Nucleic Acid Biochemistry — Flashcards

Flashcard 21: When the _____ domain is removed from DNA polymerase I, the remaining fragment is called as Klenow fragment.

Answer: 5' 3' exonuclease

Flashcard 22: Orotic acid is combined with _____ to form UMP (pyrimidine synthesis)

Answer: phosphoribosyl pyrophosphate (PRPP)

Extra: This process is catalyzed by the bifunctional enzyme **UMP synthase**, which possesses both orotate phosphoribosyltransferase and OMP decarboxylase activities. Orotidine 5'-monophosphate (OMP) is the immediate intermediate formed before decarboxylation to UMP.

Flashcard 23: In the first step of pyrimidine synthesis, glutamine and CO2 are combined to form _____ via the enzyme carbamoyl phosphate synthetase II (requires 2 ATP)

Answer: carbamoyl phosphate

Flashcard 24: Conversion of dUMP to dTMP via Thymidylate synthase converts the cofactor _____ to DHF

Answer: methylene THF

Flashcard 25: Ribose-5-phosphate is converted to _____ via the enzyme PRPP synthetase

Answer: phosphoribosyl pyrophosphate (PRPP)

Flashcard 26: In the RISC complex, miRNAs can modulate mRNA function by stimulating _____ degradation or inhibiting translation by targeting eIF4 translation factor, in case of imperfect complementarity.

Answer: poly(A) tail

Flashcard 27: In the first step of alternative splicing, the primary transcript (hnRNA) combines with _____ and other proteins to form the spliceosome

Answer: small nuclear ribonucleoproteins (snRNPS)

Flashcard 28: RNA polymerase _____ makes tRNA and 5S rRNA

Answer: III

Flashcard 29: Primary miRNA is converted to _____ intranuclearly by the enzyme complex DROSHA

Answer: pre-miRNA

Flashcard 30: _____ DNA is generated by the hydrogen bonding of a third strand into a major groove of B-DNA.

Answer: Triple strand