Q 01/05

Which base does RNA use in place of DNA's thymine?

A) Uracil

B) Guanine

C) Cytosine

D) Inosine

Answer · why

A) Uracil

Uracil. Thymine is just uracil with a methyl group added; because cytosine can decay into uracil, DNA's repair enzymes treat any uracil they find ther...

Q 02/05

Which feature of the ribose sugar chemically distinguishes RNA from DNA?

A) A 5' phosphate

B) A 2' hydroxyl group

C) A methylated 3' carbon

D) A pyranose ring

Answer · why

B) A 2' hydroxyl group

A 2' hydroxyl group. That one extra –OH can attack RNA's own backbone, which is why RNA breaks down so much more easily than DNA, the sturdier long-te...

Q 03/05

Which two bases are the purines RNA shares with DNA?

A) Adenine and guanine

B) Cytosine and thymine

C) Adenine and thymine

D) Guanine and cytosine

Answer · why

A) Adenine and guanine

Adenine and guanine. Purines are built on a double ring and pair only with single-ring partners, which keeps every rung of a double helix the same wid...

Q 04/05

Who discovered nucleic acids in the 1860s and called the material 'nuclein'?

A) Phoebus Levene

B) Friedrich Miescher

C) Albrecht Kossel

D) Erwin Chargaff

Answer · why

B) Friedrich Miescher

Friedrich Miescher. He found it in pus, washing white blood cells off used bandages that a surgical clinic near his Tübingen laboratory sent over.

Q 05/05

Which type of RNA makes up about 80% of the RNA in most cells?

A) Messenger RNA

B) Transfer RNA

C) Small nuclear RNA

D) Ribosomal RNA

Answer · why

D) Ribosomal RNA

Ribosomal RNA. It is never translated into protein itself; cells need it in bulk because it is the main building material of ribosomes, which in bacte...