Cell Biology Lecture Week 3
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Questions and Answers

What is the main function of transport proteins present in the plasma membrane?

  • Actively bringing things in or sending things out (correct)
  • Initiating cell-to-cell adhesion
  • Participating in signaling processes
  • Serving as sites for specific proteins

    • Which macromolecule is NOT mentioned as a component of membranes in the text?

  • Lipids
  • Nucleic Acids (correct)
  • Proteins
  • Carbohydrates

    • Where are carbohydrates typically found in relation to membranes?

  • Attached to either lipids or proteins (correct)
  • Located within the nucleus
  • Only in the cytoplasm of the cell
  • As part of the plasma membrane structure

    • A phospholipid has three fatty acid tails.

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

    Phospholipids contain a phosphate group (which is negatively charged).

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

    Phospholipids have a variable head group, which is polar in nature and will interact with aqueous environments.

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

    Phospholipids are amphipathic.

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

    What is the term used for the constant spinning of a phospholipid on its axis?

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

    How does unsaturated fatty acids impact membrane fluidity?

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

    What is the role of cholesterol in membrane fluidity at warm temperatures?

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

    Which type of motion involves two phospholipids swapping places within the same leaflet?

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

    How do longer hydrocarbon chains in fatty acids affect membrane fluidity?

    <p>Make membranes less fluid (D)</p> Signup and view all the answers

    What is the main characteristic of phospholipids that allows them to spontaneously form a bilayer in an aqueous environment?

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

    Which type of phosphoglyceride has a head group of choline?

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

    What is the major structural difference between phosphoglycerides and phosphosphingolipids?

    <p>Type of backbone (A)</p> Signup and view all the answers

    How many fatty acid chains do phosphosphingolipids typically have?

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

    Who made the discovery that phospholipids form a bilayer in 1925?

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

    Phosphoglycerides and sphingolipids are examples of phospholipids.

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

    Which feature is true for sphingolipids?

    <p>Single fatty acid chain that is longer than those found in phosphoglyceride (C)</p> Signup and view all the answers

    A membrane will be more rigid if it has many unsaturated fatty acids.

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

    What is the defining characteristic of integral membrane proteins?

    <p>They penetrate into the hydrophobic region of the bilayer (A)</p> Signup and view all the answers

    Which type of protein is usually attached to glycolipids called GPI?

    <p>Lipid-anchored proteins (A)</p> Signup and view all the answers

    What is the key characteristic of lipid rafts within the membrane?

    <p>Sequester signaling proteins due to unique lipid composition (D)</p> Signup and view all the answers

    Oligosaccharides are only ever found attached to proteins or lipids.

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

    What type of bond is found between monomers in a polysaccharide?

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

    In membrane biology, what is the term used when sugar is attached to an asparagine amino acid residue?

    <p>N-linked glycosylation (C)</p> Signup and view all the answers

    What determines blood type in red blood cell membranes?

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

    Which of the following is NOT a reason why proteins may not move freely in the cell membrane according to the text?

    <p>Protein linked to ribosomes (B)</p> Signup and view all the answers

    What type of glycosylation occurs when sugar is attached to a serine or threonine amino acid residue?

    <p>O-linked glycosylation (A)</p> Signup and view all the answers

    What was demonstrated by Larry Frye and Michael Edidin in the 1970s regarding membrane protein movement?

    <p>Some membrane proteins move (D)</p> Signup and view all the answers

    What is the main characteristic of epithelial cells mentioned in the text?

    <p>They are very organized with two clear ends. (D)</p> Signup and view all the answers

    Which proteins are primarily responsible for attaching cells together in adherens junctions?

    <p>Cadherins, catenins, and actin cytoskeleton (C)</p> Signup and view all the answers

    What is the role of cadherins in cell junctions?

    <p>Mediate attachment between cells (A)</p> Signup and view all the answers

    Which type of junction is specifically mentioned as being highly prominent in epithelial cells?

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

    What is the function of plasmodesmata in plant cells?

    <p>Transporting water and nutrients between cells (B)</p> Signup and view all the answers

    What is the main function of desmosomes in tissues?

    <p>Provide structural integrity (A)</p> Signup and view all the answers

    Which type of proteins make up tight junctions?

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

    What is the main role of elastin in tissues?

    <p>Confer elasticity/flexibility (B)</p> Signup and view all the answers

    Which of the following is NOT a component of the extracellular matrix?

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

    What is the primary role of cell walls in plant cells?

    <p>Provide a permeability barrier for large molecules (D)</p> Signup and view all the answers

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