The Structure of DNA

In a DNA strand, the rungs of the "ladder" are made of *

• sugar molecules

• phosphate molecules

• nucleotide bases

• alternating sugar and phosphate molecules

Chargaff's rules are represented as *

• A = T and G = C

• A = G and T = C

• A = C and T = G

• T = C and G = A

Chargaff's rules of base pairing are explained by which structural feature of DNA?

• Each strand of DNA contains a phosphate and sugar backbone.

• The nucleotides of DNA may be arranged in a wide variety of sequences.

• DNA is double stranded, and covalent bonds between identical nucleotides hold the two strands together.

• DNA is double stranded, and hydrogen bonds between base pairs hold the two strands together.

The sequence of nitrogenous bases on a portion of a strand of DNA is shown in the diagram. From left to right, what is the corresponding sequence of the complementary strand?

• CCACTGA

• GGUGTAT

• GGTGACT

• OTTAGATC

Figure 12-5 (the whole thing, not just X) shows the structure of a(an) *

• amino acid

• DNA molecule

• protein

• RNA molecule

In Figure 12.5, the part labeled X is *

• RNA

• a nucleotide

• a phosphate

• a gene

• TA

If 45% of an organism's DNA is thymine, what is the percentage of guanine?

• 5%

• 10%

• 45%

• 90%

Hershey & Chase did an experiment with bacteriophages.  Which term describes a bacteriophage?

• a bacteria that can infect other cells

• Parasite
• A Virus that kills infects bacteria

• a bacteia the infects viruses

Which is a definition of transformation?
*

• a permanent change in gene expression

• a permanent change in the function or activity of a cell

• a temporary change in the genetic composition of an organism

• a permanent change in the genetic composition of an organism

Choose the things that DNA can do that makes it an important biological molecule.

• It can store information.

• It can be copied in a cell.

• It can express a trait by giving directions to a cell.