DNA Test Review

Which of the following events occurs directly after a DNA molecule is unzipped?

• Mismatched nucleotide bases are identified and replaced.

• Identical double-stranded DNA molecules are formed.

• Free-floating nucleotides pair up with exposed bases.

• Enzymes break hydrogen bonds between base pairs.

The attachment of nucleotides to form a complementary strand of DNA during replication is accomplished by DNA polymerase.

• is accomplished only in the presence of tRNA.

• is the responsibility of the proofreading molecules.

• prevents separation of complementary strands of RNA.

What holds base pairs together?

• hydrogen bonds

• pairs of double-ringed nucleotides

• sugar-phosphate backbones

• nitrogen-carbon bonds

After examining the DNA of different organisms, which of the following did Erwin Chargaff conclude about the four bases?

• A = T and C = G

• A = C and G = T

• A = C = G = T

• A + T = C + G

The amount of guanine in an organism always equals the amount of

• cytosine.

• adenine.

• protein.

• thymine.

Tags

NGSS.HS-LS3-1

The enzymes responsible for adding nucleotides to the exposed DNA bases as well as proofreading during replication are

• replicases.

• helicases.

• DNA polymerases.

• template enzymes.

The process of making new DNA molecules is semiconservative. This means that every new DNA molecule is composed of

• two completely identical strands of DNA.

• one strand of DNA and one strand of RNA.

• one original and one new strand of DNA.

• one strand that mixes original and new DNA.

When new DNA molecules are formed, almost all errors are detected and fixed by

• the correct nucleotide.

• DNA polymerase.

• the sugar-phosphate backbone.

• one DNA strand.

Molecules of DNA are composed of long chains of

• amino acids.

• monosaccharides.

• fatty acids.

• nucleotides.

A nucleotide consists of

• a sugar, an amino acid, and starch.

• a starch, a phosphate group, and a nitrogen base.

• a sugar, a protein, and adenine.

• a sugar, a phosphate group, and a nitrogen base.