Molecular Genetics — Flashcards

Flashcard 61: "frameshift" with respect to a DNA point mutation

Answer: mutation offsets reading frame

Flashcard 62: "nonsense" with respect to a DNA point mutation

Answer: new codon corresponds to stop sequence

Flashcard 63: "missense" with respect to a DNA point mutation

Answer: Result in a codon that codes for a different amino acid.

Extra: Conservative missense: New amino acid is chemically similar to the original. Non-conservative missense: New amino acid is chemically different (e.g., Sickle Cell Anemia: Glutamic acid [polar] replaced by Valine [non-polar]).

Flashcard 64: "silent" with respect to a DNA point mutation

Answer: new codon corresponds to same amino acid

Flashcard 65: Give one exception to the universal nature of the genetic code.

Answer: mitochondria

Flashcard 66: Give one exception to the nonoverlapping nature of the genetic code.

Answer: some viruses

Flashcard 67: Give two exceptions to the redundancy in the genetic code.

Answer: methionine, tryptophan

Flashcard 68: "universal" with reference to the genetic code

Answer: conserved throughout evolution

Flashcard 69: "nonoverlapping" with reference to the genetic code

Answer: reads from a fixed point as a continuous sequence of bases

Flashcard 70: Identify the purine base that has a carbonyl group at C-6 and an amino group at C-2:

Answer: Guanine

Extra: Guanine (2-amino-6-oxopurine) pairs with Cytosine via three hydrogen bonds. Purines with oxygen: Guanine (1 oxygen); Purines without oxygen: Adenine.