Biochemistry Lecture 1: Cell Membrane Structure
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Questions and Answers

What is the primary role of BAR domain proteins in vesicle budding?

  • They infuse energy into the vesicle release process.
  • They shape the plasma membrane to facilitate clathrin recruitment. (correct)
  • They initiate the formation of clathrin-coated vesicles.
  • They directly pinch off the vesicle from the membrane.

    • Dynamin requires GTP to induce shape changes necessary for vesicle release.

    True

    What is responsible for recruiting local assembly of actin filaments during vesicle budding?

    Clathrin machinery

    The crescent-shaped BAR domains interact with the lipid head groups via __________ interactions.

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

    Match the following components to their functions:

    <p>Clathrin = Coat formation for vesicles Dynamin = Vesicle release BAR domain proteins = Membrane shaping Actin filaments = Providing tension during vesicle pinching</p> Signup and view all the answers

    Which of the following factors contribute to increased insulin resistance?

    <p>All of the above</p> Signup and view all the answers

    What is the role of lipid rafts in receptor function?

    <p>To keep components of the receptors together for ligand binding</p> Signup and view all the answers

    Insulin is commonly used in treating type 2 diabetes.

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

    What effect does GLP-1 have on insulin release?

    <p>Increases insulin release</p> Signup and view all the answers

    G protein-coupled receptors have a single transmembrane domain.

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

    Blocking the Na channel in renal glucose handling leads to more glucose being in the ______.

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

    What is the function of secondary messengers like cyclic AMP in signal transduction?

    <p>To activate protein kinases</p> Signup and view all the answers

    The ________ subunit of G protein-coupled receptors binds to GDP or GTP.

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

    Match the following diabetes treatments to their effects:

    <p>Incretin drugs = Increase insulin release and aid in weight loss Statin drugs = Reduce cardiovascular risk GLP-1 = Improves insulin sensitivity and creates a feeling of fullness Na channel blockers = Increase glucose in urine</p> Signup and view all the answers

    Match the following receptor types with their descriptions:

    <p>Channel linked receptors = Allow ions to pass through the membrane Enzyme linked receptors = Transmit signals inside the cell through enzyme activity G protein-coupled receptors = Activate intracellular signaling through G proteins Ion channel receptors = Open to allow ion movement in response to a ligand</p> Signup and view all the answers

    What is the primary role of NADPH?

    <p>Biosynthetic reactions</p> Signup and view all the answers

    Glycolysis is an anabolic pathway that builds molecules.

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

    What are the two phases of the Pentose Phosphate Pathway?

    <p>Oxidative Phase and Nonoxidative Phase</p> Signup and view all the answers

    Glucose is largely obtained from the _____?

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

    Match the following glucose transporters with their characteristics:

    <p>Glucose transporter 1 = Transport of glucose in the brain Sodium-glucose cotransporter = Active transport of glucose with sodium Glucose transporter 2 = Facilitates glucose transport in the liver Glucose transporter 4 = Insulin-responsive glucose uptake in muscles and fat cells</p> Signup and view all the answers

    Which type of signaling involves signals released into the extracellular space?

    <p>Paracrine signaling</p> Signup and view all the answers

    Endocrine signaling occurs in a fixed space and has regulatory effects.

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

    What is the primary purpose of secondary messengers in cell signaling?

    <p>To interpret signals and facilitate signaling cascades.</p> Signup and view all the answers

    In signaling cascades, __________ removes the phosphate from proteins.

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

    Match the type of cell communication with its description:

    <p>Contact-dependent = Requires direct interaction between cells Endocrine = Signals travel long distances in the bloodstream Paracrine = Signals affect nearby cells Neurotransmitter = Signals bind to receptors on adjacent cells</p> Signup and view all the answers

    Which of the following outcomes can cell communication affect?

    <p>All of the above</p> Signup and view all the answers

    The signaling cascade can only activate proteins in the cytoplasm.

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

    What role do kinases play in the phosphorylation process?

    <p>Kinases add phosphate groups to proteins.</p> Signup and view all the answers

    What happens to the membrane during apoptosis?

    <p>The membrane starts blebbing and becomes more fluid</p> Signup and view all the answers

    During early apoptosis, sphingomyelin translocates from the outer membrane to the inner membrane.

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

    What role do ER trackers play in studying cell apoptosis?

    <p>They help in quantifying the number of vesicles generated.</p> Signup and view all the answers

    Propidium iodide enters the cell when apoptosis is occurring, and its presence indicates _____ cell viability.

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

    Match the following signaling pathways with their functions:

    <p>Acetylcholine = Synapse transmission Insulin = Glucose metabolism Endocrine signaling = Hormonal signal release Apoptosis signaling = Cell death regulation</p> Signup and view all the answers

    What triggers the activation of scramblases during apoptosis?

    <p>Release of Ca from the ER</p> Signup and view all the answers

    Flow cytometry provides higher spatial resolution than confocal microscopy.

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

    What is one advantage of using flow cytometry for studying cell populations?

    <p>It allows for rapid quantification of multiple parameters in large cell populations.</p> Signup and view all the answers

    Study Notes

    Biochemistry Notes - Lecture 1

    • Membranes are composed of phospholipids
    • Phospholipids interact with each other and the aqueous compartments to form a bilayer membrane
    • The fluid mosaic model describes the structure of cell membranes
    • Cholesterol is a component of cell membranes that provides stability
    • Diffusion within membranes affects lipids and proteins
    • The lipid bilayer is a fragile barrier
    • Interactions between membrane components maintain its integrity
    • Components of the cell membranes include:
      • Phospholipids
      • Cholesterol
      • Proteins
      • Glycoproteins
      • Glycolipids
    • Phospholipids have 2 fatty acid chains, glycerol, and a highly polar or charged group
    • They are amphipathic
    • Sterols, such as cholesterol, have 4 ring structures at the centre and saturated hydrocarbon tails
    • Cholesterol is generated in the liver from acetyl-CoA
    • Cholesterol is made in the smooth endoplasmic reticulum of hepatocytes
    • Hepatocytes produce cholesterol→ bile→ large intestine→ reabsorbed
    • Cholesterol is lipophilic
    • Cholesterol is essential for the synthesis of bile acids, without bile acids there is no breakdown of fatty acids
    • Bile acids are amphiphilic and enable the solubilization of dietary fats (emulsification)
    • Emulsification is important for the uptake of dietary fats
    • Bile acids increase the surface area for lipid digestion

    Biochemistry Notes - Lecture 1, continued

    • Lipid-soluble hormones include: cortisol, aldosterone, testosterone, T3, and T4
    • Hormones bind to receptors and activate genes; this takes more time compared to activating a protein.
    • Bile acids are synthesized from cholesterol
    • Bile acids are essential for lipid digestion and increase the solubility of lipids
    • Bile acids increase the surface area for lipid digestion
    • Cholesterol is used to produce bile acids
    • Bile acids enable digestion of lipids by solubilizing the fats into the small intestines
    • Primary bile acids include: cholic acid, chenodeoxycholic acid, deoxycholic acid, and lithocholic acid
    • Primary bile acids are produced by the liver, usually conjugated in the body, and modified in the gut by bacteria
    • Secondary bile acids are less toxic, being modified by conjugation, often linking to molecules with waste or toxic products.
    • Bile is crucial for lipid digestion, making the fats more water soluble

    Biochemistry Notes - Lecture 1, continued

    • Fatty acids are commonly found, trans fatty acids are obtained from diet
    • Phospholipid tails can be saturated or unsaturated

    Biochemistry Notes - Lecture 2

    • Cholesterol is a component of lipoproteins, which transport lipids in the body
    • Lipoproteins contain a hydrophobic core (triacylglycerol and cholesterol esters) and an amphipathic coat of phospholipids and apolipoproteins
    • Chylomicrons, VLDL, IDL, and LDL are lipoproteins that carry lipids
    • LDL returns to the liver to deliver cholesterol to other tissues that need it
    • Apolipoproteins act as signals for cellular uptake and metabolism
    • LDL recycles to the liver for metabolism and cholesterol use
    • Cholesterol is stored in adipocytes and can be metabolized in cells

    Biochemistry Notes - Lecture 2, continued

    • Metabolized fatty acids are converted to acetyl CoA, which enters the Krebs cycle or can be stored if in excess
    • Fatty acids can be converted into chylomicrons to travel through the body
    • Phospholipids are amphipathic molecules that are involved in carrying lipids
    • Lipoproteins are important for carrying lipids through the body

    Biochemistry Notes - Lecture 3

    • Signal transduction involves extracellular signals like hormones binding to receptors triggering intracellular changes (including changes in cell shape or activation of enzymes), allowing a cell-to-cell communication
    • Signal molecules diffuse to receptors nearby
    • Examples of signaling pathways include acetyl choline, glucose, insulin, and apoptosis

    Biochemistry Notes - Lecture 4

    • Lipids and proteins are the major membrane components
    • Membrane asymmetry refers to the different compositions and orientations of lipids on each leaflet within the membrane
    • Cholesterol, flippase, floppase, and scramblase are involved in maintaining membrane asymmetry and composition

    Biochemistry Notes - Lecture 5

    • Lipids can be hydrophobic (tails) or hydrophilic (heads)
    • Lipids form a bilayer structure with the hydrophobic tails in the inside
    • Protein is also an integral part of the membrane

    Biochemistry Notes - Lecture 6

    • Various factors have the potential to affect the rate of diffusion through a membrane
    • The way in which lipid molecules are organized directly affects the proteins that are associated with the membrane

    Biochemistry Notes - Lecture 7

    • There are different types of membrane proteins that can be directly associated with the membrane (integrated into)
    • Membrane proteins have several functions that depend on their types
    • There are multiple pathways for molecules to enter a membrane
    • Cholesterol, and other factors like temperature affect the fluidity of the membrane

    Biochemistry Notes - Lecture 8

    • Glycolysis is a metabolic pathway used to breakdown glucose
    • The pentose phosphate pathway is a pathway used to produce NADPH and phosphorylated sugars
    • NADPH is an important electron carrier in biosynthetic reactions

    Biochemistry Notes - Lecture 9

    • The Pentose Phosphate pathway plays an important role in cell reactions, and can be used for various purposes depending on the needs of the cell.

    Biochemistry Notes - Lecture 10, continued

    • NADPH and NADH are similar but play different roles.
    • The structure and location within the cells can be different
    • Different forms of glucose can be produced depending on the cellular need

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    Biochemistry Notes - Lecture 1 - Membranes

    Description

    Explore the fundamental concepts of cell membranes as discussed in Biochemistry Lecture 1. This quiz covers the composition, structure, and functions of phospholipids, cholesterol, and membrane components, as well as the fluid mosaic model. Test your knowledge on the intricate details that contribute to membrane integrity and functionality.

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