DNA Structure

Cytosine makes up 38% of the nucleotides in a sample of DNA from an organism. Approximately what percentage will thymine take up?

12%

In analyzing the number of different bases in a DNA sample, which result would be consistent with the base-pairing rules?

A+G=C+T

Suppose you are provided with an actively dividing culture of E. coli bacteria to which radioactive thymine has been added. What would happen if a cell replicates once in the presence of this radioactive base?

DNA in both daughter cells would be radioactive

I'm a bulky base that clings extra tightly to my more petite partner on the opposite side of the double helix. Who am I?

Guanine

E. coli cells grown on 15N medium are transferred to 14N medium and allowed to grow for two more generations (two rounds of DNA replication). DNA extracted from these cells is centrifuged. What density distribution of DNA would you expect in this experiment?

One low-density and intermediate-density band

In a double helix, the nucleotides within the same strand are held together by _____, while each nucleotide also interacts with a nucleotide in the other strand by ______.

Phosphodiester linkages, hydrogen bonds

Why does the DNA double helix have a uniform diameter

Purines pair with pyrimidines

Once the pattern found after one round of replication was observed, Meselson and Stahl could be confident of which of the following conclusions?

Replication is not conservative

What is meant by the description "antiparallel" reagarding the strands that make up DNA?

The 5' to 3' direction of one strand runs counter to the 3' to 5' direction of the other strand

Chargaff's analysis of the relative base composition of DNA was significant because he was able to show that

The amount of A equals T and the amount of C equals G