Cellular Membrane Lipids Quiz

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Questions and Answers

What is the precursor of steroid hormones, vitamin D, and bile acids?

  • Flippases
  • Phospholipids
  • Cholesterol (correct)
  • Sphingolipids

Which lipid is the simplest phospholipid?

  • Sphingolipid
  • Cholesterol
  • Flippase
  • Phospholipid (correct)

What are the structural features shared by phospholipids, sphingolipids, and cholesterol?

  • Amphipathic nature
  • Steroid structure
  • Hydrophilic heads and hydrophobic tails (correct)
  • Carbon rings

Which lipid is formed by the combination of two phospholipids?

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

What are the functions of flippases in cells?

<p>Aiding in lipid transport between membrane leaflets (C)</p> Signup and view all the answers

Which biochemical property is associated with lipid rafts in cellular membranes?

<p>Rich in sphingolipids and cholesterol (A)</p> Signup and view all the answers

What is the rate limiting step in bile acid synthesis?

<p>Conversion of cholesterol to 7-alpha hydroxycholesterol (D)</p> Signup and view all the answers

When intracellular cholesterol levels are low, is HMG CoA reductase phosphorylated or unphosphorylated?

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

Where is SCAP-SREBP located when cholesterol levels are low?

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

What is the mechanism of action of statins?

<p>Inhibition of cholesterol synthesis by targeting HMG CoA reductase (B)</p> Signup and view all the answers

Which organ STORES bile acids and bile salts?

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

What is the common feature among all cellular membrane lipids?

<p>Exposed polar head group (D)</p> Signup and view all the answers

Which lipid class is primarily synthesized in the Golgi apparatus?

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

What is the function of lipid flippases in cellular membranes?

<p>Move lipids to the inner leaflet (D)</p> Signup and view all the answers

Which lipid is the only phospholipid that is antigenic, meaning it is immunogenic?

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

In apoptosis, what is one of the hallmarks observed on the outer face of the plasma membrane?

<p>Exposure of phosphatidylcholine (C)</p> Signup and view all the answers

What is the primary difference between apoptosis and necrosis?

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

'Ceramide' in sphingolipids consists of which two components attached by an amide linkage?

<p>'Sphingosine and fatty acid' (B)</p> Signup and view all the answers

'Phosphatidylethanolamine' belongs to which class of lipids?

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

'Mitomycin C' is known for inducing which process in cells?

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

What is the function of 'Scramblase' in cellular membranes?

<p>Move lipids bi-directionally (C)</p> Signup and view all the answers

What is the function of phosphatidylserine exposure during apoptosis?

<p>Recognition and uptake of apoptotic cells by phagocytes (A)</p> Signup and view all the answers

Which process moves phosphatidylserine from the cytoplasmic face to the extracellular face of the plasma membrane during apoptosis?

<p>An ATP-dependent scramblase (A)</p> Signup and view all the answers

What is a characteristic feature of lipid rafts in cellular membranes?

<p>Ordered regions distinct from disordered non-raft regions (A)</p> Signup and view all the answers

What is the role of lipid rafts in cellular functions?

<p>Immune receptor signaling (B)</p> Signup and view all the answers

How does phosphatidylserine on apoptotic bodies help in clearance by phagocytes?

<p>Triggering engulfment by phagocytes (A)</p> Signup and view all the answers

What type of proteins specifically partition to lipid rafts?

<p>Proteins with lipid anchors or modifications (C)</p> Signup and view all the answers

Which organelle is primarily responsible for the synthesis of cholesterol?

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

What is the primary function of HMG CoA reductase in cholesterol synthesis?

<p>Regulate the rate-limiting step of cholesterol synthesis (B)</p> Signup and view all the answers

Which enzyme is responsible for the two-step cleavage of SREBP during cholesterol synthesis regulation?

<p>Protease 2 (A)</p> Signup and view all the answers

What is the role of SCAP (SREBP Cleavage Activating Protein) in cholesterol synthesis regulation?

<p>Senses intracellular cholesterol levels (C)</p> Signup and view all the answers

How do statins primarily affect cholesterol synthesis?

<p>Competitively inhibit HMG CoA reductase (C)</p> Signup and view all the answers

What effect does glucagon have on HMGR expression and activity?

<p>Inhibits HMGR expression and activity (B)</p> Signup and view all the answers

Which drug primarily acts at the small intestine brush border to inhibit cholesterol absorption?

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

What is a key advantage of using Zetia (ezetimibe) in reducing cholesterol levels?

<p>Does not have significant side effects (C)</p> Signup and view all the answers

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