🎧 New: AI-Generated Podcasts Turn your study notes into engaging audio conversations. Learn more

Cell Membrane and Cytoskeleton: Post learning - cholesterol and phospholipids
40 Questions
1 Views

Cell Membrane and Cytoskeleton: Post learning - cholesterol and phospholipids

Created by
@DivineRed

Podcast Beta

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Which two main classes can lipids be broken down into structurally?

  • Fatty acids and isoprenoids (correct)
  • Phospholipids and fatty acids
  • Phospholipids and sphingolipids
  • Sphingolipids and isoprenoids
  • What are the three components of a phospholipid?

  • Hydrocarbon chain, backbone phosphatidic acid, and phosphate-alcohol head group
  • Hydrocarbon chain, backbone sphingomyelin, and phosphate-alcohol head group
  • Hydrocarbon chain, backbone glycerol, and phosphate-alcohol head group (correct)
  • Hydrocarbon chain, backbone ceramide, and phosphate-alcohol head group
  • Which phospholipid has both fatty acids linked to the glycerol backbone with an ester link?

  • Phosphatidate (correct)
  • Phosphatidylcholine
  • Phosphatidylethanolamine
  • Phosphatidylserine
  • Which phospholipid has one fatty acid linked to the glycerol backbone with an ether link while the other has an ester link?

    <p>Phosphatidylcholine</p> Signup and view all the answers

    Which phosphoglyceride is the most common in the cell membrane?

    <p>Phosphatidylcholine</p> Signup and view all the answers

    Which phospholipid contains a ceramide backbone?

    <p>Sphingomyelin</p> Signup and view all the answers

    Which class of lipids can sphingomyelin also be classified as?

    <p>Sphingolipids</p> Signup and view all the answers

    What is the role of the transfer molecule CDP in phospholipid synthesis?

    <p>It transfers the phosphate-alcohol head group to the glycerol backbone</p> Signup and view all the answers

    How do phospholipids synthesized in the smooth ER reach the plasma membrane?

    <p>Through active transport</p> Signup and view all the answers

    What is the basic structure of a phospholipid?

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

    What is the composition of a phospholipid?

    <p>2 Hydrocarbon chains, glycerol, phosphate-alcohol head group</p> Signup and view all the answers

    Where does phospholipid synthesis primarily occur?

    <p>On the luminal surface of the smooth ER and the inner mitochondrial membrane</p> Signup and view all the answers

    Which steps are involved in the synthesis of glycerophospholipids?

    <p>Synthesis of glycerol shared with backbone and attachment of fatty acids to backbone via ester linkage</p> Signup and view all the answers

    How is the head group added to phosphatidic acid?

    <p>One of the hydroxyl is first activated by attachment of a nucleotide, cytosine diphosphate (CDP)</p> Signup and view all the answers

    What can phosphatidylserine be converted to in a reversible headgroup exchange reaction?

    <p>Phosphatidylethanolamine</p> Signup and view all the answers

    What is the role of phosphatidylinositol in the cell membrane?

    <p>It plays an important role in cell signalling</p> Signup and view all the answers

    How do newly made phospholipids reach the other side of the smooth ER membrane and the cell membrane?

    <p>They require a special enzyme called flippase to translocate them across the ER membrane to the cytosolic side</p> Signup and view all the answers

    What nucleotide is used to help with the addition of a head group to phosphatidic acid?

    <p>Cytosine</p> Signup and view all the answers

    Where does the synthesis of glycerol-3-phosphate occur?

    <p>In the liver</p> Signup and view all the answers

    How is phosphatidylcholine formed from phosphatidylethanolamine?

    <p>By addition of 3 methyl groups donated by S-adenosylmethionine (SAM)</p> Signup and view all the answers

    Which step in cholesterol synthesis is catalyzed by HMG CoA reductase?

    <p>Step 1</p> Signup and view all the answers

    What is the main regulatory enzyme in the cholesterol synthesis pathway?

    <p>HMG CoA reductase</p> Signup and view all the answers

    How many acetyl CoA molecules are needed to make squalene?

    <p>6</p> Signup and view all the answers

    Which step in cholesterol synthesis involves the conversion of mevalonate into activated isoprenes?

    <p>Step 2</p> Signup and view all the answers

    How many acetyl CoA molecules are needed to make Mevalonate?

    <p>3</p> Signup and view all the answers

    What is the main regulatory step of cholesterol synthesis?

    <p>Condensation of 3 acetyl CoA into Mevalonate</p> Signup and view all the answers

    How is HMG CoA reductase regulated in cholesterol synthesis?

    <p>Reversible covalent modification</p> Signup and view all the answers

    What promotes de-phosphorylation of HMG CoA reductase, activating the enzyme?

    <p>Insulin</p> Signup and view all the answers

    What promotes phosphorylation of HMG CoA reductase, inhibiting the enzyme?

    <p>Glucagon</p> Signup and view all the answers

    What happens to the transcription of HMG CoA reductase gene when intracellular cholesterol levels are high?

    <p>Decreases</p> Signup and view all the answers

    Which structural group does cholesterol belong to?

    <p>Isoprenoid</p> Signup and view all the answers

    Which organs of the body contribute most significantly to cholesterol synthesis?

    <p>Liver and kidney</p> Signup and view all the answers

    Where does cholesterol synthesis occur inside the cell?

    <p>Endoplasmic reticulum</p> Signup and view all the answers

    What are the basic steps of cholesterol synthesis?

    <p>Condensation of 3 acetyl CoA into mevalonate, Formation of isopentenyl pyrophosphate, Creation of squalene</p> Signup and view all the answers

    What is the role of the key regulatory enzyme HMG CoA reductase in cholesterol synthesis?

    <p>Condensation of 3 acetyl CoA into mevalonate</p> Signup and view all the answers

    What influences the activity of HMG CoA reductase in cholesterol synthesis?

    <p>Insulin and glucagon</p> Signup and view all the answers

    What inhibits HMG CoA reductase in cholesterol synthesis?

    <p>High intracellular levels of cholesterol</p> Signup and view all the answers

    What are the main components of cholesterol?

    <p>Fused rings with various substituents</p> Signup and view all the answers

    What are sterols?

    <p>Complex molecules made from 6 isoprene units</p> Signup and view all the answers

    What is the function of cholesterol in the cell membrane?

    <p>To provide structural support</p> Signup and view all the answers

    More Quizzes Like This

    Phospholipid Bilayer Structure
    10 questions
    Biochemistry LE 3: Complex Lipids
    41 questions
    Lipid Bilayers and Their Components
    8 questions
    Use Quizgecko on...
    Browser
    Browser