Molecular Genetics Test 40-80

Researchers found a strain of E. coli bacteria that had a mutation rates one hundred times higher than normal. Which of the following statements correctly describes the most likely cause of these results?

• The single-strand binding proteins were malfunctioning during DNA replication

• There were one or more base pair mismatches in the RNA primer

• The proofreading mechanism of DNA polymerase was not working properly

• The DNA polymerase was unable to add bases to the 3' end of the growing nucleic acid chain

In a healthy eukaryotic cell, the rate of DNA repair is typically equal to the rate of DNA mutation. When the rate of repair lags behind the rate of mutation, what is a possible fate of the cell?

• The cell can be transformed into a cancerous cell

• RNA may be used instead of DNA as inheritance material

• DNA replication will proceed more quickly

• DNA replication will continue by a new mechanism

Tags

NGSS.HS-LS3-2

Which of the following statements accurately describes the structure of a eukaryotic chromosome?

• It is composed of a single strand of DNA

• It is constructed as a series of nucleosomes wrapped around two DNA molecules

• It has different numbers of genes in different cell types of an organism

• It is a single linear molecule of double-stranded DNA plus proteins

If a cell were unable to produce histone proteins, which of the following results would be a likely effect on the cell?

• There would be an increase in the amount of DNA produced during replication

• The cell's DNA could not be packed into its nucleus

• Spindle fibers would not form during prophase

• Amplification of other genes would compensate for the lack of histones

Which of the following molecular characteristics cause histones to bind tightly to DNA?

• Histones are positively charged, and DNA is negatively charged

• Histones are negatively charged, and DNA is positively charged

• Both histones and DNA are strongly hydrophobic

• Histones are covalently to the DNA

In DNA replication in E. coli, the enzyme primate is used to attach a 5 to 10 base rib nucleotide strand complementary to the parental DNA strand. The RNA strand serves as a starting point for the DNA polymerase that replicates the DNA. If a mutation occurred in the primase gene, which of the following results would you expect?

• Replication would only occur on the leading strand

• Replication would only occur on the lagging strand

• Replication would not occur on either the leading or lagging strand

• Replication would not be affected as the enzyme primase in involved with RNA synthesis

What is the basis for the difference in how the leading and lagging strands of DNA molecules are synthesized?

• The origins of replication occur only at the 5' end

• Helices and single-strand binding proteins work at the 5' end

• DNA polymerase can join new nucleotides only to the 3' end of a pre-existing strand, and the strands are antiparallel

• DNA ligase works only in the 3' --> 5' direction

A biochemist isolates, purifies, and combines in a test tube a variety of molecules need for DNA replication. When she adds some DNA to the mixture, replication occurs, but each DNA molecule consists of a normal strand paired with numerous segments of DNA a few hundred nucleotides long. What has she probably left out of the mixture.

• DNA polymerase

• DNA ligase

• Okazaki fragments

• Primase

The spontaneous loss of amino groups from adenine in DNA results in hypoxanthine, an uncommon base, opposite thymine. What combination of proteins could repair such damage?

• Nucleus, DNA polymerase, DNA ligase

• Telomerase. Primase, DNA polymerase

• Telomerase, Helicase, Single-strand binding protein

• DNA ligase, Replication fork proteins, Adenylyl cyclase

Which of the following statements correctly describes Archibald Garrod's hypothesis for how "inborn errors of metabolism" such as alkaptonuria occur?

• Metabolic enzymes require vitamin cofactors, and affected individuals have significant nutritional deficiencies

• Enzymes are mad of DNA, and affected individuals lack DNA polymerase

• Certain metabolic reactions are carried out by ribozymes, and affected individuals lack key splicing factors

• Genes dictate the production of specific enzymes, and affected individuals have genetics defects that cause them to lack certain enzymes

Tags

NGSS.HS-LS3-2

NGSS.HS-LS3-1