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 391: What are the followilngs are associated with in relation to tRNA?
-CCA
-Poly-A
-Methylguanosine-triphosphate
-TATA
Answer: CCA: locates in the 3' end of tRNA molecule
-Poly-A: occurs after transcription, it will bind to the 3' cap.
-Methylguanosine: It will bind to the 5' cap of mRNA after transcription.
-TATA: an upstream promoter. helpful in transcription. TATA binding proteins will bind there during transcription.
Flashcard 392: 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.
Flashcard 393: In a research, they isolate small circular DNA that resemble a bacterial chromosome from exocrine panreatic cells..
-Further analysis shows that these molecules code for proteins, transfer RNA, & ribosomal RNA.
-From which of the following cellular structures did these DNA molecules most likely originate?
Answer: D.) Mitochondria
Key: Mitochondria contains circular DNA chromosomes that resembles bacterial (prokaryotic) chromosomes. Inherited from Mother.
Mutation in mitochondrial DNA could cause disease to pass from mother to offsprings.
A.) Rough Endoplasmic reticulum: contains multiple ribosomes to synthesize proteins.
B.) Nucleolus: site of synthesis of ribosomal components.
C.) Nucleus: contains euchromatin (chromosomes) inside of it.
E.) Exocrine granules: usually contains enzymes and other proteins package for secretion.
Flashcard 394: 24 y/o woman is diagnosed with gestational diabetes mellitus during her 1st pregnancy.
-Mother & younger sister had high blood surgars during pregnancy.
-If this patient's gestational hyperglycemia is genetically predisposed, she is most likely to have decreased activity in what enzyme?
Answer: Glucokinase
Glucokinase need to phosphorylate glucose to breakdown in glycolysis in order to release ATP to close down the K channel, which lead to influx of Ca that causes release of insulin.
due to Maturity Onset Diabetes of the Young (MODY)
(hereditary mutation of glucokinase gene)
Key: Her mother & her younger sister had diabetes too during their pregnancy, very young.
Flashcard 395: What types of nuclease activity will present in the following enzymes?
-DNA polymerase 1
-DNA polymerase 3
Answer: DNA polymerase 1: 5' to 3' exonuclease activity
DNA polymerase 3: 3' to 5' exonuclease activity
Flashcard 396: In an experiment, individual bacterial colonies lack a specific enzyme involed in DNA replication.
-This specific enzyme is responsible for removing short fragments of RNA that are base paired to the DNA template.
-Which enzymes is most likely deficient in this strain of E. coli?
Answer: DNA polymerase 1.
because it removes primers & replaced them with DNA nucleotides.
** Key: Don't confuse with Primers. Primers add DNA nucleotide while DNA polymerase 1 removes primers.
Flashcard 397: What are the followings associated with?
-Cleavage of DNA strands to remove supercoils
-Excision of thymine dimers within DNA
-Removal of mismatched base pairs during DNA replication
-Removal of RNA primer nucleotides
-Unwinding of the 2 strands of template DNA
(DNA polymerase 1, DNA gyrase, UV-specific endonuclease, helicase)
Answer: Cleavage of DNA strands to remove supercoils: DNA gyrase (topoisomerase 2)
-Excision of thymine dimers within DNA: UV-specific endonuclease.
-Removal of mismatched base pairs during DNA replication: DNA polymerase 3 (most common), DNA pol 1, DNA pol 2.
-Removal of RNA primer nucleotides: DNA polymerase 1
-Unwinding of the 2 strands of template DNA: Helicase
Flashcard 398: A researcher develops 2 functional mRNA sequences composed of CUC & CUU trinucleotide repeats.
-He subsequntly incubates them.
-After a few hours, it is found that both mRNA sequences produce polypeptide chains containing leucine repeats.
-This observed finding is due to what genetic principles?
Answer: Wobble
(wobble hypothesis: which stated that if you have 3 base pairing, 2 of them could match while you could wobble the 3rd one, which means the 3rd one could be a mismatch).
Flashcard 399: What are the two types of DNA mutation that occurs in duchenne muscular dystrophy?
Answer: Frameshift, nonsense mutation.
Flashcard 400: 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
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