Lippincott's Biochemistry Chapter 17 - Phospholipid, Glycosphingolipid, and Eicosanoid Metabolism

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Questions and Answers

What characterizes the hydrophilic head of a phospholipid?

  • It contains a phosphate group and an attached alcohol. (correct)
  • It is nonpolar and hydrophobic in nature.
  • It is composed solely of fatty acids.
  • It has no significant role in membrane structure.

Which component is NOT typically associated with the hydrophobic tail of phospholipids?

  • Glycerol backbone
  • Alcohols like choline (correct)
  • Fatty acid chains
  • Sphingosine

What defines the term 'amphipathic' as it relates to phospholipids?

  • They have both polar and nonpolar regions. (correct)
  • They are solely hydrophobic in nature.
  • They are neutral molecules.
  • They are exclusively found in membranes.

Which type of lipid is primarily found in cell membranes?

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

Which alcohol is commonly attached to the hydrophilic part of phospholipids?

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

What role do the nonpolar portions of membrane constituents play?

<p>They associate with the hydrophobic portions of phospholipids. (C)</p> Signup and view all the answers

Which of the following structures would NOT be classified as a phospholipid?

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

What is the main function of phospholipids in biological membranes?

<p>To form a barrier and compartmentalize cell functions. (D)</p> Signup and view all the answers

What is the primary role of cytidine diphosphate (CDP) in glycerophospholipid synthesis?

<p>To link diacylglycerol (DAG) with phosphomonoesters. (D)</p> Signup and view all the answers

Which characteristic is commonly observed in the fatty acids esterified at carbon 1 and carbon 2 of glycerophospholipids?

<p>Carbon 1 usually contains saturated fatty acids while carbon 2 has unsaturated ones. (B)</p> Signup and view all the answers

In which cellular organelle is most phospholipid synthesis primarily located?

<p>Smooth endoplasmic reticulum (SER) (D)</p> Signup and view all the answers

What type of compounds are formed when an alcohol is activated through the action of CDP-alcohol?

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

Which of the following statements regarding lipid composition in membranes is true?

<p>Sphingolipids include components that differentiate them from glycerophospholipids. (A)</p> Signup and view all the answers

What is the defining structural component of glycerophospholipids?

<p>A glycerol backbone with two fatty acids and a phosphate group (D)</p> Signup and view all the answers

Which of the following is NOT a product formed from phosphatidic acid (PA)?

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

What is the primary role of cardiolipin in eukaryotic cells?

<p>To maintain the structure and function of mitochondrial membranes (D)</p> Signup and view all the answers

Which of the following is true regarding the phosphate group of phosphatidic acid?

<p>It contributes to the overall polarity of the molecule. (D)</p> Signup and view all the answers

Which of the following accurately describes the relationship between glycerophospholipids and sphingolipids?

<p>They both contain fatty acids but differ in their backbone structure. (C)</p> Signup and view all the answers

In which cellular component is cardiolipin most prominently found?

<p>Inner mitochondrial membrane (D)</p> Signup and view all the answers

What reaction occurs when phosphatidic acid is combined with serine?

<p>Formation of phosphatidylserine (PS) (C)</p> Signup and view all the answers

Which fatty acid structure is commonly associated with glycerophospholipids?

<p>One saturated and one unsaturated fatty acid (A)</p> Signup and view all the answers

Which of the following statements about phosphatidic acid is true?

<p>It acts as a precursor for various glycerophospholipids. (B)</p> Signup and view all the answers

What type of bond forms between the alcohol group and the phosphate group in glycerophospholipids?

<p>Ester bond (A)</p> Signup and view all the answers

What are glycerophospholipids primarily characterized by?

<p>The inclusion of glycerol in their structure (A)</p> Signup and view all the answers

Which class of phospholipids contains sphingosine as a backbone?

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

How do membrane phospholipids contribute to cellular functions?

<p>By providing anchoring sites for some proteins (A)</p> Signup and view all the answers

What is one of the key roles of nonmembrane phospholipids in the body?

<p>Serving as components of lung surfactant (A)</p> Signup and view all the answers

What distinguishes plasmalogens from regular glycerophospholipids?

<p>They have an unsaturated alkyl group attached by an ether linkage. (B)</p> Signup and view all the answers

Which process do phospholipids aid in due to their detergent properties?

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

In terms of membrane lipid composition, composed primarily of glycerol, what are phosphoglycerides?

<p>A class of glycerophospholipids (C)</p> Signup and view all the answers

Which phospholipid is known to be abundant in nerve tissue?

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

What does the hydrophilic head of phospholipids interact with?

<p>Aqueous environments inside and outside cells (C)</p> Signup and view all the answers

What is the role of platelet-activating factor (PAF) in the body?

<p>It acts as a thrombotic agent and triggers acute inflammatory responses. (C)</p> Signup and view all the answers

Which of the following statements is false regarding phospholipids?

<p>All phospholipids contain sphingosine. (B)</p> Signup and view all the answers

Which of the following statements about cardiolipin is correct?

<p>It plays a role in mitochondrial energy production. (D)</p> Signup and view all the answers

Which function is NOT associated with membrane phospholipids?

<p>Serving solely as energy reserves (C)</p> Signup and view all the answers

What type of linkage does the alkyl group in platelet-activating factor have?

<p>A saturated ether linkage. (D)</p> Signup and view all the answers

What is a defining feature of lipid signaling molecules?

<p>They can be generated from membrane phospholipids. (A)</p> Signup and view all the answers

What characterizes the structural nomenclature of plasmalogens?

<p>They are named with 'al' instead of 'yl'. (A)</p> Signup and view all the answers

What is true about the fatty acid composition of ether lipids?

<p>They can contain both saturated and unsaturated fatty acids. (D)</p> Signup and view all the answers

Which of the following phospholipids is significant in heart muscle?

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

Which statement describes sphingolipid metabolism?

<p>Sphingolipids are derived from palmitoyl-CoA and serine. (A)</p> Signup and view all the answers

What type of compound do phospholipids primarily represent in cell membranes?

<p>Amphipathic molecules (A)</p> Signup and view all the answers

Which type of bond connects the alcohol to the phosphate group in phospholipids?

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

What characteristic is shared by both phospholipids and fatty acids?

<p>Amphipathic nature (A)</p> Signup and view all the answers

Which of the following alcohols can be attached to the hydrophilic head of phospholipids?

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

What part of the phospholipid molecule interacts with nonpolar membranes?

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

Which feature distinguishes phospholipids from simple triglycerides?

<p>Incorporation of phosphate groups (B)</p> Signup and view all the answers

What is the nature of the interactions formed between the hydrophobic portions of phospholipids?

<p>Van der Waals forces (B)</p> Signup and view all the answers

What is a primary biological effect of platelet-activating factor (PAF)?

<p>Promotes aggregation of platelets and activates inflammatory cells (D)</p> Signup and view all the answers

Which structural component defines sphingomyelin as a significant sphingophospholipid in humans?

<p>Amino alcohol backbone of sphingosine with phosphorylcholine (B)</p> Signup and view all the answers

What potential impact does PAF have on blood pressure?

<p>It lowers blood pressure (B)</p> Signup and view all the answers

Which of the following statements about the structure of sphingomyelin is correct?

<p>Phosphorylcholine is esterified to the alcohol group at carbon 1 of sphingosine. (C)</p> Signup and view all the answers

What role does ceramide play in sphingolipid metabolism?

<p>It acts as a precursor for the formation of glycolipids. (D)</p> Signup and view all the answers

What type of phospholipids contain sphingosine in their structure?

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

What is the primary function of phosphatidylethanolamine in cell membranes?

<p>Anchor proteins to membranes (C)</p> Signup and view all the answers

What distinguishes nonmembrane phospholipids from membrane phospholipids?

<p>Their location in the body (B)</p> Signup and view all the answers

What role do membrane phospholipids play in biological membranes?

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

Which class of phospholipids is characterized by having glycerol as the backbone?

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

What unique property of phospholipids aids in cholesterol solubilization?

<p>Their amphipathic nature (C)</p> Signup and view all the answers

Which phospholipid is primarily regarded as a reservoir for intracellular messengers?

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

Which of the following functions is essential for the role of lung surfactant?

<p>Reduction of surface tension (C)</p> Signup and view all the answers

Which condition must be fulfilled for a phospholipid to function as a detergent for solubilizing cholesterol?

<p>Amphipathic structure (A)</p> Signup and view all the answers

What type of linkage connects the unsaturated alkyl group in plasmalogens to the glycerol molecule?

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

Which substance is primarily responsible for detecting antibodies in the Wasserman test?

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

What is the primary fatty acid structure present at carbon 2 of platelet-activating factor (PAF)?

<p>No fatty acid, only an acetyl group (D)</p> Signup and view all the answers

Which of the following claims about phosphatidalethanolamine is accurate?

<p>It is a significant plasmalogen found in nerve tissue. (B)</p> Signup and view all the answers

Which component is a key feature of platelet-activating factor (PAF)?

<p>Saturated alkyl group at carbon 1 (B)</p> Signup and view all the answers

What differentiates plasmalogens from other ether lipids in terms of structural nomenclature?

<p>Presence of 'al' in their names (B)</p> Signup and view all the answers

Which phospholipid is primarily shown to enhance inflammatory responses?

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

In which type of tissue is phosphatidalcholine predominantly found?

<p>Heart muscle (A)</p> Signup and view all the answers

What type of group is found in the specific structure of cardiolipin?

<p>Four fatty acid chains attached to two glycerol molecules (A)</p> Signup and view all the answers

What role do plasmalogens play in biological membranes compared to other lipids?

<p>They facilitate signaling processes. (C)</p> Signup and view all the answers

What is the simplest glycerophospholipid derived from phosphatidic acid?

<p>Phosphatidic acid (A)</p> Signup and view all the answers

Which of the following compounds results from the esterification of phosphatidic acid (PA) with ethanolamine?

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

Which feature distinguishes cardiolipin from other glycerophospholipids?

<p>It consists of two molecules of phosphatidic acid. (C)</p> Signup and view all the answers

In which part of eukaryotic cells is cardiolipin predominantly located?

<p>Inner mitochondrial membrane (A)</p> Signup and view all the answers

What molecule is formed when phosphatidic acid is reacted with choline?

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

Which of the following lipid classes is considered a precursor for glycerophospholipids?

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

What is the structural basis for the unique properties of glycerophospholipids?

<p>Two fatty acid chains and a phosphate group (B)</p> Signup and view all the answers

How does cardiolipin influence mitochondrial function?

<p>It aids in the assembly of respiratory chain complexes. (A)</p> Signup and view all the answers

Which of the following entities is NOT primarily comprised of glycerophospholipids?

<p>Triglyceride storage (A)</p> Signup and view all the answers

What functional group is characteristic of phosphatidic acid?

<p>Phosphate group (A)</p> Signup and view all the answers

Match the following components of phospholipids with their descriptions:

<p>Hydrophilic head = Contains a phosphate group and an alcohol Hydrophobic tail = Made up of fatty acids or hydrocarbons Glycerol backbone = Component connecting to fatty acids Phosphodiester bond = Linkage between alcohol and phosphate group</p> Signup and view all the answers

Match the following types of lipids with their primary structure:

<p>Phospholipids = Composed of glycerol, fatty acids, and a phosphate group Glycosphingolipids = Contain sphingosine and sugar groups Eicosanoids = Derived from arachidonic acid Triglycerides = Made up of glycerol and three fatty acids</p> Signup and view all the answers

Match the following types of phospholipids with their corresponding backbone components:

<p>Glycerophospholipids = Glycerol Sphingolipids = Sphingosine Phosphatidylethanolamine = Glycerol Cardiolipin = Sphingosine</p> Signup and view all the answers

Match the following terms related to phospholipid properties:

<p>Amphipathic = Having both hydrophilic and hydrophobic regions Nonpolar = Characteristic of hydrophobic tails Polar = Describes the behavior of the hydrophilic head DAG = Diacylglycerol, a component of phospholipids</p> Signup and view all the answers

Match the following types of alcohol with their association in phospholipids:

<p>Serine = Commonly attached to hydrophilic head Ethanolamine = An alcohol linked to phospholipids Choline = Another alcohol option for the polar head Glycerol = Not typically part of the hydrophilic head</p> Signup and view all the answers

Match the following phospholipid functions with their descriptions:

<p>Lung surfactant = Reduces surface tension in alveoli Bile components = Aids in cholesterol solubilization Cell membrane anchoring = Stabilizes membrane proteins Intracellular messengers = Transmits signaling pathways</p> Signup and view all the answers

Match the following nonmembrane phospholipids with their primary roles:

<p>Phosphatidylcholine = Structural component of membranes Phosphatidic acid = Biosynthesis precursor Cardiolipin = Energy production in mitochondria Platelet-activating factor = Regulates inflammation</p> Signup and view all the answers

Match the following cellular functions with their relevant phospholipid types:

<p>Cardiolipin = Found primarily in heart tissue Platelet-activating factor (PAF) = Involved in inflammatory responses Phosphatidic acid = Intermediate in phospholipid biosynthesis Phosphatidylcholine = Key component in cell membranes</p> Signup and view all the answers

Match the following hydrophilic interactions with their corresponding environments:

<p>Intracellular = Inside the cell Extracellular = Outside the cell Aqueous environment = Water-based solutions Membrane interface = Boundary of lipid bilayer</p> Signup and view all the answers

Match the following phospholipids with their specific roles:

<p>Phosphatidylethanolamine = Cell membrane structure Phosphatidylcholine = Fat metabolism Phosphatidic acid = Lipid signaling Cardiolipin = Mitochondrial function</p> Signup and view all the answers

Flashcards

Phospholipid

A polar, ionic compound with a hydrophilic head and a hydrophobic tail. It's a major component of cell membranes.

Hydrophilic head

The water-loving part of a phospholipid, containing the phosphate group and attached alcohol.

Hydrophobic tail

The water-fearing part of a phospholipid, composed of fatty acids or FA-derived hydrocarbons.

Amphipathic

A molecule having both a hydrophilic and a hydrophobic part.

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Phosphodiester bond

The bond that connects the alcohol to the diacylglycerol or sphingosine in a phospholipid.

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Cell membrane

A structure primarily composed of phospholipid molecules.

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Glycerophospholipids

A major class of phospholipids, crucial components of cell membranes, derived from phosphatidic acid.

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Phosphatidic acid (PA)

The simplest phosphoglyceride; a precursor to other phospholipids. It has a glycerol backbone with fatty acids on two carbons and a phosphate group on carbon 3.

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Phospholipid synthesis

The creation of new phospholipids, usually by adding an alcohol to the phosphate group of phosphatidic acid.

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Phosphatidylcholine (PC)

A common phospholipid, also known as lecithin, that results from adding choline to phosphatidic acid.

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Cardiolipin

A unique phospholipid, found primarily in the mitochondrial inner membrane; formed by two phosphatidic acid molecules linked to glycerol.

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Mitochondrial Inner Membrane

The membrane within mitochondria where cardiolipin is predominantly found; crucial for the electron transport chain.

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Glycerophospholipid structure

A type of phospholipid containing glycerol as its backbone.

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Phospholipid function

Phospholipids form cell membranes, act as messengers, and anchor proteins.

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Hydrophilic head

The polar part of a phospholipid that interacts with water.

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Phospholipid location

Phospholipids are found in cell membranes, both internal and external.

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Nonmembrane phospholipids

Phospholipids not part of membranes, but have other bodily roles.

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Phospholipid function in body

Some non-membrane phospholipids such as lung surfactants aid cholesterol in bile.

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Cardiolipin

Antigenic phospholipid recognized by antibodies against Treponema pallidum (syphilis bacterium).

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Plasmalogens

Ether phosphoglycerides, where carbon 1 fatty acid is replaced by an unsaturated alkyl group linked by an ether, not ester.

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Platelet-activating factor (PAF)

Ether glycerophospholipid with a saturated alkyl ether link at carbon 1 and an acetyl residue at carbon 2 (instead of a fatty acid).

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Glycerophospholipid synthesis

Formation of glycerophospholipids, important cell membrane components, through activation and attachment of either diacylglycerol (DAG) or alcohol to cytidine diphosphate (CDP).

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CDP Activation

Process of attaching cytidine diphosphate (CDP) to diacylglycerol (DAG) or an alcohol to activate them for phospholipid synthesis.

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Phospholipids synthesis location

Primarily occurs in the smooth endoplasmic reticulum (SER).

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Fatty Acid variation in phospholipids

Fatty acids attached to phospholipids' glycerol backbone can vary, leading to diverse phospholipid types.

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Activated intermediate

A molecule carrying a chemical group ready to be added to another molecule, e.g., CDP-bound structures.

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Phospholipids: Structure

Polar molecules with a hydrophilic head (phosphate group plus attached alcohol) and a hydrophobic tail (fatty acids).

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Phospholipid Function

Major components of cell membranes, positioning hydrophobic tails inside and hydrophilic heads outside.

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Amphipathic

Describing molecules with both hydrophilic and hydrophobic parts.

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Phosphodiester Bond

The bond connecting the alcohol in a phospholipid to a glycerol backbone.

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Cell Membrane Composition

Primarily composed of phospholipids, alongside proteins, cholesterol, and glycolipids.

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Hydrophilic Head

The water-loving part of a phospholipid, containing phosphate and attached alcohol.

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Hydrophobic Tail

The water-fearing part of a phospholipid, made of fatty acids or FA-derived hydrocarbons.

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Hydrophilic head

The polar part of a phospholipid that attracts water.

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Phospholipid structure

Consists of a hydrophilic head (attracts water) and hydrophobic tails (repel water).

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Glycerophospholipid

A type of phospholipid with a glycerol backbone.

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Phospholipid function

Form cell membranes, act as messengers, and anchor proteins.

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Non-membrane phospholipids

Phospholipids not part of cell membranes, but serve other bodily functions.

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Phospholipid location

Found in cell membranes, both internal and external.

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Cardiolipin

A phospholipid recognized by antibodies against Treponema pallidum (the syphilis bacterium); it's antigenic.

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Plasmalogens

Ether phosphoglycerides where carbon 1 has an unsaturated alkyl group linked by an ether, not an ester.

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Platelet-activating factor (PAF)

An ether glycerophospholipid with a saturated alkyl ether link at carbon 1 and an acetyl group at carbon 2.

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Glycerophospholipids

Major class of phospholipids found in cell membranes; derived from phosphatidic acid.

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Phosphatidic Acid (PA)

Simplest phosphoglyceride, precursor to other phospholipids; glycerol backbone with fatty acids on carbons 1 and 2, and phosphate on carbon 3.

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Phosphatidylserine (PS)

Phospholipid formed by adding serine to phosphatidic acid.

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Phosphatidylethanolamine (PE)

Phospholipid formed by adding ethanolamine to phosphatidic acid.

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Phosphatidylcholine (PC)

Phospholipid formed by adding choline to phosphatidic acid; also known as lecithin.

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Phosphatidylinositol (PI)

Phospholipid formed by adding inositol to phosphatidic acid.

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Phosphatidylglycerol (PG)

Phospholipid formed by adding glycerol to phosphatidic acid.

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Cardiolipin

Phospholipid formed from two phosphatidic acid molecules linked to glycerol; mainly found in mitochondrial inner membranes.

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Mitochondrial inner membrane

Membrane within mitochondria, primary location for cardiolipin.

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Platelet-activating factor (PAF)

An ether glycerophospholipid that activates platelets and inflammatory cells, causing hypersensitivity and other reactions.

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Sphingomyelin

A major sphingophospholipid in humans, crucial component of myelin sheath.

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PAF function

PAF activates inflammatory responses, causes platelet aggregation, and lowers blood pressure

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Sphingosine

An amino alcohol, the backbone of sphingomyelin, a major type of phospholipid

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Ceramide

A molecule built from sphingosine and a fatty acid, that can be a precursor to glycolipids, it's part of the sphingomyelin pathway

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Hydrophilic head of phospholipid

The polar part of a phospholipid that interacts with water; it typically contains a phosphate group and an attached alcohol.

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Phospholipid function in membranes

Form cell membranes; act as messengers, and anchor proteins.

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Non-membrane phospholipids

Phospholipids not found in cell membranes, but fulfilling other bodily functions, like lung surfactant and bile.

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Glycerophospholipid

A type of phospholipid that contains glycerol as its backbone.

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Phosphatidic acid (PA)

The simplest type of phosphoglyceride, acting as a precursor for other phospholipids.

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Phosphatidylcholine (PC)

A common phospholipid formed by adding choline to phosphatidic acid. Also known as lecithin.

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Phospholipid

A polar, ionic compound with a hydrophilic head and a hydrophobic tail; a major cell membrane component.

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Hydrophilic head

The water-attracting part of a phospholipid, consisting of the phosphate group and an attached alcohol.

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Hydrophobic tail

The water-repelling part of a phospholipid, composed of fatty acids or derived hydrocarbons.

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Amphipathic

Describing a molecule with both hydrophilic and hydrophobic regions.

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Phosphodiester bond

The bond connecting the alcohol to the glycerol backbone or sphingosine in a phospholipid.

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Cell membrane

A structure primarily composed of phospholipids, proteins, and cholesterol.

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Glycerophospholipid

A major class of phospholipids that have a glycerol backbone.

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Phosphatidic Acid (PA)

The simplest type of phosphoglyceride; a precursor for other phospholipids.

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Phospholipid function

Form cell membranes, act as messengers, and anchor proteins.

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Phospholipid location

Found in cell membranes, both internal and external.

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Non-membrane phospholipids

Serve various functions in the body, but not primarily part of cell membranes.

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Study Notes

Phospholipid, Glycosphingolipid, and Eicosanoid Metabolism

  • Phospholipids are polar, ionic compounds composed of an alcohol attached to either diacylglycerol or sphingosine via a phosphodiester bond.
  • They are amphipathic, with a hydrophilic head (phosphate group and attached alcohol) and a hydrophobic tail (fatty acids or FA-derived hydrocarbons).
  • Glycerophospholipids are the major class of phospholipids, containing glycerol as their backbone.
  • They are the predominant lipids in cell membranes.
  • Phosphatidic acid (PA) is the simplest phosphoglyceride, a precursor to other glycerophospholipids.
  • Glycerophospholipids include phosphatidylserine, phosphatidylethanolamine, and phosphatidylcholine (lecithin).
  • Cardiolipin is a unique glycerophospholipid composed of two PA molecules esterified to glycerol.
  • Plasmalogens are ether phosphoglycerides, with an alkyl group attached to glycerol by an ether linkage instead of an ester linkage.
  • Platelet-activating factor (PAF) is an ether glycerophospholipid with a saturated alkyl group at carbon 1 and an acetyl group at carbon 2.
  • Sphingophospholipids, like sphingomyelin, have sphingosine as their backbone.
  • Sphingomyelin is the most significant sphingophospholipid in humans.
  • Phospholipid synthesis typically involves the donation of phosphatidic acid (PA) from CDP-DAG to an alcohol or the donation of the phosphomonoester of the alcohol from CDP-alcohol to DAG.
  • Phosphatidylcholine (PC) and phosphatidylethanolamine (PE) are the most abundant phospholipids in most eukaryotic cells.
  • PC and PE are synthesized from preexisting choline and ethanolamine.
  • Phosphatidylinositol (PI) is an unusual phospholipid that contains stearic acid at carbon 1 and arachidonic acid at carbon 2 and serves as a reservoir for arachidonic acid.
  • Phosphatidylinositol is involved In signal transduction by phosphorylation, which produces polyphosphoinositides like phosphatidylinositol 4,5-bisphosphate (PIP2).
  • Phosphatidylglycerol and cardiolipin are also membrane components.
  • Sphingomyelin is degraded by sphingomyelinase into ceramide and phosphorylcholine.
  • Various phospholipases hydrolyze phosphodiester bonds of phosphoglycerides.
  • Phospholipase A2 removes fatty acids from carbon 1 or 2.
  • Phospholipase D releases the alcohol head group.
  • Phospholipase C cleaves PIP2 into inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG), which are involved in signaling cascades.

Eicosanoids

  • The eicosanoids include prostaglandins (PGs), thromboxanes (TXs), and leukotrienes (LTs).
  • They are derived from polyunsaturated fatty acids with 20 carbons.
  • Prostaglandins and thromboxanes are synthesized from arachidonic acid via cyclooxygenase enzymes (COX-1 and COX-2).
  • Leukotrienes are synthesized from arachidonic acid via 5-lipoxygenase.
  • Prostaglandins and thromboxanes are involved in inflammation, pain, fever, and blood clotting.
  • Leukotrienes are primarily involved in allergic and inflammatory responses.
  • Aspirin inhibits prostaglandin and thromboxane synthesis by inhibiting cyclooxygenase.

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