Ribosome Structure eukaryotes small subunit (40S) synthesized in the nucleus large subunit (60S) synthesized in the nucleolus total = 80S S = sedimentation prokaryotes small subunit (30S) + large subunit (50S) → 70S Catalytic sites A (acceptor) site accepts charged aa-tRNA P (peptidyl) site holds the growing peptide chain and transfers to the aa-tRNA in the A site E (exit) site allows tRNA to exit the ribosome after releasing its amino acid to the aa-peptide chain Forms polysomes single mRNA being translated simultaneously by several ribosomes can be free proteins for nucleus or mitochondria membrane bound found on rough ER proteins for secretion or membrane insertion Steps Initiation initiation complex generated from small ribosomal subunit mRNA 5'-cap (eukaryotes) Shine-Dalgarno sequence (prokaryotes) initiation aa-tRNA met-tRNA (eukaryotes) fmet-tRNA (prokaryotes) initiation factors (IFs) help in assembly released when mRNA joins the ribosomal subunit once assembled, recruits the large ribosomal subunit initiation aa-tRNA occupies the P-site all other aa-tRNAs bind the A-site the A-site is empty Elongation aminoacyl-tRNA binds to A site consumes 1 GTP peptidyl-bond formation peptidyl transferase reaction catalyzed by ribosomal rRNA ("ribozyme") transfers growing polypeptide to amino acid in the A site translocation ribosome moves 3 nucleotides at a time in a 5' to 3' direction moves peptidyl RNA from A site to P site moves empty tRNA from P site to E site for exit A site now empty and ready to accept next aa-tRNA catalyzed by elongation factor-2 (eEF-2) inactivated via ADP-ribosylation by bacterial toxins (Pseudomonas and Diphtheria) consumes 1 GTP cycle is repeated for each amino acid addition to the polypeptide Wobble phenomenon The anticodon of certain tRNA molecules can bind to multiple codons The first two nucleotides of the codon adequately specify which tRNA (and amino acid) binds the codon, thereby permitting multiple nucleotides in the third position to bind the same tRNA. Termination stop codon reached in mRNA release factor binds mRNA peptide bond is hydrolyzed and completed protein is released ribosomal complex dissociates Overall energy requirement 4 high energy bonds ATP to AMP for tRNA charging (2) 2 GTP to GDP for elongation (2) Pharmacologic Inhibition of Prokaryotic Protein Synthesis Bind 30S aminoglycosides inhibit formation of the initiation complex promotes misreading of mRNA Bind 50S chloramphenicol inhibits peptidyl transferase macrolides inhibits translocation clindamycin inhibits translocation References
QUESTIONS 1 of 6 1 2 3 4 5 6 Previous Next Lab Values Blood Hematologic Cerebrospinal Sweat, Urine, and BMI Blood, Plasma, Serum Reference Range ALT 8-20 U/L Amylase, serum 25-125 U/L AST 8-20 U/L Bilirubin, serum (adult) Total // Direct 0.1-1.0 mg/dL // 0.0-0.3 mg/dL Calcium, serum (Ca2+) 8.4-10.2 mg/dL Cholesterol, serum Rec: < 200 mg/dL Cortisol, serum 0800 h: 5-23 μg/dL //1600 h: 3-15 μg/dL 2000 h: ≤ 50% of 0800 h Creatine kinase, serum Male: 25-90 U/LFemale: 10-70 U/L Creatinine, serum 0.6-1.2 mg/dL Electrolytes, serum Sodium (Na+) 136-145 mEq/L Chloride (Cl-) 95-105 mEq/L Potassium (K+) 3.5-5.0 mEq/L Bicarbonate (HCO3-) 22-28 mEq/L Magnesium (Mg2+) 1.5-2.0 mEq/L Estriol, total, serum (in pregnancy) 24-28 wks // 32-36 wks 30-170 ng/mL // 60-280 ng/mL 28-32 wk // 36-40 wks 40-220 ng/mL // 80-350 ng/mL Ferritin, serum Male: 15-200 ng/mLFemale: 12-150 ng/mL Follicle-stimulating hormone, serum/plasma Male: 4-25 mIU/mL Female: premenopause: 4-30 mIU/mL midcycle peak: 10-90 mIU/mL postmenopause: 40-250 pH 7.35-7.45 PCO2 33-45 mmHg PO2 75-105 mmHg Glucose, serum Fasting: 70-110 mg/dL2-h postprandial:<120 mg/dL Growth hormone - arginine stimulation Fasting: <5 ng/mLProvocative stimuli: > 7ng/mL Immunoglobulins, serum IgA 76-390 mg/dL IgE 0-380 IU/mL IgG 650-1500 mg/dL IgM 40-345 mg/dL Iron 50-170 μg/dL Lactate dehydrogenase, serum 45-90 U/L Luteinizing hormone, serum/plasma Male: 6-23 mIU/mL Female: follicular phase: 5-30 mIU/mL midcycle: 75-150 mIU/mL postmenopause 30-200 mIU/mL Osmolality, serum 275-295 mOsmol/kd H2O Parathyroid hormone, serume, N-terminal 230-630 pg/mL Phosphatase (alkaline), serum (p-NPP at 30° C) 20-70 U/L Phosphorus (inorganic), serum 3.0-4.5 mg/dL Prolactin, serum (hPRL) < 20 ng/mL Proteins, serum Total (recumbent) 6.0-7.8 g/dL Albumin 3.5-5.5 g/dL Globulin 2.3-3.5 g/dL Thyroid-stimulating hormone, serum or plasma .5-5.0 μU/mL Thyroidal iodine (123I) uptake 8%-30% of administered dose/24h Thyroxine (T4), serum 5-12 μg/dL Triglycerides, serum 35-160 mg/dL Triiodothyronine (T3), serum (RIA) 115-190 ng/dL Triiodothyronine (T3) resin uptake 25%-35% Urea nitrogen, serum 7-18 mg/dL Uric acid, serum 3.0-8.2 mg/dL Hematologic Reference Range Bleeding time 2-7 minutes Erythrocyte count Male: 4.3-5.9 million/mm3Female: 3.5-5.5 million mm3 Erythrocyte sedimentation rate (Westergren) Male: 0-15 mm/hFemale: 0-20 mm/h Hematocrit Male: 41%-53%Female: 36%-46% Hemoglobin A1c ≤ 6 % Hemoglobin, blood Male: 13.5-17.5 g/dLFemale: 12.0-16.0 g/dL Hemoglobin, plasma 1-4 mg/dL Leukocyte count and differential Leukocyte count 4,500-11,000/mm3 Segmented neutrophils 54%-62% Bands 3%-5% Eosinophils 1%-3% Basophils 0%-0.75% Lymphocytes 25%-33% Monocytes 3%-7% Mean corpuscular hemoglobin 25.4-34.6 pg/cell Mean corpuscular hemoglobin concentration 31%-36% Hb/cell Mean corpuscular volume 80-100 μm3 Partial thromboplastin time (activated) 25-40 seconds Platelet count 150,000-400,000/mm3 Prothrombin time 11-15 seconds Reticulocyte count 0.5%-1.5% of red cells Thrombin time < 2 seconds deviation from control Volume Plasma Male: 25-43 mL/kgFemale: 28-45 mL/kg Red cell Male: 20-36 mL/kgFemale: 19-31 mL/kg Cerebrospinal Fluid Reference Range Cell count 0-5/mm3 Chloride 118-132 mEq/L Gamma globulin 3%-12% total proteins Glucose 40-70 mg/dL Pressure 70-180 mm H2O Proteins, total < 40 mg/dL Sweat Reference Range Chloride 0-35 mmol/L Urine Calcium 100-300 mg/24 h Chloride Varies with intake Creatinine clearance Male: 97-137 mL/minFemale: 88-128 mL/min Estriol, total (in pregnancy) 30 wks 6-18 mg/24 h 35 wks 9-28 mg/24 h 40 wks 13-42 mg/24 h 17-Hydroxycorticosteroids Male: 3.0-10.0 mg/24 hFemale: 2.0-8.0 mg/24 h 17-Ketosteroids, total Male: 8-20 mg/24 hFemale: 6-15 mg/24 h Osmolality 50-1400 mOsmol/kg H2O Oxalate 8-40 μg/mL Potassium Varies with diet Proteins, total < 150 mg/24 h Sodium Varies with diet Uric acid Varies with diet Body Mass Index (BMI) Adult: 19-25 kg/m2 Calculator ( ) xy AC 7 8 9 ÷ 4 5 6 × 1 2 3 - 0 . = + Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK You have 100% on this question. Just skip this one for now. Take This Question Anyway (M1.BC.14.70) The ribosome is an essential organelle that plays an important role in the synthesis of new proteins. The location of the ribosome within the cell can vary and provides a clue to the function of the particular cell. What ribosome location is essential for protein-secreting cells? Review Topic | Tested Concept QID: 106487 Type & Select Correct Answer 1 Rough endoplasmic reticulum 100% (20/20) 2 Smooth endoplasmic reticulum 0% (0/20) 3 Cytosol 0% (0/20) 4 Cell membrane 0% (0/20) 5 Nucleus 0% (0/20) L 1 Question Complexity E Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 1 Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK You have 100% on this question. Just skip this one for now. Take This Question Anyway (M1.BC.13.4) In translation, the wobble phenomenon is best illustrated by the fact that: Review Topic | Tested Concept QID: 100069 Type & Select Correct Answer 1 A tRNA with the UUU anticodon can bind to either AAA or AAG codons 58% (174/300) 2 There are more amino acids than possible codons 13% (39/300) 3 The last nucleotide provides specificity for the given amino acid 16% (49/300) 4 The genetic code is preserved without mutations 7% (21/300) 5 Charged tRNA contains energy needed for peptide bonds to form 3% (10/300) L 1 Question Complexity E Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 1
All Videos (1) Podcasts (0) Login to View Community Videos Login to View Community Videos Differences in translation between prokaryotes and eukaryotes Keshav Mudgal Biochemistry - Protein Synthesis 1/18/2016 66 views (0)