Molecular Genetics US Medical PG Flashcards - Medical Study Cards
Master Molecular Genetics with OnCourse flashcards. These spaced repetition flashcards are designed for medical students preparing for NEET PG, USMLE Step 1, USMLE Step 2, MBBS exams, and other medical licensing examinations.
Molecular Genetics Flashcard Deck - 10 Cards
Flashcard 381: What are the followins in relations to both eukaryotic and prokaryotic DNA?
-Continuous synthesis of the lagging strand
-Energy-independent DNA unwinding
-Multiple origins of replication
-No proofreading of daughter strands
-No requirement for RNA primers
Answer: Continuous synthesis of the lagging strand: lagging strand is not continuous in both prokaryotic and eukaryotic DNA.
-Energy-independent DNA unwinding: They both need energy to unwind DNA by helicase.
-Multiple origins of replication: Eukaryotic DNA, to make it effective and fast.
-No proofreading of daughter strands: Both need proofreading.
-No requirement for RNA primers: They both need a primer in order to begin replication by a primase.
Flashcard 382: An infant born appears healthy at birth but develops transfusion-dependent hymolytic anemia by age of 6 months.
-His erythrocytes contain insoluble aggregated of hemoglobin subunits.
-The child developed normally in utero because at that time he produced high quantities of:
Answer: Y-globin
Flashcard 383: HBC disease is caused by a single amino acid substitution (glutamic acid ---> lysine) at position 6 in B-globin chain of Hb molecule.
-Patient homozygous for HBC have mild chronic hemolytic anemia.
-Those with HbS generally have a more severe condition.
-Which properties of HbS best explains why HbS disease is associated with more pronouced clinical manifestations than HbC disease?
Answer: HbS allows hydrophobic interaction among hemoglobin molecules.
because of the Glu (-) polar ---> Lysine (no charge) (nonpolar), normally HB tetramer has polirity outside of their surface while nonpolarity hide inside.
Since the change of one amino acid will expose nonpolar outside lead to partial destruction of those RBC cells and causes lack of oxygen in the body.
Compare to HBC which change from polar (-) Glutamate to another polar (+) Lysine, thus don't present with severe conditions.
Flashcard 384: What kind of mutation exits in the following bases?
- CUU (leucine) ---> AUU (Isoleucine)
- UUU (Phynylalanine) ---> UUC (Phenylalanine)
- CAG, CCC, ACT ---> CAG, TCC, CAC,T
- CAG, CAG, UAA ---> CAG, CAG, CAA
-UCA ----> UGA
(Silent, missense, nonsense, nonstop, framshift)
Answer: CUU (leucine) ---> AUU (Isoleucine): missense mutation
- UUU (Phynylalanine) ---> UUC (Phenylalanine): Silent mutation
- CAG, CCC, ACT ---> CAG, TCC, CAC,T: Frameshift mutation
- CAG, CAG, UAA ---> CAG, CAG, CAA: Nonstop mutation
- UCA ----> UGA: Nonsense mutation
Flashcard 385: The following Hemoglobin are associted with:
-Hemoglobin C
-Hemoglobin F
-Hemoglobin H
-Hemoglobin S
Answer: Hemoglobin C: (HbC), mutation that cause glutamate to be replaced by Lysine, leads to hemolytic anemia.
-HbF: Hemoglobin Fetus, has high affinity to oxygen
-HbH: Alpha thalassemia,(Hb Barts) with complete absent of Alpha globin, have really high affinity to oxygen, resembles myoglobin.
-HbS: Sickle cell anemia, replacement of glutamate by valine
Flashcard 386: What are the following markers?
-Ras
-c-Jun
-B1 - adrenoreceptor
-S- 100
-Adenylate cyclase
-C-fos
Answer: Ras: Protooncogene activates MAP kinase pathway, affect transcription, has GTPase gene product. (associated with colon, pancreatic, and lung cancer.)
-c-Jun: The protein that binds to DNA in southwestern blot (double stranded DNA probe).
-B1-adrenoreceptor: Gs protein couple receptor.
-Adenylate cyclase: cleaves ATP to form cAMP.
-S-100: calcium binding proteins.
-c-Fos: Proteins that bind to DNA to form double stranded DNA probe in Southwestern blot.
Flashcard 387: 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)
Flashcard 388: 6 y/o African American boy comes in by his parents due to easy fatigability.
-Physical exam: splenomegaly, CBC: mild anemia.
-Hemoglobin electrophoresis for the patient are shown below compared to individuals with normal hemoglobin and know sickle cell disease.
What mutation is most likely cause of this patient's condition?
Answer: Missense mutation
due to HbC hemolytic anemia
Speed on gel electrophoresis: A,S,C
HbA: normal
HbS: sickle cell anemia
HbC: Mild hemolytic anemia.
Flashcard 389: True or False in relation to sickle cell anemia?
a.) HbS decreases Beta -globin interaction with 2,3-diphosphoglycerate
b.) HbS impairs oxygen binding to the heme moiety
c.) HbS allows hydrophobic interaction among hemoglobin molecules.
Answer: a.) & b.) False, otherwise HbS will have a higher affinity for oxygen or higher affinity for 2,3 BPG. HbS causes partial destruction of the hememolecules that prevent from carry lots of oxygen.
c.) True, due to Glu (-) (polar) ---> Val (No charge) (non polar)
Flashcard 390: What are the speed of the followings in gel eletrophoresis in relation to normal hemoglobin (HbA)?
-Framshift mutation
-Missense mutation
-Nonsense mutation
-Silent mutation
-Trinucleotide expansion
Answer: Frameshift mutation: involves in Alpha thalassema (Duchenne M. D.). Will contain HbH that will move faster than HbA.
-Missense mutation: Most likely occurs in HbC anemia or sickle cell anemia (due to change of amino acids). will occurs slower than HbS, & HbA.
-Nonsense mutation: Will create smaller protein due to early stop on translation (duchenne M. D.). They will tend to move faster.
-Silent mutation: will not affect protein since they will code for the same amino acid
-Trinucleotide expansions: will result in a large proteins, they will move slower than HbA.
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