Genetic Code and Codon Usage — Flashcards

Flashcard 1: A _____ mutation occurs when there is a deletion or insertion of a number of nucleotides not divisible by 3, resulting in misreading of all nucleotides downstream.

Answer: frameshift

Flashcard 2: What is the direction of RNA editing?_____

Answer: 3 to 5

Flashcard 3: Okazaki fragments are lagging strands built on RNA primers by DNA polymerase _____.

Answer: DNA polymerase III (prokaryotes) or DNA polymerase δ (eukaryotes)

Extra: In prokaryotes (e.g., E. coli), DNA polymerase III synthesizes both the leading and lagging strands. In eukaryotes, DNA polymerase ε (epsilon) is primarily responsible for leading strand synthesis, while DNA polymerase δ (delta) synthesizes the Okazaki fragments on the lagging strand.

Flashcard 4: Which codons serve as chain terminators in mitochondria?_____

Answer: AGA and AGG

Flashcard 5: At the _____' end of a tRNA molecule is a 5'-CCA-3' sequence, which is the amino acid acceptor stem

Answer: 3

Flashcard 6: _____ DNA is generated by the hydrogen bonding of a third strand into a major groove of B-DNA.

Answer: Triple strand

Flashcard 7: Which codon codes for tryptophan in mitochondria?_____

Answer: UGA

Flashcard 8: Guanosine is converted to _____ via the enzyme purine nucleoside phosphorylase (purine salvage)

Answer: guanine

Flashcard 9: Hypoxanthine is converted to _____ via xanthine oxidase

Answer: xanthine

Flashcard 10: microRNA often leads to the _____ of target mRNA, thus causing decreased translation into protein

Answer: silencing/inactivation