L02- Proteins and Their Functions 🩺

• What are the learning outcomes of the study material?

  • Define and describe different levels of protein structure with examples.
  • Explain how protein structure is related to its function and is dynamic.
  • Describe ways in which proteins are regulated.
  • Describe how proteins are synthesized and trafficked.
• What connects amino acids in proteins?

  Amino acids are connected by peptide bonds.
• What determines the properties of amino acids?

  The 'R-groups' determine amino acid properties.
• What are the types of secondary structure in proteins?

  • Alpha helix: Stabilized by hydrogen bonds, R groups face outwards. Transmembrane Proteins
  • Beta sheet: Stabilized by hydrogen bonds, R groups are perpendicular to the plane of hydrogen bonding.Parsllel or Anti Parallel
• What is the primary function of cell membranes in most tissues?

  To establish distinctive internal environments that enable cells to thrive
• How do cell membranes achieve the establishment of distinctive internal environments?

  By selectively concentrating various combinations of charge-carrying particles within the intracellular compartment

  
• What types of particles do cell membranes selectively concentrate?

  Species of charge-carrying particles
• What results from the concentration differences of charge-carrying ions between intracellular and extracellular compartments?

  An electrical potential between the intra- and extracellular compartments
• What are the two compartments defined by the cell membrane?

  • Intracellular compartment: largely aqueous environment within the cell
  • Extracellular compartment: also known as interstitium or interstitial space, largely aqueous environment outside the cell

  
• What is the concentration of Na+ inside a typical nerve cell?

  15 mM
• What is the concentration of K+ outside a typical nerve cell?

  1. 5 mM
• What is the resting membrane potential (RMP) of nerve cells?

  Around -65 mV to -70 mV with respect to the outside of the cell
• What does it mean for a cell to be electrically polarized?

  It means there is a separation of charge between the inside and outside of the cell
• What are the two gradients established by the concentration differences of ions across the cell membrane?

  1. Chemical gradient: concentration gradient of ions between intracellular and extracellular compartments
  2. Electrical gradient: electrical potential difference due to the charge of ions

  
• What is the combined term for the chemical and electrical gradients across a cell membrane?

  Electro-chemical gradient
• What characterizes electrically excitable tissues?

  They can momentarily discharge the standing electrical potential between intracellular and extracellular compartments
• How does the discharge of the standing electrical potential function in nervous tissues?

  It serves as a mechanism of electrical communication between cells
• What happens to the resting membrane potential during the process of death in electrically excitable tissues?

  • Permanent discharge of resting membrane potentials occurs
  • Affected tissues include:
  • Nerve Cells
  • Muscle Cells (e.g., cardiac tissue)
  • Glandular Tissues

  
• What are ion channels?

  Protein assemblies lodged within the cell membrane that facilitate passive movement of ions
• What is the function of ion pumps in the cell membrane?

  To maintain the resting membrane potential
• What energy source do ion pumps require to maintain the resting membrane potential?

  ATP
• What factors determine whether particles can cross the cell membrane?

  • Size of the particles
  • Electrical charge on the particles
  • Recognition by specialized transport systems
  • Solubility of molecules in water

  
• What are the types of ion channels commonly studied?

  • Voltage-gated ion channels
  • Ligand-gated ion channels
  • Mechanically-gated ion channels
  • Non-gated ion channels
  • Leak channels
• What is the role of selective ion channels?

  They allow specific ions to cross through their pores
• What distinguishes a given species of ion channel from others?

  Its functional peculiarities, such as which ions they conduct and their gating mechanisms
• What is the concentration of Ca2+ inside a typical nerve cell?

  $<10^{-7} \text{ mM}$
• What is the concentration of Cl- outside a typical nerve cell?

  125 mM
• What is the concentration of K+ inside a typical nerve cell?

  150 mM
• What is the concentration of Na+ outside a typical nerve cell?

  150 mM
• Basic structure of proteins

  NCC

  amino group -NH2

  r group and hydrogen

  carboxyl group -COOH. The central C- The Alpha C
• Tertiary Structure

  Lowest energy

  globular proteins - hydrophobic inside

  Bobds -VDW-hyd-disulph-electro int

  polar and non polar side chains
• 3 types of tertiary structure interactions

  Backbone to back bone

  back bone to side chain

  side chain to side chain
• Quartenery


  More than 1 AA chain
• Who is the author of the study material on proteins and their functions?

  Dr. Victoria Heath
• What is the primary focus of the study material?

  It reviews protein structure and functions.
• What are the learning outcomes of the study material?

  • Define and describe different levels of protein structure
  • Explain how protein structure is related to function
  • Describe ways in which proteins are regulated
  • Describe how proteins are synthesized and trafficked
• What connects amino acids in proteins?

  Peptide bonds
• What determines the properties of amino acids?

  The 'R-groups'
• Which type of amino acids would interact with the hydrophobic interior of the plasma membrane?

  Amino acids with hydrophobic R-groups
• What stabilizes the secondary structure of proteins?

  • Hydrogen bonding between hydrogen and oxygen atoms in peptide bonds
  • Alpha helix and beta sheet are common forms