RBC Membrane Biochemistry

  1. What is the morphology of spherocyte?
    Not biconcave, more spherical shape
  2. What is the characteristic of elliptocyte?
    retains biconcave shape but disc becomes elliptical (Stretched)
  3. What is the difference between echinocyte and acanthocyte?
    echinocytes have small regular spaced projections while acanthocytes have large irregular spaced large projections
  4. T/F: sickle shaped is classified as poikilocyte, along with basically all other morphologies
  5. T/F: Malaria, Plasmodium falciparum, reproduce in red blood cells, so carriers of thalassemia (decreased synthesis of globin) are protected against Plasmodium falciparum malaria. Basically, mutation of membrane metabolism or protein of red blood cell helps protect against malaria.
  6. Biconcave shape of red blood cells corresponds with ______ surface to volume ratio. How does this affect gas exchange, and flow through vasculature?
    Increased; this enhances efficient gas exchange and flow through arteries by providing more flexibility especially for when blood travels to the spleen
  7. T/F: Spherocytes have the highest possible surface to volume ratio
    False; spherocytes have the least possible surface to volume ratio and it is not flexible at all, will lyse if distorted
  8. What are the two layers that make up the RBC membrane?
    • Lipid bilayer containing phospholipid and cholesterol
    • Flexible fibrous protein meshwork composed of spectrin
  9. What links the two layers of RBC membrane together?
    ankyrin complex and 4.1 complex (aka actin or junctional complex) anchor the lipid and spectrin layers together
  10. Spectrin contains many repeats which are in _____ bundles. There is alpha and beta spectrin connect in a head-to-tail orientation in the middle where beta spectrin ___ terminal binds to ___ terminal of alpha spectrin
    • Triple helical
    • Beta- C terminal
    • Alpha -N terminal
  11. Spectrin dimers are ____ (polarity), spectrin tetramers are ____ (polarity)
    • Polar
    • Apolar
  12. Ends of spectrin tetramer building blocks are linked together by _______ complexes by interacting with ____ to form ___ lattice
    • 4.1 to junctional
    • Actin
    • Hexagonal
  13. Which is the most prevalent membrane protein in a red blood cell and what does it do?
    • Band 3 is the most prevalent, it is an anion exchanger aka AE
    • Ankyrin binds to Band3 tetramers to link beta spectrin to ankyrin complexes and thereby the lipid bilayer
  14. What is the function of protein 4.1?
    Protein 4.1 and actin together stabilize and link spectrin tetrameric junctions to the Band3 dimers (in the lipid bilayer) in junctional complexes
  15. What is the function of ankyrin?
    Anchors beta spectrin to ankyrin complex
  16. Where can proteins 4.1 and 4.2 be foud?
    • Protein 4.2 can be found in both complexes (ankyrin and junctional) = think 2 for BOTH complex
    • Protein 4.1 anchors spectrin junctions to actin in just one complex= think 1 for just one complex
  17. Hereditary spherocytosis is _______ linking, meaning the mutation interferes with:
    Vertical (spherical shape cell, so think the cell get elongated up-down direction); mutation interferes with protein lattice to the lipid bilayer, causing the membrane to separate from the spectrin skeleton but does not interfere with th overall structure of the spectrin skeleton
  18. Hereditary elliptocytosis is _____ linking, meaning the mutation interferes with:
    Horizontal linking (elliptical shape, so think the rbc getting stretched to the sides); mutation causes spectrin skeleton to break apart, but leaves the lattice attach to the membrane
  19. Which hereditary RBC morphological change affect ankyrin and band3?
    Hereditary spherocytosis
  20. T/F: failure to link spectrin skeleton to the lipid bilayer allows for loss of lipids by vesiculation leading to spherocytes
  21. Spherocytes (lack/ does not lack) central pallor, and it is (hyperchromic/ hypochromic)
    • Lack central pallor
    • Hyperchromic (tiny solid red ball)
  22. T/F: Hereditary elliptocytosis biconcave shape stays because the spectrin skeleton is still linked to the lipid bilayer, unlike in hereditary spherocytosis where the linkage is disrupted
  23. Hereditary spherocytosis and elliptocytosis fall under which category of anemia?
    Normocytic, specifically hemolytic anemia- this is because the MCV is still within normal limits, just there is more destruction of these stupidly shaped cells causing anemia
Card Set
RBC Membrane Biochemistry
HemeOnc Midterm