Molecular Genetics — Flashcards

Flashcard 371: 5α-reductase deficiency = _____

Answer: 46XY

Extra:  https://onlinemeded.org/spa/obgyn?ref=anki 

Flashcard 372: What serum marker is characteristically elevated in choriocarcinoma? _____

Answer: β-hCG

Extra: β-hCG is characteristically elevated in choriocarcinoma, hydatidiform moles, and gestational trophoblastic disease. It is also used to monitor treatment response and screen for recurrence.

Flashcard 373: Chronic myeloproliferative disorders (except CML) are associated with _____ mutations - the mutation is in a gene encoding a(n) tyrosine kinase, which causes tyrosine hyperphosphorylation and hypersensitivity of progenitor cells to cytokines, prolonging cellular growth

Answer: V617F JAK2

Extra:   https://onlinemeded.org/spa/hematology-oncology/leukemia/acquire?ref=anki 

Flashcard 374: HbH and Hgb Barts = _____ thalassemia ↑ HbA2 and ↑ HbF = _____ thalassemia

Answer: alpha

Extra:  https://onlinemeded.org?ref=anki 

Flashcard 375: 5 y/o boy comes with progressive muscle weakness that has resulted in numerous recent falls. - Physical exam: Bilateral calf enlargement. - He uses his hands and arms to help push himself to an upright position. - Genetic analysis reveals a point mutation within exon 48 of the gene encoding this muscle protein. - This patient's gene mutation has most likely resulted in which mRNA codon changes?

Answer: Creation of a premature stop codon (Nonsense mutation) Duchenne Muscular Dystrophy (DMD) is typically caused by frameshift deletions, but when a point mutation is specified, it is most often a nonsense mutation (e.g., UCA → UGA/UAG/UAA).

Flashcard 376: Describe these 2 genetics term? -Transition -Transversion

Answer: Transition: you replaced a purine by a purine, a pyrimidine by a pyrimidine. -Transversion: you replaced a purine by a pyrimidine. A pyrimidine by a purine.

Flashcard 377: An infant appears healthy at birth but develops transfusion-dependent hemolytic anemia by age 6 months. - His erythrocytes contain insoluble aggregates of hemoglobin subunits. - The child developed normally in utero because at that time he produced high quantities of:

Answer: Gamma-globin (γ-globin)

Flashcard 378: In an experiment, a protein mixture obtained from a cell culture is separated by gel electrophoresis and subsequently transferred to a filter membrane. -Labeled: Double-stranded DNA probes are used to detect a specific protein of interest in the sample. -What protein is most likely to be detected by this method? a.) Ras b.) C-Jun c.) B1- adrenoreceptor d.) S-100 e.) Adenylate cyclase

Answer: C-jun Other possible answers: c-Fos, or c-Jun & c-Fos because Double stranded DNA probes were use, which means they are using Southwestern blotting technique, (DNA - binding protein).

Flashcard 379: A group of investigators is studying the mechanisms involved in cancer pathogenesis. -They find that interaction of a certain growth factor with its receptor leads to the following sequence of event: 1. Binding of growth factor 2. Autophosphorylation of tyrosine residues 3. Activation of phosphoinositide 3-kinase 4. Activation of protein kinase B (Akt) 5. Activation of X What is the most likely direct effect of X upon activation?

Answer: Stimulation of protein synthesis The sequence describes the **PI3K/Akt/mTOR** signaling pathway. Step 5 (X) is the activation of **mTOR**. mTOR then phosphorylates targets such as 4E-BP1 and p70S6K to increase mRNA translation. **Note:** mTOR inhibitors like **sirolimus (rapamycin)** are used to treat certain cancers and as immunosuppressants.

Flashcard 380: A 2 y/o boy comes with easy bruising. -Parent stated he develops marked bruising & open wounds following minor trauma. -Skin is difficult to suture due to its extreme fragility. -Physical exam: Hyperextensible skin, multiple ecchymoses over the forearms. - Skin biopsy: defect in extracellular processing of collagen. -Which steps of collagen synthesis is most likely impaired in this patient?

Answer: N-terminal propeptide removal or N & C terminal propeptide removal. due to defect in procollagen peptidases (defect in collagen 3 & 5) that lead to Ehlers-Danlos syndrome. (hyperextensible skin, joint laxity, tissue fragility)