Harper's Biochemistry Chapter 24 - Metabolism of Acylglycerols & Sphingolipids
93 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary catabolic process that triacylglycerols undergo?

  • Oxidation to form carbohydrates
  • Transamination to form amino acids
  • Deamination to remove ammonia
  • Hydrolysis to produce free fatty acids and glycerol (correct)

Which molecule directly serves as the substrate for the formation of both triacylglycerols and phosphoglycerols?

  • Glycerol-3-phosphate (correct)
  • Fatty acyl-CoA
  • Sphingosine
  • Dihydroxyacetone phosphate

Which compound acts as a precursor for the synthesis of all sphingolipids?

  • Glycosyltransferase
  • Phosphatidylcholine
  • Ceramide (correct)
  • Cholesterol

What leads to the generation of inositol phospholipids and cardiolipin from phosphatidate?

<p>Branch point in lipid metabolism (B)</p> Signup and view all the answers

Which statement accurately describes the formation of plasmalogens and platelet-activating factor (PAF)?

<p>They begin from dihydroxyacetone phosphate through a complex pathway. (B)</p> Signup and view all the answers

How are glycosphingolipids produced from ceramide?

<p>Via reaction with sugar residues (C)</p> Signup and view all the answers

What key role do various phospholipases play in lipid metabolism?

<p>Degradation and remodeling of phospholipids (B)</p> Signup and view all the answers

What diseases can result from defects in lipid metabolism pathways?

<p>Glycolipid storage diseases like Gaucher disease (D)</p> Signup and view all the answers

What is the primary function of the enzyme mentioned in the content?

<p>To catalyze the transfer of a fatty acid from lecithin to cholesterol (A)</p> Signup and view all the answers

Which of the following statements about GalCer is correct?

<p>GalCer is a prominent lipid in myelin sheaths (C)</p> Signup and view all the answers

Which fatty acid is involved in the biosynthesis of Ceramide as described?

<p>Palmitic acid (C)</p> Signup and view all the answers

How does UDPGal contribute to lipid metabolism?

<p>It provides galactose for the formation of galactosylceramide (C)</p> Signup and view all the answers

What role does the enzyme palmitoyltransferase play in lipid metabolism?

<p>It transfers palmitic acid to sphingosine to form ceramide (D)</p> Signup and view all the answers

What is the primary function of phospholipids in cell membranes?

<p>Serving as the main structural component (C)</p> Signup and view all the answers

Which enzyme is primarily responsible for the hydrolysis of triacylglycerols?

<p>Lipase (C)</p> Signup and view all the answers

In which tissue is lipolysis predominantly occurring?

<p>Adipose tissue (D)</p> Signup and view all the answers

What role do glycosphingolipids play in the cell membrane?

<p>Cell adhesion and recognition (B)</p> Signup and view all the answers

Which component of phospholipids might contribute to the pathology of respiratory distress syndrome in newborns?

<p>Dipalmitoyl lecithin (D)</p> Signup and view all the answers

What is the outcome of free fatty acid uptake into tissues after lipolysis?

<p>Conversion into ATP or reesterification (D)</p> Signup and view all the answers

What determines the utilization of glycerol in different tissues?

<p>Presence of glycerol kinase enzyme (B)</p> Signup and view all the answers

How do inositol phospholipids function within the cell membrane?

<p>As precursors of hormone second messengers (C)</p> Signup and view all the answers

Which type of lipid is primarily used for energy in various tissues?

<p>Free fatty acids (B)</p> Signup and view all the answers

What is the major component of cellular membranes involved in inflammation mediation?

<p>Platelet-activating factor (PAF) (C)</p> Signup and view all the answers

What is the primary role of glycerol kinase in lipid metabolism?

<p>Convert glycerol into glycerol-3-phosphate (C)</p> Signup and view all the answers

Which enzyme is responsible for the conversion of monoacylglycerol to diacylglycerol?

<p>Monoacylglycerol acyltransferase (B)</p> Signup and view all the answers

In the synthesis of phosphatidylinositol, what is the role of CDP-diacylglycerol?

<p>It acts as a substrate for diacylglycerol transferase (C)</p> Signup and view all the answers

Which pathway primarily produces triacylglycerol from glycerol-3-phosphate?

<p>Glycerol phosphate pathway (B)</p> Signup and view all the answers

What type of fat is primarily produced by diacylglycerol acyltransferase activity?

<p>Triacylglycerols (C)</p> Signup and view all the answers

Which of the following substrates directly contributes to the formation of phosphatidylserine?

<p>Phosphatidylethanolamine (C)</p> Signup and view all the answers

What is the relationship between glycolysis and lipid metabolism?

<p>Glycolysis produces direct precursors for lipid synthesis (C)</p> Signup and view all the answers

What is the role of phosphatidate phosphohydrolase in triacylglycerol metabolism?

<p>Converts phosphatidate to 1,2-diacylglycerol (B)</p> Signup and view all the answers

What characterizes the acyl-CoA that is mostly formed during lipid metabolism?

<p>It mainly consists of saturated fatty acids (A)</p> Signup and view all the answers

Which enzyme is involved in the hydrolysis of phosphatidate to generate diacylglycerol?

<p>Phosphatidate phosphohydrolase (D)</p> Signup and view all the answers

Which enzyme catalyzes the rate-limiting step in triacylglycerol synthesis?

<p>Diacylglycerol acyltransferase (A)</p> Signup and view all the answers

Which of the following statements is true regarding lipins?

<p>They have phosphatidate phosphohydrolase activity and regulate lipid metabolism. (C)</p> Signup and view all the answers

Which lipid is synthesized through the action of phosphocholine cytidyl transferase?

<p>Phosphatidylcholine (B)</p> Signup and view all the answers

What is the precursor for phosphoglycerols containing an ether link?

<p>Dihydroxyacetone phosphate (A)</p> Signup and view all the answers

What connection exists between carbohydrate and lipid metabolism in the context of pathway intermediates?

<p>Glycerol-3-phosphate and dihydroxyacetone phosphate are intermediates in both glycolysis and lipid metabolism. (D)</p> Signup and view all the answers

What is the initial product formed after the acylation of triose phosphates?

<p>Phosphatidate (D)</p> Signup and view all the answers

Which step of lipid biosynthesis does monoacylglycerol acyltransferase catalyze?

<p>Conversion of monoacylglycerol to 1,2-diacylglycerol (C)</p> Signup and view all the answers

Where is the majority of the activity of lipid metabolism enzymes localized?

<p>Endoplasmic reticulum primarily (B)</p> Signup and view all the answers

Which substance is NOT formed from glycerol-3-phosphate in lipid metabolism?

<p>Cholesterol (D)</p> Signup and view all the answers

What is the specific role of ATP in lipid biosynthesis?

<p>To activate fatty acids and glycerol before incorporation (A)</p> Signup and view all the answers

What metabolic process occurs to triacylglycerols before they can be utilized for energy?

<p>Hydrolysis to free fatty acids and glycerol (B)</p> Signup and view all the answers

Which of the following compounds is formed as a branch point in lipid synthesis leading to the formation of inositol phospholipids?

<p>Phosphatidate (B)</p> Signup and view all the answers

Which pathway produces plasmalogens and platelet-activating factor (PAF) from a common substrate?

<p>Dihydroxyacetone phosphate pathway (A)</p> Signup and view all the answers

What is the primary precursor for the synthesis of glycosphingolipids?

<p>Ceramide (D)</p> Signup and view all the answers

Which condition is directly associated with defects in sphingolipid metabolism?

<p>Gaucher disease (D)</p> Signup and view all the answers

What is the role of phospholipases in lipid metabolism?

<p>Degradation and remodeling of phospholipids (D)</p> Signup and view all the answers

Which lipid is primarily accumulated in conditions like Tay-Sachs disease due to metabolic defect?

<p>Glycosphingolipids (B)</p> Signup and view all the answers

What is primarily affected in multiple sclerosis regarding lipid composition?

<p>Loss of sphingolipids and myelin production (D)</p> Signup and view all the answers

Which lipid characteristic is associated with metachromatic leukodystrophy?

<p>Build-up of sulfatides in tissues (D)</p> Signup and view all the answers

Which effect does multiple sulfatase deficiency have on lipid metabolism?

<p>Accumulation of sulfogalactosylceramide and proteoglycans (C)</p> Signup and view all the answers

How is the lipid composition of white matter altered in demyelinating diseases?

<p>There is a notable loss of phospholipids and sphingolipids (C)</p> Signup and view all the answers

What is a significant symptom of multiple sulfatase deficiency?

<p>Abnormalities in neurological function (D)</p> Signup and view all the answers

Which protein family functions as both phosphatidate phosphohydrolase and transcription factor regulating lipid metabolism?

<p>Lipins (C)</p> Signup and view all the answers

What is the primary role of diacylglycerol acyltransferase in lipid biosynthesis?

<p>Converts 1,2-diacylglycerol to triacylglycerol (D)</p> Signup and view all the answers

Which substrate undergoes conversion to produce phosphoglycerols containing an ether link?

<p>Dihydroxyacetone phosphate (A)</p> Signup and view all the answers

Where is the active form of phosphatidate phosphohydrolase predominantly found?

<p>Membrane-bound structures (B)</p> Signup and view all the answers

What key branch point in lipid metabolism occurs after the conversion of phosphatidate?

<p>Conversion to 1,2-diacylglycerol (D)</p> Signup and view all the answers

Which of the following statements is true regarding the rate-limiting step in triacylglycerol synthesis?

<p>It is catalyzed by phosphatidate phosphohydrolase (B)</p> Signup and view all the answers

What major pathway does glycerol-3-phosphate primarily contribute to?

<p>Production of triacylglycerols (D)</p> Signup and view all the answers

Which enzyme is tasked specifically with converting monoacylglycerol to 1,2-diacylglycerol?

<p>Monoacylglycerol acyltransferase (C)</p> Signup and view all the answers

What triggers the activation of both glycerol and fatty acids in lipid biosynthesis?

<p>ATP phosphorylation (A)</p> Signup and view all the answers

What is the primary function of glycerol kinase in the biosynthesis of lipids?

<p>To activate glycerol to glycerol-3-phosphate (B)</p> Signup and view all the answers

Which compound serves as a precursor for the synthesis of phosphatidylinositol?

<p>CDP-diacylglycerol (D)</p> Signup and view all the answers

What is the result of the low activity of glycerol kinase in muscle or adipose tissue?

<p>Decreased synthesis of triacylglycerols (A)</p> Signup and view all the answers

What is the sequence of reactions necessary to synthesize phosphatidylcholine or phosphatidylethanolamine?

<p>Activation of choline followed by reaction with diacylglycerol (C)</p> Signup and view all the answers

Which molecule is crucial for the formation of phosphatidylserine from phosphatidylethanolamine?

<p>Serine (B)</p> Signup and view all the answers

What does CDP-ethanolamine react with to form phosphatidylethanolamine?

<p>1,2-diacylglycerol (C)</p> Signup and view all the answers

Which of the following statements correctly describes the role of phosphatidate in lipid biosynthesis?

<p>It is a precursor for all glycerophospholipids. (A)</p> Signup and view all the answers

Which enzyme catalyzes the formation of phosphatidylinositol from CDP-diacylglycerol?

<p>Phosphatidylinositol synthase (B)</p> Signup and view all the answers

In the context of triacylglycerol synthesis, which two reactions does acyl-CoA participate in?

<p>Combining with glycerol-3-phosphate and subsequent acylation (B)</p> Signup and view all the answers

What is the primary relationship between GalCer and GlcCer in lipid metabolism?

<p>GalCer is primarily found in extraneural tissues, while GlcCer is a major lipid of myelin. (D)</p> Signup and view all the answers

Which substrate is necessary for the formation of GalCer?

<p>Ceramide and uridine diphosphate galactose. (C)</p> Signup and view all the answers

What role does the enzyme mentioned in the content play in lipid metabolism?

<p>Transfers a fatty acid residue from lecithin to cholesterol. (D)</p> Signup and view all the answers

Which of the following best describes GlcCer?

<p>It is mainly found in extraneural tissues and is a complex glycosphingolipid. (D)</p> Signup and view all the answers

What is the main product formed as a result of the enzyme's activity described in the content?

<p>Cholesteryl esters and lysolecithin. (D)</p> Signup and view all the answers

Which metabolic pathway is primarily responsible for generating cholesteryl esters according to the information?

<p>Lecithin-cholesterol acyltransferase activity. (D)</p> Signup and view all the answers

What is the significance of the conversion of UDPGlc to UDPGal in lipid metabolism?

<p>It provides galactose for the formation of GalCer. (C)</p> Signup and view all the answers

Which molecule primarily functions as a substrate in the enzyme-catalyzed reaction forming GalCer?

<p>Uridine diphosphate galactose. (D)</p> Signup and view all the answers

What process converts ceramide into GalCer?

<p>Glycosylation with UDPGal. (B)</p> Signup and view all the answers

In what overall context is the enzyme that transfers a fatty acid from lecithin to cholesterol significant?

<p>It facilitates the formation of lipoproteins from cholesterol. (D)</p> Signup and view all the answers

Match the following lipid types with their primary characteristics:

<p>Phospholipids = Main component of cell membranes Triacylglycerols = Stored energy source Glycosphingolipids = Involved in cell recognition Inositol phospholipids = Precursor for hormone messengers</p> Signup and view all the answers

Match the following lipids with their associated functions:

<p>Dipalmitoyl lecithin = Lung surfactant component Platelet-activating factor = Mediates inflammation Free fatty acids = Energy substrate Glycerol = Intermediate for glycerol kinase utilization</p> Signup and view all the answers

Match the following enzymes with their roles in lipid metabolism:

<p>Lipase = Hydrolyzes triacylglycerols Glycerol kinase = Utilizes glycerol in tissues Phospholipase = Involved in phospholipid metabolism Acyltransferase = Catalyzes triacylglycerol formation</p> Signup and view all the answers

Match the following lipids with their location in the body:

<p>Glycosphingolipids = Outer leaflet of plasma membrane Triacylglycerols = Adipose tissue storage Inositol phospholipids = Cell membrane Dipalmitoyl lecithin = Lung tissue</p> Signup and view all the answers

Match the following lipid types with their metabolic pathways:

<p>Triacylglycerols = Undergo hydrolysis before energy use Glycosphingolipids = Involved in cell adhesion Inositol phospholipids = Serve as hormone precursors Phospholipids = Aid in membrane structure</p> Signup and view all the answers

Match the following lipid types with their primary function:

<p>Phosphatidylcholine = Major component of cell membranes Cardiolipin = Involved in mitochondrial function Phosphatidylethanolamine = Precursor for choline biosynthesis Platelet-activating factor (PAF) = Role in inflammation and immunity</p> Signup and view all the answers

Match the following phospholipids with their specific characteristics:

<p>Phosphatidylinositol = Involved in cell signaling Dihydroxyacetone phosphate = Intermediate in glycolysis Triacylglycerol = Primary storage form of fats Phosphatidate = Key precursor in lipid biosynthesis</p> Signup and view all the answers

Match the following metabolic processes with their relevant molecules:

<p>Synthesis of cardiolipin = From phosphatidylglycerol Formation of triacylglycerols = From free fatty acids Biosynthesis of plasmalogens = From ethanolamine Methylation process = In phosphatidylcholine synthesis</p> Signup and view all the answers

Match the following intermediates with their associated pathways:

<p>Glycerol-3-phosphate = Intermediate for phosphoglycerols 1,2-diacylglycerol phosphate = Involved in phosphatidylcholine formation 4,5-bisphosphate = Involved in signaling pathways Acyl-CoA = Involved in lipid biosynthesis</p> Signup and view all the answers

Match the following lipids with their respective roles in cellular metabolism:

<p>Plasmalogens = Found in cellular membranes Phosphatidylinositol = Source of inositol for signaling Triacylglycerol = Major energy storage molecule PAF = Mediates allergic reactions</p> Signup and view all the answers

Flashcards

Acylglycerols

A type of lipid that forms the majority of lipids in the body, including triacylglycerols.

Triacylglycerols

The major lipids in fat deposits and food; crucial for storage and transport.

Glycerol-3-phosphate

A substrate for both triacylglycerol and phosphoglycerol formation.

Phospholipids

Essential lipids with phosphate groups; crucial for cell membranes and other cellular functions.

Signup and view all the flashcards

Sphingolipids

A class of lipids with ceramide as the precursor.

Signup and view all the flashcards

Ceramide

The precursor for all sphingolipids; a crucial part of their structure.

Signup and view all the flashcards

Glycosphingolipids

Sphingolipids with sugar groups attached; involved in cell recognition.

Signup and view all the flashcards

Glycolipid storage diseases

Genetic disorders affecting glycolipid degradation; can cause severe health issues.

Signup and view all the flashcards

Catabolism of triacylglycerols

The breakdown of triacylglycerols into glycerol and fatty acids.

Signup and view all the flashcards

Phospholipases

Enzymes responsible for the degradation and remodeling of phospholipids.

Signup and view all the flashcards

Phospholipid Function in Membranes

Phospholipids and sphingolipids are crucial components of cell membranes due to their amphipathic nature.

Signup and view all the flashcards

Lipid Metabolism

Phospholipids participate in the metabolism of various other lipids, playing a role beyond membrane structure.

Signup and view all the flashcards

Specialized Phospholipid Functions

Specific phospholipids, like dipalmitoyl lecithin, have specialized roles, such as lung surfactant, which is crucial for respiration.

Signup and view all the flashcards

Inositol Phospholipids

Inositol phospholipids act as precursors of signaling molecules called hormone second messengers in cell membranes.

Signup and view all the flashcards

Platelet-Activating Factor (PAF)

PAF, an alkylphospholipid, mediates inflammation and plays a role in the inflammatory response.

Signup and view all the flashcards

Glycosphingolipid Function

Glycosphingolipids, with sphingosine, sugar, and fatty acid components, are found in the outer layer of the cell membrane and play a role in cell-cell interactions.

Signup and view all the flashcards

Triacylglycerol Hydrolysis

Triacylglycerols need to be broken down into their component fatty acids and glycerol by an enzyme called lipase before further metabolism.

Signup and view all the flashcards

Lipoprotein Metabolism

Free fatty acids released into the blood are transported by albumins and later taken up by tissues.

Signup and view all the flashcards

Fatty Acid Utilization

Fatty acids are oxidized in various tissues to produce energy or resynthesized into other lipids.

Signup and view all the flashcards

Glycerol Metabolism

Glycerol's fate depends on the presence of glycerol kinase in certain tissues, which determines how it is further metabolized.

Signup and view all the flashcards

Glycerol kinase

Enzyme converting glycerol to glycerol-3-phosphate

Signup and view all the flashcards

Glycerol-3-phosphate

Important intermediate in triacylglycerol and phospholipid synthesis

Signup and view all the flashcards

Dihydroxyacetone phosphate

Intermediate in glycolysis. In this case, a precursor in glycerol-3-phosphate synthesis

Signup and view all the flashcards

Monoacylglycerol

Acylglycerol with one fatty acid attached to glycerol

Signup and view all the flashcards

1,2-diacylglycerol

Acylglycerol with two fatty acid chains attached to glycerol

Signup and view all the flashcards

Triacylglycerol

Storage lipid with three fatty acid chains

Signup and view all the flashcards

Phosphatidate

Intermediate in phospholipid synthesis with glycerol and phosphate

Signup and view all the flashcards

Phosphatidylcholine

A phospholipid with choline head group

Signup and view all the flashcards

CDP-choline

Intermediate in phosphatidylcholine synthesis

Signup and view all the flashcards

Phosphatidylinositol

Phospholipid with inositol head group

Signup and view all the flashcards

Phosphatidylethanolamine

Phospholipid with ethanolamine head group

Signup and view all the flashcards

Phosphatidylserine

Phospholipid with serine head group

Signup and view all the flashcards

GalCer function

Major lipid in myelin.

Signup and view all the flashcards

GlcCer function

Major glycosphingolipid in extraneural tissues; precursor for complex glycosphingolipids.

Signup and view all the flashcards

Enzyme function in plasma

Transfers fatty acid from lecithin to cholesterol, forming cholesteryl ester and lysolecithin.

Signup and view all the flashcards

Cholesteryl ester source

Primarily formed by the enzyme. in plasma lipoproteins.

Signup and view all the flashcards

GalCer formation

From ceramide and UDPGal (formed from UDPGlc).

Signup and view all the flashcards

Triacylglycerol Biosynthesis

The process of creating triacylglycerols from smaller molecules, crucial for energy storage.

Signup and view all the flashcards

Phosphoglycerol Formation

The creation of phosphoglycerols, lipids containing glycerol and phosphate groups, from triose phosphates.

Signup and view all the flashcards

Phosphatidate Phosphohydrolase (PAP)

An enzyme that converts phosphatidate to 1,2-diacylglycerol in triacylglycerol synthesis.

Signup and view all the flashcards

Diacylglycerol Acyltransferase (DGAT)

The enzyme that converts 1,2-diacylglycerol to triacylglycerol.

Signup and view all the flashcards

Lipins

Proteins with phosphatidate phosphohydrolase activity, regulating lipid metabolism genes.

Signup and view all the flashcards

DGAT Role in Synthesis

DGAT is the enzyme specific to triacylglycerol synthesis and often rate-limiting.

Signup and view all the flashcards

Monoacylglycerol Pathway

A pathway that converts monoacylglycerol to diacylglycerol in intestinal mucosa.

Signup and view all the flashcards

Glycerol-3-Phosphate/Dihydroxyacetone Phosphate

Precursors for both triacylglycerols and phosphoglycerols; connect carbohydrate and lipid metabolism.

Signup and view all the flashcards

Triacylglycerol Catabolism

Breakdown of triacylglycerols into fatty acids and glycerol.

Signup and view all the flashcards

Glycerol-3-phosphate Role

A crucial intermediate in both triacylglycerol AND phospholipid synthesis.

Signup and view all the flashcards

Phospholipid Synthesis Branch Point

Phosphatidate is a key molecule where different phospholipid pathways diverge, leading to inositol phospholipids and others.

Signup and view all the flashcards

Sphingolipid Precursor

Ceramide is the foundational molecule for all sphingolipids.

Signup and view all the flashcards

Glycosphingolipid Formation

Glycosphingolipids are formed from ceramide by attaching sugar molecules.

Signup and view all the flashcards

Glycolipid Storage Diseases

Genetic disorders affecting glycolipid breakdown, often leading to severe illness.

Signup and view all the flashcards

Phospholipases Function

Enzymes that degrade and remodel phospholipids.

Signup and view all the flashcards

Acylglycerols

Lipids primarily consisting of glycerol and fatty acids.

Signup and view all the flashcards

Triacylglycerols

Major storage lipids in fat deposits and food important for energy storage.

Signup and view all the flashcards

Ethanolamine Activation

Ethanolamine is activated by phosphorylation with ATP, forming CDP-ethanolamine.

Signup and view all the flashcards

CDP-ethanolamine Function

CDP-ethanolamine combines with 1,2-diacylglycerol to produce phosphatidylethanolamine.

Signup and view all the flashcards

Phosphatidate

A crucial intermediate in the synthesis of triacylglycerols, phosphoglycerols, and cardiolipin.

Signup and view all the flashcards

Glycerol Kinase Role

Glycerol kinase activates glycerol to glycerol-3-phosphate.

Signup and view all the flashcards

Glycerol-3-phosphate Dehydrogenase

Enzyme converting dihydroxyacetone phosphate to glycerol-3-phosphate.

Signup and view all the flashcards

Phosphatidylserine Formation

Phosphatidylserine is produced from phosphatidylethanolamine by reacting with serine.

Signup and view all the flashcards

Triacylglycerol Biosynthesis

The process of creating triacylglycerols, a major energy storage lipid.

Signup and view all the flashcards

Phosphoglycerol Formation

Creation of phosphoglycerols, lipids containing glycerol and phosphate groups.

Signup and view all the flashcards

Phosphatidate Phosphohydrolase (PAP)

Enzyme converting phosphatidate to 1,2-diacylglycerol in triacylglycerol synthesis.

Signup and view all the flashcards

Diacylglycerol Acyltransferase (DGAT)

Enzyme converting 1,2-diacylglycerol to triacylglycerol.

Signup and view all the flashcards

Lipins

Proteins with phosphatidate phosphohydrolase activity, regulating lipid metabolism genes.

Signup and view all the flashcards

DGAT Role in Synthesis

DGAT is the enzyme specific to triacylglycerol synthesis and often the rate-limiting step.

Signup and view all the flashcards

Monoacylglycerol Pathway

Pathway converting monoacylglycerol to diacylglycerol in intestinal mucosa.

Signup and view all the flashcards

Glycerol-3-Phosphate/Dihydroxyacetone Phosphate

Precursors for triacylglycerols and phosphoglycerols; connecting carbohydrate and lipid metabolism.

Signup and view all the flashcards

Triacylglycerol

Storage lipid with three fatty acid chains attached to glycerol.

Signup and view all the flashcards

Phosphatidate

Intermediate in phospholipid synthesis with glycerol and phosphate.

Signup and view all the flashcards

GalCer function

Major lipid component of myelin.

Signup and view all the flashcards

GlcCer function

Major glycosphingolipid in extraneural tissues, precursor for complex glycosphingolipids.

Signup and view all the flashcards

Plasma enzyme function

Transfers fatty acids from lecithin to cholesterol, producing cholesteryl ester and lysolecithin.

Signup and view all the flashcards

Cholesteryl ester source

Primarily formed by an enzyme in plasma lipoproteins.

Signup and view all the flashcards

GalCer formation

From ceramide and UDPGal, which is formed from UDPGlc.

Signup and view all the flashcards

Lysosomal Disorders

Genetic conditions causing the buildup of lipids in cells, primarily affecting lysosomes.

Signup and view all the flashcards

Multiple Sulfatase Deficiency

A lysosomal disorder causing the buildup of certain sulfated lipids due to enzyme deficiencies.

Signup and view all the flashcards

Metachromatic Leukodystrophy

A lysosomal storage disorder characterized by sulfatides accumulation, damaging myelin.

Signup and view all the flashcards

Lipid Storage Diseases

Group of disorders marked by abnormal lipid accumulation in tissues, often nervous system.

Signup and view all the flashcards

Multiple Sclerosis

A demyelinating disease associated with loss of phospholipids and sphingolipids, impacting white matter.

Signup and view all the flashcards

Phospholipids and Sphingolipids

Essential lipids crucial for cell membranes and other cellular functions.

Signup and view all the flashcards

Surfactant Administration

Therapeutic use of natural or artificial surfactant for respiratory benefits in, e.g., premature infants.

Signup and view all the flashcards

Triacylglycerol Synthesis

Formation of Triacylglycerols through acylation of Glycerol-3-Phosphate.

Signup and view all the flashcards

Phosphatidate

Branch point in phospholipid and triacylglycerol synthesis pathways.

Signup and view all the flashcards

Cerebrospinal Fluid Phospholipid Levels

Elevated levels of phospholipids in cerebrospinal fluid indicate potential problems.

Signup and view all the flashcards

Amphipathic Nature of Phospholipids

Phospholipids have both hydrophilic (water-loving) and hydrophobic (water-fearing) regions, making them suitable components of cell membranes.

Signup and view all the flashcards

Triacylglycerol Hydrolysis

Breakdown of triacylglycerols into glycerol and fatty acids by an enzyme called lipase.

Signup and view all the flashcards

Lipolysis Location

Occurs mainly in adipose tissue, releasing free fatty acids into the bloodstream.

Signup and view all the flashcards

Fatty Acid Transport

Free fatty acids bind to serum albumin for transport in the blood.

Signup and view all the flashcards

Fatty Acid Uptake

Fatty acids are absorbed by various tissues for energy production or re-esterification.

Signup and view all the flashcards

Glycerol Metabolism

Glycerol's fate depends on the presence of glycerol kinase in certain tissues, leading to different metabolic pathways.

Signup and view all the flashcards

1,2-diacylglycerol phosphate

Intermediate in the phosphatidylcholine synthesis pathway.

Signup and view all the flashcards

Phosphatidylcholine synthesis

Process of creating phosphatidylcholine using ethanolamine.

Signup and view all the flashcards

Essential nutrient (choline)

Required for humans and many mammals for synthesizing phospholipids.

Signup and view all the flashcards

Triacylglycerol synthesis

Process of creating triacylglycerols using fatty acids.

Signup and view all the flashcards

Phosphatidylcholine

A phospholipid with a choline head group.

Signup and view all the flashcards

Cardiolipin

Mitochondrial phospholipid involved in function and structure.

Signup and view all the flashcards

Phosphatidylethanolamine

Phospholipid with an ethanolamine head group.

Signup and view all the flashcards

Fatty acid utilization

Fatty acids used for energy production or lipid synthesis.

Signup and view all the flashcards

Phosphatidate

Key intermediate in phospholipid and triacylglycerol synthesis.

Signup and view all the flashcards

Glycerol-3-phosphate

Important intermediate in triacylglycerol and phospholipid synthesis.

Signup and view all the flashcards

Dihydroxyacetone phosphate

Precursor in glycerol-3-phosphate synthesis.

Signup and view all the flashcards

Platelet-Activating Factor (PAF)

An alkylphospholipid that plays a role in inflammation.

Signup and view all the flashcards

Study Notes

Metabolism of Acylglycerols & Sphingolipids

  • Triacylglycerols are the major lipids in fat deposits and food, playing roles in transport, storage, and various diseases like obesity and diabetes
  • Sphingolipids are major components of cell membranes, essential for functions like cell adhesion, recognition, and in various signaling pathways. Examples include dipalmitoyl lecithin (lung surfactant) and platelet-activating factor (PAF)
  • Triacylglycerol catabolism begins with hydrolysis by lipase to fatty acids and glycerol
  • Glycerol is either phosphorylated (glycerol kinase) or metabolized through glycerol-3-phosphate dehydrogenase.
  • Fatty acids are transported to tissues for oxidation or re-esterification
  • Glycerol-3-phosphate is a precursor for both triacylglycerols and phosphoglycerols. A 'branch point' occurs at phosphatidate where pathways lead to inositol phospholipids, cardiolipin, and triacylglycerols.
  • Sphingolipids are derived from ceramide
  • Sphingomyelin and glycosphingolipids are formed from ceramide (with phosphatidylcholine and sugar molecules respectively).
  • Deficiencies in phospholipid or sphingolipid synthesis or breakdown can cause diseases.
  • Examples of diseases include Gaucher disease, Tay-Sachs disease, and Respiratory Distress Syndrome (IRDS).

Phosphoglycerol Synthesis

  • Synthesis of triacylglycerols and phosphoglycerols starts with triose phosphates and glycerol-3-phosphate.
  • Glycerol-3-phosphate is the common precursor in triacylglycerol, phosphoglycerol, and cardiolipin synthesis.
  • Diacylglycerols are produced via acylation reactions from glycerol-3-phosphate by glycerol-3-phosphate acyltransferase and 1-acylglycerol-3-phosphate acyltransferase.
  • Phosphatidate is a common intermediate, hydrolyzed to 1,2-diacylglycerol to be further acylated to triacylglycerol, or converted to other phospholipids.
  • Plasmalogens and platelet activating factor (PAF) are formed through pathways starting from dihydroxyacetone phosphate (a glycolysis intermediate).
  • Phospholipases play a critical role in the degradation and remodeling of phospholipids.
  • Phospholipids turnover rates vary (e.g., phosphate group versus acyl group)
  • Phospholipases allow for partial degradation and resynthesis of phospholipids

Glycerol Ether Phospholipids

  • Glycerol ether phospholipids, such as plasmalogens and PAF, are characterized by ether linkages rather than ester linkages
  • These lipids are largely contributed to by dihydroxyacetone phosphate
  • PAF is produced mainly in leukocytes and endothelial cells and has roles in mediating inflammation and contributing to allergic reactions.

Sphingolipids

  • Formed from ceramide (an N-acylsphingosine)
  • Sphingomyelins are formed from ceramide and phosphatidylcholine
  • Glycosphingolipids are composed of ceramide plus sugar residues; with simpler forms like cerebrosides (e.g., galactosylceramide, glucosylceramide) and more complex forms like gangliosides.
  • Biosynthesis occurs in endoplasmic reticulum, with glycosylation occurring usually in the Golgi and some in the plasma membrane.

Clinical Aspects

  • Lung surfactant deficiency: (dipalmitoyl-phosphatidylcholine) causes Respiratory Distress Syndrome (IRDS) in premature infants
  • Multiple sclerosis: involves loss of phospholipids and sphingolipids from white matter
  • Sphingolipidoses: a group of inherited diseases caused by defects in sphingolipid catabolism. Each leads to specific accumulation of particular lipids, causing a variety of pathologies and symptoms.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Quiz Team

Related Documents

Harper's Biochemistry Chapter 24 - Metabolism of Acylglycerols & Sphingolipids PDF

Description

This quiz explores the metabolism pathways of acylglycerols and sphingolipids, emphasizing their roles in cellular functions and disease. Topics include triacylglycerol catabolism, the significance of glycerol and fatty acids, and the biosynthesis of sphingolipids. Dive into the details of lipid metabolism and its implications in health.

More Like This

Use Quizgecko on...
Browser
Open
Browser
Browser