Updated: 5/2/2017

Chromosomal Structure

Topic
Review Topic
0
0
Questions
1
0
0
Videos
1
Overview
  • Centromere
    • holds sister chromatids together
    • attachment of mitotic spindle fibers
      • allows chromosomes to be pulled to opposite poles during anaphase
    • variations in position
      • metacentric
        • centromere in the middle
      • submetacentric
        • centromere offset slightly towards one end
      • acrocentric
        • near complete displacement of centromere to one end
  • Nomenclature
    • long = q
    • short = p
      • remember: p = petite
    • translocation = t
    • deletion = del
Types of chromosomal alterations
  • Nondisjunction 
    • homologous chromatids do not separate properly during meiosis
      • stage of nondisjunction affects gamete production outcome
        • nondisjunction in meiosis I results in 2 gametes with x 2 and 2 gametes x 0
        • nondisjunction in meiosis II results in 2 normal gametes, 1 gamete x 2 and 1 gamete x 0
      • zygote receiving 3 copies = trisomy
      • zygote receiving 1 copy = monosomy
    • risk greatly ↑ with ↑ in maternal age
      • more common in oogenesis than spermatogenesis
  • Translocation
    • exchange genetic info between nonhomologous chromosomes by breakage and repair
      • balanced
        • where exchanged fragment is still functional on another chromosome
      • unbalanced
        • where exchanged fragment cannot function properly
    • common in cancers
    • types
      • Robertsonian
        • balanced
        • always involve two acrocentric chromosomes
          • 13, 14, 15, 21, 22
        • results in loss of short arm and fusion of two long arms of different chromosomes
        • no clinical presentation because short arms of acrocentrics contain no vital info
          • is a translocation carrier
          • problems with gametogenesis and therefore reproduction
            • miscarriage, aneuploidy
            • depends on how chromosomes segregate during homologous pair separation
      • reciprocal
        • exchange of DNA between two non-homologous chromosomes
          • as long as no DNA is lost the phenotype is normal for that generation
            • is a translocation carrier
  • Inversion
    • type of rearrangement where part of chromosome is inverted in orientation
    • types
      • pericentric
        • inverted chromosomal segment includes centromere
        • remember: pericentric involves centromere
      • paracentric
        • inverted chromosomal segment does not include centromere
  • Ring chromosomes
    • causes
      • product of two breakage sites on the chromosome and the segment lost circularizes
      • ends of chromosomes join circularizing entire chromosome
    • usually lost during gametogenesis → monosomy
  • Isochromosome
    • replication of one arm of a chromosome with loss of the other
      • p-q → p-p'
    • lethal for autosomes
      • can be observed on sex chromosomes
  • Deletions
    • loss of chromosome segment
    • types
      • terminal
        • end of chromosome
      • interstitial
        • within the chromosome
 

Please rate topic.

Average 3.8 of 5 Ratings

Thank you for rating! Please vote below and help us build the most advanced adaptive learning platform in medicine

The complexity of this topic is appropriate for?
How important is this topic for board examinations?
How important is this topic for clinical practice?
Questions (1)
Lab Values
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/L
Female: 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/mL
Female: 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/dL
2-h postprandial:<120 mg/dL
Growth hormone - arginine stimulation Fasting: <5 ng/mL
Provocative 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/mm3
Female: 3.5-5.5 million mm3
Erythrocyte sedimentation rate (Westergren) Male: 0-15 mm/h
Female: 0-20 mm/h
Hematocrit Male: 41%-53%
Female: 36%-46%
Hemoglobin A1c ≤ 6 %
Hemoglobin, blood Male: 13.5-17.5 g/dL
Female: 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/kg
Female: 28-45 mL/kg
Red cell Male: 20-36 mL/kg
Female: 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/min
Female: 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 h
Female: 2.0-8.0 mg/24 h
17-Ketosteroids, total Male: 8-20 mg/24 h
Female: 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

Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK
VIDEOS (1)
Topic COMMENTS (9)
Private Note