Medical Foundations 1

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blake
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229981
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Medical Foundations 1
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2013-08-16 15:37:44
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Ohio State University College Medicine
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Ohio State University College of Medicine study notes
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  1. What are the main differences between prokaryotes and eukaryotes?
    Eukaryotes have a nucleus, histones, and the mRNA is capped, has a polyA tail, and introns. Prokaryotes do not.

    Also, prokaryote transcription and translation are coupled and (like eukaryote germ cells) they have a single copy of their DNA (haploid genome). Somatic Eukaryote DNA is diploid.
  2. What are the major steps for creating functional proteins from DNA?
    • Transcription,
    • RNA processing (capping, splicing, PolyA addition, and editing),
    • export (to cytoplasm),
    • translation, and
    • post translation modifications.
  3. List 3 types of physical DNA modifications
    • 1) DNA/gene loss: Genes are partially or completely deleted so a protein is not made.
    • 2) DNA/gene amplification: Causes a large amount of the protein to be made.
    • 3) DNA rearrangement: Segments of DNA are moved around, like in immunoglobulins from B cells.
  4. List 3 types of chemical DNA modifications
    • 1) Methylation: A methyl is added at cytosine resides, reducing transcription.
    • 2) Acetylation
    • 3) Sumoylation: Post-transcriptional change: Small Ubiquitin-like Modifiers. (Actually affects proteins, not DNA)
  5. List 2 types of transcriptional regulation by proteins
    • 1) Chromatin condensation by histone (preventing transcription).
    • 2) Regulation by transcription factors (like steroid hormones).
  6. List 5 types of post-transcriptional regulation
    • 1) Alternative splicing: selecting different exons to code different proteins from the same DNA
    • 2) Alternative polyadenylation: adds the polyA tail at a different site, shortening the mRNA or coding for a different protein
    • 3) mRNA editing:
    • 4) mRNA transport: (to the cytoplasm for translation - required in eukaryotes).
    • 5) mRNA stability: Ex. When iron is low, transferrin receptor mRNA is stabilized so it can produce more receptors.
  7. Explain the regulatory process for globin gene expression.
    • -Methylation prevents the production in cells that do not make hemoglobin
    • -Chromatin condensation prevents maturing RBCs from transcribing
    • -Gene loss (complete) prevents mature RBCs from producing proteins
    • -Translational regulation controls the translation of any remaining globin mRNA based on the presence of heme.
  8. Name 3 inhibitors of transcription and note what kind of cells they affect
    • 1) Actinomycin D: Prokaryotes and eukaryotes
    • 2) Rifamycin or rifampicin: Prokaryotes
    • 3) α-amanitin: Eukaryotes
  9. List 7 prokaryotic translation inhibitors
    • Tetracycline
    • Chloramphenicol
    • Erythromycin
    • Streptomycin
    • Neomycin
    • Kanamycin
    • Gentamycin
  10. List 3 eukaryotic translation inhibitors
    • Cycloheximide
    • Diphtheria toxin
    • Ricin
  11. Name an inhibitor of both prokaryotes and eukaryotes
    Puromycin
  12. Which process do snRNPs regulate?
    Splicing. They help form spliceosomes.
  13. What is the cause of Chronic myelogenous leukemia (CML)?
    A DNA rearrangement (translocation) between chromosomes 9 and 22.
  14. What are thalassemias?
    Any mutation that causes the globin protein (either α or β chain) to be dysfunctional or causes a decreased expression of globin gene, causing anemia.  This is the most common form of hereditary anemia.
  15. List 3 allosteric effectors of Hb function
    • 1) pH: increased pH causes increased O2 release.
    • 2) The intracellular concentration of bisphosphoglycerate within the RBC: BPG causes stability, so CO2 is released more readily at the lungs and O2 at the tissues. A lack of BPG causes the affinity curve to look less cooperative, much like HbF which has less BPG.
    • 3) C02:
  16. What is required for Sickle Cell Anemia to occur?
    The patient must have the sickle cell anemia mutation in one gene, and an affected second gene. Ex: HbSS (both Hb genes have S.C.A.), HbS/B (the other has ß thalassemia), or Hb SC, SD, etc.
  17. What should you do if an infant tests positive for sickle cell disease?
    Perform further testing (complete blood count and hemoglobin electrophoresis). If positive, refer them to a hemoglobinopathy clinic and begin penicillin right away. Most sickle cell deaths occur between ages 1-3. An infection can result in a strong reaction or a stroke.
  18. Erythropoiesis pathway
    JAK2
  19. What does flipase do?
    Rapidly transports phosphatidylserine and ethanolamine from the external surface to the internal membrane.
  20. What does flopase do?
    Slowly transports phospholipids back from the inner membrane to the external surface.
  21. What does scramblase do?
    Moves phospholipids in both directions.
  22. What are the two general types of problems associated with erythrocytes?
    • 1) Quantitative: Too few (anemia) or too many (polycythemia).
    • 2) Qualitative: Normal number of cells with some kind of functional problem (ex. sickle cell). Often called hemoglobinopathies.
  23. What causes hereditary spherocytosis?
    Abnormalities in the ankyrin, band 3, and spectrin genes.
  24. What is this disease?
    Hereditary spherocytosis, characterized by spherical RBCs and increased hemolysis. This may result in the presence of reticulocytes.
  25. What are reticulocytes?
    Immature RBCs that are bluish in color and still posses a nucleus.
  26. What is this disease?
    Hereditary elliptocytosis/ovalcytosis
  27. What causes Hereditary elliptocytosis/ovalcytosis?
    Abnormalities is spectrin, ankyrin, and protein 4.1
  28. What is this disease?
    Hereditary pyropoikilocytosis.
  29. What causes Hereditary pyropoikilocytosis?
    Abnormalities is spectrin, ankyrin, and protein 4.1
  30. What is this disease?
    Hereditary stomatocytosis.
  31. What causes hereditary stomatocytosis?
    Abnormalities in the band 3 gene resulting in increased intracellular sodium.
  32. What are these, and what causes it?
    Bite cells, caused by macrophages due to hemoglobin oxidation caused by G6PD deficiency.
  33. What are these spikey cells, and what causes them?
    Acanthocytes, caused by a pyruvate kinase deficiency resulting in a loss of K+ and water, and an accumulation of Na+.
  34. What are the correct lead locations for an ECG? Note, the first intercostal space is below the first rib, and so on.
  35. What is the life span of erythrocytes and their mechanisms for clearance
    120 days (2 million reticulocytes are produced per second). Removed by macrophages in the reticuloendothelial system (spleen, liver, bone marrow). Sickle cells live 10-20 days.
  36. What is the cytoplasm?
    Everything outside the nucleus.

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