Bio Chapters 16-20

In E. coli, a mutation in a gene called dnaB prevents the helicase from binding at the originof replication. Which of the following events would you expect to occur as a result of thismutation?

No replication fork will be formed.

A particular triplet of bases in the coding sequence of DNA is 5'-AAA-3'. The anticodon on the tRNA that binds the mRNA codon is ________.

3′-AAA-5′

A particular triplet of bases in the template strand of DNA is 5′-AGT-3′. What would be the corresponding codon for the mRNA that is transcribed?

3′-UCA-5′

A sample of double-stranded DNA contains 42% cytosine. Approximately what percent of thenucleotides in this sample will be thymine?

8%

DNA strands are antiparallel. Which of the following statements defines "antiparallel"?

A 5' to 3' DNA strand is paired with the 3' to 5' DNA strand.

The genetic code is essentially the same for all organisms. From this, one can logically assume which of the following statements to be true?

A gene from an organism can theoretically be expressed by any other organism

Which of the following characteristics allowed Hershey and Chase to determine whether thegenetic material was made of DNA or protein?

DNA contains phosphorus, whereas protein does not.

In bacteria, which of the following proteins is responsible for removing nucleotides from theRNA primer that is used for initiation DNA synthesis?

DNA pol I

What catalyzes the formation of phosphodiester bonds between a DNA strand and a newnucleotide being added during DNA replication?

DNA polymerase

The lagging strand is characterized by a series of short segments of DNA (Okazakifragments) that are joined together to form a finished lagging strand. The experiments that led tothe discovery of Okazaki fragments gave evidence for which of the following ideas?

DNA polymerase synthesizes leading and lagging strands during replication only in onedirection.

After DNA replication, the resulting daughter DNA double helix contains one strand of theoriginal parental DNA and one new strand. What is the explanation for this phenomenon?

DNA replication is semiconservative.

Which of the following investigators was (were) responsible for determining that DNAcontains equal amounts of adenine and thymine, and equal amounts of guanine and cytosine?

Erwin Chargaff

Which of the following statements correctly describes the structure of chromatin?

Heterochromatin is highly condensed, whereas euchromatin is less compact.

Which of the following processes correctly describes alternative RNA splicing?

It can allow the production of proteins of different sizes and functions from a single mRNA.

Which of the following statements correctly describes a ribozyme?

It is an RNA with catalytic activity.

What is the role of DNA ligase in the elongation of the lagging strand during DNAreplication?

It joins Okazaki fragments together.

Who performed classic experiments that supported the semiconservative model of DNA replication?

Meselson and Stahl

Once researchers identified DNA as the molecule responsible for transmitting heritable traits, they asked how information was transferred from the DNA in the nucleus to the site of protein synthesis in the cytoplasm. Which of the following statements correctly describes the mechanism of information transfer that accomplishes this task in eukaryotes?

Messenger RNA is transcribed from a single gene and transfers information to the cytoplasm, where protein synthesis takes place.

Which of the following best describes the redundancy in the genetic code?

More than one codon can specify the addition of the same amino acid

Which answer correctly compares prokaryotic and eukaryotic codons?

Organisms utilize codons that are nearly universal among all organisms.

Which of the following statements accurately describes differences between DNA replicationin prokaryotes and DNA replication in eukaryotes?

Prokaryotic chromosomes have a single origin of replication, whereas eukaryoticchromosomes have many.

In eukaryotes, there are several different types of RNA polymerase. Which type is involved in transcription of mRNA for a protein?

RNA polymerase II

Which of the following statements best describes the termination of transcription in prokaryotes?

RNA polymerase transcribes through the terminator sequence, causing the polymerase to separate from the DNA and release the transcript.

Which of the following statements about RNA processing is correct?

Ribozymes may function in RNA splicing

Telomere shortening puts a limit on the number of times a cell can divide. Research hasshown that telomerase can extend the life span of cultured human cells. Which of the followingbest explains the effect of telomerase on cellular aging?

Telomerase can eliminate telomere shortening and slows aging

Which of the following statements correctly describes the difference between the leadingstrand and the lagging strand in DNA replication?

The leading strand is synthesized continuously in the 5'→ 3' direction, while the laggingstrand is synthesized discontinuously in the 5'→ 3' direction.

Which of the following is most likely to occur if a researcher removes the 5′ cap and poly-A tail of an mRNA and inserts the mRNA molecule into a eukaryotic cell?

The molecule will be degraded by enzymes.

Which of the following statements correctly describes the difference between ATP used inmetabolism and the nucleotides used as a building block during DNA synthesis?

The nucleotides have the sugar deoxyribose; ATP has the sugar ribose.

Researchers found a strain of bacteria that had mutation rates one hundred times higher thannormal. Which of the following statements correctly describes the most likely cause of theseresults?

The proofreading mechanism of DNA polymerase was not working properly.

Which of the following best explains the observation that in bacteria, there are 61 mRNA codons that specify an amino acid, but only 45 tRNAs?

The rules for base pairing between the third base of a codon and tRNA are flexible

Frederick Griffith heat-killed a culture of pathogenic bacteria. He split the sample and injectedhalf of it into mice. The mice lived. He then mixed the other half with a living, nonpathogenicbacteria strain and injected the mixture into mice. The mice died. These results best supportwhich of the following conclusions.

a substance had been transferred from pathogenic to nonpathogenic bacteria

Rosalind Franklin's X-ray crystallography data suggested DNA is double stranded and has auniform diameter. These observations can be used to rule out base pairing between two of thesame nucleotide because ________.

an A-A pair is wider than a C-C pair

Accuracy in translation of mRNA into the primary structure of a polypeptide depends on specificity in the ________.

attachment of amino acids to tRNAs

What are telomeres?

he ends of linear chromosomes

According to the central dogma, which of the following intermediate molecules correctly completes the flow chart describing the flow of information in a cell blank? DNA → ________ → Proteins

mRNA

Which of the following lists represents the order of increasingly higher levels of organization of chromatin?

nucleosome, 30-nm chromatin fiber, looped domain

What is the function of the enzyme topoisomerase in DNA replication?

relieving strain in the DNA ahead of the replication fork caused by the untwisting of thedouble helix

Which of the following characteristics of DNA allows it to carry a vast amount of hereditary information?

sequence of bases

Which of the following types of molecules help to hold the DNA strands apart while they arebeing replicated?

single-strand DNA binding proteins

Which of the following statements best describes the significance of the TATA box in the promoters of eukaryotes?

t is the recognition site for the binding of a specific transcription factor.

In DNA polymerization, a phosphodiester bond is formed between a phosphate group of thenucleotide being added and which of the following atoms or molecules of the last nucleotide inthe polymer?

the 3' OH

Which answer correctly compares the primary transcript in a prokaryotic cell with the functional mRNA?

the primary transcript is the same size as the mRNA

In the structure of many eukaryotic genes, individual exons parallel which of the following?

the various domains of the protein product

In bacteria, what is the function of DNA polymerase III?

to add nucleotides to the 3' end of a growing DNA strand

Transcription in eukaryotes requires which of the following molecules in addition to RNA polymerase?

transcription factors