chapter 33

Question 1

what are the four nucleobases in DNA

Answer 1

adenine, cytosine, guanine, thymine

Question 2

what are the four nucleobases in RNA

Answer 2

adenine, cytosine, guanine, uracil

Question 3

which of the bases are purines

Answer 3

adenine, guanine

Question 4

which of the bases are pyrimidines

Answer 4

cytosine, uracil, thymine

Question 5

what is a nucleoside

Answer 5

base + sugar

Question 6

what is a nucleotide

Answer 6

nucleoside + phosphate(s)

Question 7

what is denaturation

Answer 7

disruption of base-pairing

ex: loss of a proton by the base guanine prevents base pairing with cytosine

Question 8

In the interior of the helix, bases are stacked and interact with one another through

Answer 8

van der Waals interactions

Question 9

what moves the nonpolar surfaces of the bases out of water into contact with each other

Answer 9

Base stacking

Question 10

the most common form of DNA in the cell is

Answer 10

B form

Question 11

A-DNA

Answer 11

is shorter and
wider than the B form with
the bases at an angle to
the helix axis

Question 12

Z-DNA

Answer 12

is left-handed
and the backbone is zigzagged, accounting for the name “ZDNA”

commonly believed to provide torsional strain relief
(supercoiling) while DNA transcription occurs

Question 13

stem loop

Answer 13

A common structural motif seen in nucleic acids, most notably RNA, is
the stem-loop, which occurs when complementary sequences in the
same strand form a double helix.

Question 14

central dogma says what

Answer 14

DNA to RNA to proteins