 enzymes collectively known as fatty acid oxidase

Fatty acyl coa dehydrogenase /\2 enol CoA hydratase 3 hydroxyacyl CoA dehydrogenase Thiolase

Total ATP yield of palmitate

106 7 NADH (2.5 ATP each) 7 FADH2 (1.5 ATP each) 8 acetyl CoA (10 ATP each) Activation (-2)

Oxidation of FA with odd number or carbon atoms will yield ____ and ____

Acetyl CoA and propionyl CoA

In oxidation of odd chain fatty acids, propionyl CoA is converted into ______, a TCA imtermediate

Succinyl CoA

2 sequential enzymes in oxidation if odd chain fatty acids

Propionyl CoA carboxylase | Methylmalonyl CoA mutase

In the oxidation of odd chain FA, propionyl CoA carboxylase requires this coenzyme

Biotin

In the oxidation of odd chain FA, methylmalonyl CoA mutase requires what co enzyme

Vitamin B 12

Organelle which serves as a site for oxidation of very long FA ( C20, C22)

Peroxisomes

Oxidation of very long chain FA requires this additional enzyme

3,2 enoyl CoA isomerase

Lipogenesis/Beta-oxidation | Rate-limiting enzyme is acetyl CoA

Lipogenesis

Lipogenesis/Beta-oxidation | Rate-limiting enzyme is carnitine-palmitoyl tranferase

Beta-oxidation

Lipogenesis/Beta-oxidation | Subcellular location is cytosol

Lipogenesis

Lipogenesis/Beta-oxidation | Located in mitochondria

Beta-oxidation

Lipogenesis/Beta-oxidation | Transport mechanism is citrate shuttle

Lipogenesis

Lipogenesis/Beta-oxidation | Transport mechanism is carnitine shuttle

Beta-oxidation

Lipogenesis/Beta-oxidation | Repetitive steps is condensation-reduction-dehydration-reduction

Lipogenesis

Lipogenesis/Beta-oxidation | Repetitive steps is oxidation-hydration-oxidation-thiolysis

Beta-oxidation

Lipogenesis/Beta-oxidation | Product is palmitate

Lipogenesis

``` Lipogenesis/Beta-oxidation Products include Acetyl CoA NADH FADH2 ```

Beta-oxidation

Lipogenesis/Beta-oxidation | Activated by citrate

Lipogenesis

Lipogenesis/Beta-oxidation | Inhibited by long chain fatty acids

Lipogenesis

Lipogenesis/Beta-oxidation | Inhibited by malonyl CoA

Beta oxidation

Lipogenesis/Beta-oxidation | Favored by high insulin

Lipogenesis

Lipogenesis/Beta-oxidation | Favored by high glucagon

Beta oxidation

Rare disease that results in ichthyosis (scaly dermatitis), hair loss, poor wound healing, as well as visual and neurologic abnormalities

Deficiency of essential fatty acids

Hypoglycemia due to impaired fatty acid oxidation Lipid accumulation Muscle weakness

Canitine deficiency

Affects primarily the liver | Reduced fatty acid oxidation leading to severe hypoglycemia, coma, and death

Carnitine-Palmitoyl Transferase Deficiency

Affects primarily cardiac and skeletal muscle Cardiomyopathy Muscle weakness with myoglobinemia after prolonged exercise

Carnitine-Palmitoyl Transferase II deficiency

Dse that leads to decreased oxidation of fatty acids with 6-10 carbons

Medium Chain Fatty Acyl CoA Dehydrogenase | (MCAD) Deficiency

Most common inborn error of fatty acid oxidation Autosomal recessive M/c in Northern Europeans

Medium chain fatty acyl coa dehydrogenase deficiency

Severe hypoglycemia Accumulation of FA in urine Can manifest as Sudden Infant Death Syndrome

Medium Chain Fatty Acyl CoA Dehydrogenase Deficiency

Treatment for MCAD Deficiency

IV glucose in acute episodes | Avoidance of fasting

Dse caused by eating unripe fruit of the akee tree

Jamaican Vomiting Sickness

Dse characterized by toxin hypoglycin which inactivates medium- and short- chain acyl CoA dehydrogenase, inhibiting beta oxidatiom and causing hypoglycemia

Jamaican vomiting sickness

Dse characterized by deficiency of phytanoyl-CoA hydroxylase, leading to accumulation of phytanic acid

Refsum dse

In refsum dse, there is deficiency of ______ leading to accumulation of _______

Phytanoyl CoA hydroxylase | Phytanic acid

Peripheral neuropathy and ataxia, retinitis pigmentosa, abnormalities of skin and bone

Refsum dse

Tx for Refsum dse

Diet low in phytanic acid | Avoidance of dairy products, ruminant fat, and meat

Cerebrohepatorenal syndrome Inherited absence if peroxisomes in all tissues leading to marked accumulation of very long chain, saturated, unbranched fatty acids in liver, and CNS

Zelkweger syndrome

``` Liver dysfunction with jaundice Marked mental retardation Weakness Hypotonia Craniofacial dysmorphism (high forehead, shallow orbits, hypertelorism, high arched palate, abnormal helices or ears, retrognathia) Early death ```

Zellweger syndrome

Inability to transport VLCFAs across peroxisomal membrane leading to accumulation in the brain, adrenals, testes

Adrenoleukodystrophy (ALD)

Neurodegeneration (initial apathy and behavioral change, followed by visual loss, spasticity, ataxia) Adrenocortical insufficiency Hypogonadism

Adrenoleukodystrophy (ALD)

Tx for adrenoleukodystrophy

Adrenal hormone replacement therapy Hematopoietic stem cell transplantation Diet therapy to decrease endogenous synthesis of VLCFAs

Synthesis of ketone bodies that serve as alternative fuel for peripheral tissues

Ketogenesis

Subcellular site for ketogenesis

Mitchondria of liver cells

Substrate for ketogenesis

Acetyl CoA

3 products od ketogenesis

Acetoacetate Beta Hydroxybutyrate Acetone

Rate-limiting step for ketogenesis

Acetoacetyl CoA + Acetyl CoA —> HMG CoA | Enzyme: HMG CoA Synthase

Ketone bodies produced in ketogenesis get converted into ______ in extrahepatic tissues, which enters the TCA

Acetyl CoA

Pathway in which ketone bodies are oxidized primarily in the mitochondria of extrahepatic tissues

Ketolysis

Site of ketolysis

``` Mitochondria of extrahepatic tissues: Skeletal and heart muscle Kidney Intestines Brain ```

T/F | The liver uses ketone bodies as fuel

F | It lacks the enzyme succinyl CoA-acetoacetate-CoA transferase (thiophorase)

Enzyme lacking in liver, rendering it incapable of using ketone bodies as source of fuel

Thiophorase (succinyl CoA-acetoacetate CoA transferase)

In prolonged starvation and diabetic ketoacidosis, OAA is depleted for what pathway

Gluconeogenesis

In alcoholism, excess NADH shunts OAA to_______

Malate

Identify the dse: ``` Severe metabolic acidosis Dehydration Potassium depletion Fruity odor of breath Decreased sensorium, possibly coma ```

Diabetic ketoacidosis

T/F | In DKA dx, the sodium nitroprusside reaction measures acetone, acetoacetate, and hydroxybutyrate

F, NOT hydroxybutyrate

Cholesterol is stored as _________

Cholesteryl esters

Adults normally synthesize _ gram of cholesterol and consume about ___gram per day

1g | 0.3 g

Cholesterol structure has how many carbons

Cholesterol structure consists of a steroid nucleus composed of

Four hydrocarbon rings

In cholesterol structue, an eight-carbon brached hydrocarbon chain is attached to which carbon

Carbon 17 of D ring

In cholesterol structure, OH group is attached to _____

Carbon 3 of A ring

In cholesterol structure, double bond is located between which carbons

Carbon 5 and 6 of the B ring

Enzyme that converts cholesterol into bile acids

7a-hydroxylase

2 primary bile acids

Cholic acid | Chenodeoxycholic acid

2 secodary bile acids

Deoxycholic acid | Lithocholic acid

Bile salts are conjugated to _____ and ______

Taurine | Glycine

Enzyme that facilitates conversion of cholesterol to adrenal hormones and sex hormones

Desmolase Cholesterol -> pregnennolone

Substrate for cholesterol synthesis

Acetyl CoA

Subcellular site of cholesterol synthesis

Cytosol and endoplasmic reticulum

Tissue site if cholesterol synthesis

Virtually all tissues | Most important: liver, intestine, adrenal cortex, ovaries, testes, placenta

Rate-limiting step for cholesterol synthesis

``` Hydroxymethylglutaryl CoA (HMG CoA) —> mevalonate Enzyme: HMG CoA reductase ```

Rate-limiting enzyme for cholesterol synthesis

HMG CoA reductase

Co factor of HMG CoA reductase in cholesterol synthesis

NADPH

Sequence of cholesterol synthesis: | Acetyl CoA to _____

HMG CoA

Sequence of cholesterol synthesis: | HMG CoA to _______

Mevalonate

Sequence of cholesterol synthesis: | Mevalonate to _________, with loss of CO2

Isoprenyl pyrophosphates

Sequence of cholesterol synthesis: | Isoprenyl pyroohosphate to ________

Squalene

Sequence of cholesterol synthesis: | Squalene to ______

Lanosterol

Sequence of cholesterol synthesis: | Lanosterol to _______

Cholesterol

Competitive inhibitor of HMG CoA reductase

Statins

Regulation of cholesterol synthesis: | Cholesterol and metabolites repress transciptoom HMG CoA reductase via activation of _________ transcription factor

SREBP (Sterol Regulatory Element-Binding Protein)

HMG CoA reductase is activated by phosphorylation/dephosphorylation

Dephosphorylation

HMG CoA reductase is inactivated by phosphorylation/dephosphorylation

Phosphorylation

HMG CoA reductase is increased/decreased by | Insulin

Increased

HMG CoA reductase is increased/decreased by | T3 T4

Increased

HMG CoA reductase is increased/decreased by | Glucagon

Decreased

HMG CoA reductase is increased/decreased by | Glucocorticoids

Decreased

T/F | Cholesterol ring cannot be metabolized in humans

Intact sterol nucleus is eliminated through conversion to ____________ which are eliminated in feces

Bile acids and bile salts

Intact sterol nucleus is eliminated through secretion of cholesterol in bile, which is transported to the intestines, where bacteria may convert it to _______

Coprostanol or cholestanol

``` Dysmorphic facial features Microcephaly Mental retardation Congenital heart disease Stillbirth ``` Deficient 7-dehydrocholesterol reductase

Smith Lemli Opitz Syndrome

Enzyme deficiency in Smith Lemli Opitz Syndrome

7-dehydrocholesterol reductase

Results when more cholesterol enters the bile than can be solubilized by the bile salts and phosphatidyl choline present

Cholelithiasis

Congenital adrenal hyperplasia can result from deficiency in either 2 of these enzymes

21 a hydroxylase deficiency (most common) | 11B1 hydroxylase deficiency

What enzyme deficiency Minelarocorticoids and glucocorticoids are absent Overproduction of androgens leading to masculinization in females and early virilization in males

21 a hydroxylase deficiency (CAH)

What enzyme deficiency Decreased serum cortisol, aldosterone, corticosterone Increased deoxycoticosterone —> fluid retention (low renin hypertension) Overproduction of androgens —> masculinization and virilization

11 B1 Hydroxylase (CAH)

Identify dse | Autoimmune destruction of the adrenal cortex which leads to adrenocortical insufficiency

Addison Dse

``` Precipitateed by Infection Trauma Surgery Vomiting Diarrhea Noncompliance to replacement steroids ```

Addisonian crisis

Hyperpigmentation in Addison Dse is due to excess _____ stimulating melanocytes to produce melanin

ACTH

Spherical macromolecular complexes of lipids and proteins are called ____

Apolipoproteins

Core of plasma lipoprotein is composed of

Neutral lipids

Shell of plasma lipoprotein is made of _______

Amphiphatic apolipoproteins, phospholipid, and free fatty acids

Keeps lipids soluble in plama and provides an efficient transport mechanism for lipids to and from various tissues

Plasma lipoproteins

Organ source of chylomicrons

Intestine

Identify lipoprotein Largest diameter Lowest density Highest TAG content

Chylomicron

Protein and lipid % of chylomicron

1% | 99%

Identify lipoprotein 7-10% protein 90-93% lipid

VLDL

Source of VLDL

Liver (like HDL)

Identify lipoprotein | Highest cholesterol content

LDL

Identify lipoprotein | Highest protein content

HDL

Source of ILDL

VLDL

Source of LDL

VLDL

2 Organ sources of HDL

Liver | Intestine

Free fatty acids are transported in the plasma bound to ______, woth low levels during the well-fed state, but with subsequent rise in the fasted state

Albumin

Free fatty acids increase/decrease | Fasted state

Increase

Free fatty acids increase/decrease | Well-fed state

Decrease

Identify apoprotein | Cofactor of lecithin:cholesterol acyltransferase

Apo A 1

Identify apoprotein | Found mainly in HDL

Apo A 1

Identify apoprotein Main apoprotein Mediates secretion of VLDL Also found in VLDL, LDL

Apo B 100

Identify apoprotein | Mediates secretion of chylomicron

Apo B 48

Identify apoprotein | Cofactor of lipoprotein lipase

Apo C II

Identify apoprotein | Found in HDL, VLDL, chylomicrons

APO CII

Identify apoprotein | Mediates uptake of chylomicron remnants and IDLs

Apo E

Identify apoprotein | Found in chylomicron and ILDL

Apo E

Oxidized form of this lipoprotein cause endothelial damage which predisposes to atherosclerosis

LDL

Identify type of hyperlipoproteinemia | Familial lipoprotein lipase deficiency

Type I

Identify type of hyperlipoproteinemia | Deficiency of APO CII

Type I

``` Identify type of hyperlipoproteinemia High TAG low LDL Low HDL No increase risk of coronary disease ```

Type 1

T/F Type I hyperlipoproteinemia does not increase risk for coronary disease

Identify type of hyperlipoproteinemia | Defective LDL receptor

Type IIa

Identify type of hyperlipoproteinemia | Familiar hypercholesterolemia

Type IIa

Identify type of hyperlipoproteinemia High LDL and cholesterol Atherosclerosis and coronary disease

Type IIa

Identify type of hyperlipoproteinemia | Familial hyperlipoproteinemia

Type III

Identify type of hyperlipoproteinemia | Abnormal Apo E

Type III

Identify type of hyperlipoproteinemia Hypercholesterolemia Xanthomas Atherosclerosis

Type III

Identify type of hyperlipoproteinemia | Familial triacylglycerolemia

Type IV

Identify type of hyperlipoproteinemia | Overproduction of VLDL

Type IV

Identify type of hyperlipoproteinemia High VLDL and cholesterol Subnormal LDL and HDL Associated with CAD, DM Type 2, obesity, alcoholism

Type IV

``` Identify type of hyperlipoproteinemia Elevated lipoprotein (a), which is nearly identical to LDL ```

Familial lipoprotein (a) excess

Identify type of hyperlipoproteinemia Atherosclerosis Thrombosis due to inhibition of fibrinolysis

Familial lipoprotein (a) excess

Identify type of hyperlipoproteinemia | High HDL

Familial hyperalphalipoproteinemia

Identify type of hyperlipoproteinemia Rare Beneficial to health and longevity

Familial hyperalphalipoproteinemia (high HDL)

Identify type of hypolipoproteinemia Defect in the loading of Apo B with lipid No chylomicrons or VLDL

Abetalipoproteinemia

Identify type of hypolipoproteinemia Low TAG Accumulation of TAG in liver and intestines Treated with large volumes of fat-soluble vitamins, particularly vitamin E

Abetalipoproteinemia

Identify type of hypolipoproteinemia | Low or near absence of HDL

Familial alpha lipoprotein deficiency Tangier disease Fish eye disease Apo A1 deficinecies

Identify type of hypolipoproteinemia High TAG Absent HDL

Familial alpha lipoprotein deficiency Tangier disease Fish eye disease Apo A1 deficinecies

Chylomicron metabolism | ______ cells secrete nascent TAG-rich chylomicrons produced primarily from dietary (exogenous) lipids

Intestinal mucosal cells

Chylomicron metabolism | Apo ___ and Apo ___ are transferred from HDL to the nascent chylomicron

Apo CII and Apo E

Chylomicron metabolism | Extracellular _____, activated by APO CII, degrades TAG in chylomicron

Lipoprotein lipase

Chylomicron metabolism | Degradation of TAG by lipoprotein lipase yields _____ and _____

Free FA and Glycerol

Chylomicron metabolism | Apo ____ is returned to HDL

Apo CII

CE-rich chylomicron remnant bind through Apo ___ to specific receptors in the liver where they are endocytosed

APO E

VLDL metabolism | Liver secretes nascent, endogenously synthesized , TAG rich ______ particles

VLDL

VLDL metabolism | Apo C II and Apo E are transferred from ____ to nascent VLDL

HDL

VLDL metabolism | Extracellular lipoprotein lipase , activated by Apo ____, degrades TAG in VLDL

Apo CII

VLDL metabolism | Apo ___ and Apo ___ are returned to HDL

Apo C II and Apo E

VLDL metabolism | ____ binds to specific receptors on extrahepatic tissues and on the liver, where they are endocytosed

LDL

Lipids Flashcards

(220 cards)