the small subunit binds tRNA and mRNA, the largesubunit forms peptide bonds
binds to large subunit, blockspeptide bond formation, indirectly blocks movement from A to P sites
Ribosomes have Protection proteins (RPP’s) which protectagainst antibiotics. e.g. Tet(O). Tet(O) binds large and small subunits. kicks tetracycline out of A site
Protein degradation required more than one ubiquitinto be added. They are added in a chain. A minimum of 4 ubiquitins needed for protein degradation. (initial one added to lysine of substrate
remove ubiquitin molecules (also called “Deubiquitinatingenzymes” DUBS). They can cleaveubiquitins one, or more than one at a time
nucleus,mitochondria,plasmamembrane,Golgi,peroxisomes, lysosomes, or are retained in the endoplasmic reticulum. Other proteins leave the cell through vesicular transport from the golgi.
H bonds between bases and stacking forcesbetween adjacent base pairs on the spiral stair case of the helix
coiling of the series ofnucleosomes into a helical array to form a fiber of ~30nm. Packing ratio of 40
high predictive value, analytic technique has tobe reproducible, cost must be low, test must support decisions on treatment
22 proteins constitute 99% of total plasmaprotein mass, concentrations below limit of detection byspectrometers. Deplete of majorproteins and improved sensitivity of spectrometers is needed.
Pinocytosis: cell drinking
Receptor mediated endocytosis
Phagocytosis: largeparticles taken in (e.g. bacteria), involves major membrane and cytoskeleton rearrangementsand NRG.
it binds to the collar ofa coated pit (which has lots of clathrin) and pinches off endocytizedvesicles from the plasma membrane. Ituses GTP.
flask shaped pits distinct from coated pits andoccupy ~10% of the surface of endothelial cells. Vesicles also budoff from caveolae during endocytosis but more slowly than from coated pits.
attachment, engulfment, fusion with
lysosomes, and degradation
early endosomes bud offmembrane to their interior to generate multivesicular bodies. MVBs mature into late endosomes that are distinguished by having lower pH and are denser.
Late endosomes fuse with primary lysosomes by a processemploying Rab proteins
Early endosomes recycle back to the cell surface either directly orby passing through the TGN
-Metacentric = p and q of equal length
-Submetacentric = p slightly shorter than q
-Acrocentric = centromere near end of short arm
(P= short arm, Q= long arm)
Stalk = site of ribosomal DNA
-Satellites = small masses of chromatin
Mosaicism may exist for a single gene defect or an entire chromosomeabnormality.
single chromosome composed of two identical copiesof a chromosome arm as mirror images separated by a centromere
5. Bacterialartificialchromosomes(BACs)6. Viralvectors
PCR DNA can be analyzedby restriction enzyme digestion, by size,by sequence analysis. If DNA strands aremade complementary to a virus, such as HIV, PCR can be used to test for viral DNA in blood samples.
massively parallel sequencing of clonallyamplified DNA molecules that are fixed and spatially separated in a flow cell.
microsomal triglyceride transfer protein) lives in ER, transfers lipids from inner membrane to incoming lipoprotein, helps them fold. MTP inhibition lowers cholesterolcause Apo B isn’t made.
binds small ribosome subunit that has a mettRNA bound. whole complexbinds mRNA and moves along til reaches start codon. eIF2 alpha has GTP bound that hydrolyzes whenit reaches start codon
Epimerase deficiency: benign condition. accumulation of UDP-gal. impact on glycoproteinbiosynth
What is the primary role of galactose in metabolism and how is itaffected in galactosemia?
What are the possible reasons for the poor long-term outcome oftreated galactosemics?
Explain the extended elevation of blood fructose concentration inpatients with hereditary fructose intolerance (HFI).
Are fructose-1-phosphate aldolase and fructose-1,6-bisphosphatealdolase the same protein? In what pathway(s) does this enzymefunction?
elevation of these in HFI is result ofthe metabolic probs that occur after eating fructose
Acute, cutaneous, and mixed. Acute is with abdominal pain, constipation,vomiting, and neuropsychiatric disorder. Cutaneous is photosensitivity only.
Why didn’t GeorgeIII have relatives who exhibited a similar autosomal dominantdisorder?
Some of his relatives showed skin sensitivity based upon medical accounts oftheir physicians. The second article now implies that heavy metal poisoning,particularly arsenic, might have contributed to George’s symptoms.
How is lead poisoning related to heme biosynthesis? How would heavy metalsimpair heme biosynthesis?
Lead poisoning inhibits a number of enzymes in the heme biosynthetic pathway,particularly the ferrochetolase, the last step. Heavy metals inhibit enzymes bind to andinactivating sulfhydryl groups, the inhibition would benoncompetitive
Jaundice is not a porphyria. Jaundice is a condition (not a disease) that iscaused by heme breakdown. Have the students describe jaundice to you.
Unclear, but this is a good time to emphasize to students that a differentialdiagnosis is difficult to perform in the absence of a patient
What are three variables that determine the rate and extent of hemoglobinpolymer formation within erythrocytes?
increased oxygen, intracellular HbS concentration, and thepresence or absence of HbF.
for <1% of all hemoglobin in adults. Hemoglobin F gamma chain has a differentamino acid sequence than beta and thus HbF interferes with tactoid formation.
How is sickle cell disease diagnosed clinically? What is the frequency of thedisease in different populations?
High in West African (20-30% carry the gene), AfricanAmerican
What are the general strategies to treat patients with sickle cell disease? Give anexample of each.
These fall into four categories: Inhibition of HbS polymerization, reduction ofintracellular Hb conc., induction of HbF, and, of course, transfusion in severecases.
What is the mechanism by which STI571 (Gleevac) inhibits the Abl tyrosine kinase?
What type of enzyme inhibitor is STI571, and how would its mechanism of actionbe determined experimentally?
Describe the CK enzyme reaction. In what tissues does this reaction occur?
What isozymes are known for CK, and what is their tissuelocation?
Three: CK is a dimer composedof different combinations of monomers, one specific for brain (B) and one specificfor muscle (M). Cardiac muscle has the MB isoform as well as the MM form.
The MM form is found in skeletal muscle.
What is the value of assaying for the CK MB isozyme in cardiology? How is theassay used?
What is the biochemical basis of Menkes disease, i.e. why mutations in the Menkesdisease gene (ATP7A) cause the disease?
associated with deletions, chromosomal rearrangements, or mutationsin the gene ATP7A. causes reduced transport of dietary copper across enterocytes to hepatic portal circulation. Traps Cu in GI tract so it can't get to other places
Explain how normal Menkes disease (ATP7A) and Wilson’s disease (ATP7B) proteinswork and how they regulate copper metabolism. (see slide 352
Menkes disease protein (ATP7A) and Wilson’s disease protein (ATP7B) are the copper-transporting ATPases. large transmembrane proteins that use energy of ATPhydrolysis to transport copper from the cytosol across cell membranes
Both proteins are located in thetrans-Golgi network (TGN) where they transport copper from cytoplasm into the lumen ofTGN for incorporation of copper into secreted copper-dependent enzymes
What are the consequences of HER-2 over expression to intracellular signalingand to behavior of tumor cells?
Why would a medical oncologist be interested in whether or not a patient’s tumor overexpressed HER-2?
HER-2 overexpression predicts responsiveness to trastuzumab.The trastuzumab antibody binds to the ectodomain of HER-2 and modulatesHER-2 actions. Tumor cells that express low levels of HER-2 don’t respond totrastuzumab
What is meant by a “humanized antibody”, and why are humanized antibodiessuch as trastuzumab effective as therapeutics?
Humanized antibodies are effective as therapeutics because hypersensitivityreactions are diminished when most of the antibody consists of human-specific amino acid sequence. antibodies also show very high affinity and specificity
Describe the biochemistry of Gaucher’s disease. Where does the affected enzymefunction on the histological and cellular level? inheritance?
Describe the genetics of Gaucher’s disease. Are mutations in the gene random or arethere specific mutations that predominate?
Gaucher’s is autosomal recessive. Four specific mutations are responsible for most cases in the Ashkenazi Jewish population. Thesemutations are less prominent in other populations. Phenotype does not correlate withgenotype.
What clinical assessments are employed to identify patients who have Gaucher’sdisease?
abnormal hemoglobin levels, Enlarged liver and/orspleen is often seen. Bone marrow biopsy would show gaucher cellsengorged with glycolipid. enzyme assays for glucocerebrosidase would showno or little activity. MRI and CT
Unlike the case with Tay-Sachs disease, Gauchers carriers can not be picked up byenzyme assay screen. Heterozygotes show normal to greatly reduced activity.
How has enzyme replacement therapy (ERT) for Gaucher’s disease progressed overthe years and where does it stand today?
What is the downside of ERT therapy for Gauchers? What other therapy options are available andwhat are their downsides?
“Disease”gene: mutation in a single gene isnecessary and (often) sufficient to cause adisorder
“Susceptibility” gene: mutation in a geneconfers increased risk for a disorder, but isneither necessary nor sufficient, by itself
Acute illness after period of normal behavior and feeding - hours to weeks
Seizures or hypotonia
Unusual body odor, Jaundice, sepsis, vomiting, many more