BIO EXAM 2

Which of the following conditions is most likely to result in transcription of lac operon?

The cAMP and lactose levels are both high within the cell.

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

single-strand DNA binding proteins

Which of the following combinations of base pairs will be found in a molecule of DNA?

A + C = G + T

A sample of double-stranded DNA contains 28% thymine. Approximately what percent of the nucleotides in this sample will be guanine?

22%

Which of the following functions are characteristic of general transcription factors in eukaryotes?

They bind to other proteins or to the TATA box.

The anticodon of a particular tRNA molecule is

complementary to the corresponding mRNA codon.

Refer to the table. Which of the triplets below is a possible anticodon in a tRNA that transports proline to a ribosome?

3’-GGC-5’

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

the 3’ OH

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

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

Which of the following statements correctly describes the difference between the leading and the lagging strands of DNA in DNA replication?

The leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction.

Which of the following processes occurs as part of transcription?

RNA is synthesized

Which of the following is an example of post-transcriptional control of gene expression?

the removal of introns and alternative splicing of exons

Which of the following results is most likely to occur if acetylation of histone tails in the chromatin of embryonix cells is increased?

decreased chromatin condensation

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

Erwin Chargaff

Identify a 5’ → 3’ sequence of nucleotides in the DNA template strand for an mRNA coding for the polypeptide sequence Phe-Pro-Lys.

5’ - CTTCGGGAA - 3’

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’

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

a substance had been transferred from pathogenic to nonpathogenic bacteria

Muscle cells differ from nerve cells mainly because they

express different genes

According to the lac operon model proposed by Jacob and Monod, what is predicted to occur if the operator is removed from the operon?

The lac operon would be transcribed continously

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

8%

What amino acid sequence will be generated based on the following mRNA codon sequence? 5’-AUG-UCU-UCG-UUA-UCC-UUG-3’

Met-Ser-Ser-Leu-Ser-Leu

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 another organism.

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 the double helix

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

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

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

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

For a repressible operon to be transcribed, which of the following conditions must occur?

RNA polymerase must bind to the promoter, and the repressor must be inactive.

Which component is directly involved in translation?

ribosome

Hershey and Chase set out to determine which type of molecule is used for genetic inheritance. They completed a series of experiments where E. coli was infected by a T2 virus. Which molecular component of the T2 virus ended up inside the cell?

DNA

Which of the following molecular structures contains codons?

mRNA

In analyzing the number of different bases in a DNA sample, which result would be consiten with the base-pairing rule.

A + G = C + T

The functioning of enhancers is an example of

transcriptional control of gene expression

Which of the following best explains why a neuron and a pancreatic cell isolated from the same individual contain different sets of proteins?

Each cell type contains different regulatory proteins, and therefore, the express different proteins.

If a mutation deactivated a regulatory gene of repressible operon in an E. coli cell which of the following describes the most likely outcome?

continous transcription of the structural gene controlled by that regulator

The elongation of the leading strand during DNA synthesis

depends on the action of DNA polymerase

Which of the following characteristics is directly related to the coding of a single amino acid during the process of translation?

the three-base sequence of mRNA

Which of the following statements correctly describes, the primary difference between enhancers and proximal control elements?

Enhancers are located considerable distances from the promoter; proximal control elements are close to the promoter.

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

sequence of bases

Which of the following molecules binds with a repressor to alter its conformation and therefore affect its function?

inducer

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

transcription factors

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

It joins Okazaki fragments together.

According to the central dogma, which of the following intermediated molecules correctly completes the flow chart describing the flow of information in a cell blank?
DNA - ______ - Proteins

mRNA

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.

What would occur if the repressor of an inducible operon were mutated so it could not bind the operator?

continuous transcription of the operon’s genes

Which of the following statements describes the process of transformation in bacteria?

External DNA is taken into a cell, becoming part of the cell’s genome.

In his work with pneumonia-causing bacteria and mice, Griffith found that

some subtance from pathogenic cells was transferred to nonpathogenic cells, makng them pathogenic

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

DNA contains phosphorus, whereas protein does not.

Which of the following molecules carries information from DNA and directs incorporation of amino acids at the ribosome?

mRNA