Topic 14.

Use the figure to answer the question. Refer to the metabolic pathway illustrated. If I, II, III and IV are all required for growth, a bacterial strain that does not make enzyme Y would be able to grow on medium supplemented with which of the following compounds?

nutrient A and C only

Use the figure to answer the question. Refer to the metabolic pathway illustrated. If I, II, III, and IV are all required for growth, a bacterial strain that does not make enzyme X would be able to grow on medium supplemented with which of the following nutrient(s)?

nutrients A and B only

Use the figure to answer the question. The figure shows a simple metabolic pathway. According to Beadle and Tatum's hypothesis, how many genes are necessary for this pathway?

2

Rank the following mutations with respect to their likelihood of affecting the structure of the polypeptide (from most likely to affect structure to least likely). 1.insertion mutation in the middle of an intron 2.deletion of 3 bases crossing an intron-exon border 3.substitution mutation at the third position of a codon 4.substitution mutation at the second position of a codon

2, 3, 4, 1

Which of the following statements correctly describes a ribozyme?

It is an RNA with catalytic activity.

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.

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

RNA polymerase II

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 codon that specifies the same amino acid as the original codon

3′-UCA-5′

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 statements best supports the one gene-one enzyme hypothesis?

A mutation in a single gene can result in a defective protein.

Which of the following describes the most likely effect that a single base substitution in the middle of gene's sequence will have on the protein the gene encodes?

A single amino acid would change because pairing of mRNA and tRNA in the ribosome would change

Which of the following processes will occur at the exposed 3′ end of a tRNA molecule?

An amino acid will bind covalently.

What is the function of the release factor during translation in eukaryotes?

It binds to the stop codon in the A site in place of a tRNA.

Which of the following statements describes the effect of a nonsense mutation on a gene?

It introduces a premature stop codon into the mRNA.

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 characteristics allows the CRISPR Cas9 enzyme to be an effective way to generate mutations that block the function of a specific protein (knock out)?

It's function is regulated by a complementary guide RNA.

Which of the following properties is associated with a protein that will be secreted from a eukaryotic cell?

Its signal sequence must target it to the ER.

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.

The following question refers to this table of codons. 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

Which answer correctly compares prokaryotic and eukaryotic codons?

Organisms utilize codons that are nearly universal among all organisms.

Which of the following processes occurs as part of transcription?

RNA is synthesized

Which of the following statements about RNA processing is correct?

Ribozymes may function in RNA splicing.

Which of the following is true of RNA processing?

Ribozymes may function in the addition of a 5′5′ cap.

Two mRNAs (mRNA X and mRNA Y) are synthesized with the same exon sequences but poly-A tails of very different lengths. mRNA X is 7,500 bases long. mRNA Y is 6,900 bases long. The mRNA's are added to separate in vitro translation mixtures containing radioactive methionine and the reactions are allowed to proceed for 30 minutes. When the mixtures are analyzed which of the following outcomes will most likely occur?

The mRNA X mixture will contain more radioactive proteins than the mRNA Y mixture.

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 is the most current description of a gene?

a DNA sequence that is expressed to form a functional RNA or polypeptide product

Which of the following statements is true about protein synthesis in prokaryotes?

Translation can begin while transcription is still in progress.

Which of the following changes in an exon is most likely to result in a nonfunctional protein product?

a base-pair deletion

A single base substitution mutation is likely to have a less harmful effect when the base change results in which of the following?

a codon that specifies the same amino acid as the original codon

While characterizing an error-prone organism, researchers found that each of the following types of mutations occurred immediately downstream of the translation start site. Which type of mutation is likely to have the most serious effect on the function of the polypeptide product?

a deletion of two nucleotides

The most commonly occurring mutation in people with cystic fibrosis is a deletion of a single codon. What is the result of this type of mutation?

a polypeptide missing an amino acid

Translation termination occurs when a ribosome interacts with which of the following structures?

a stop codon

Post-translational modifications of proteins may include which of the following processes?

addition of carbohydrates to form a glycoprotein

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

attachment of amino acids to tRNAs

The anticodon of a particular tRNA molecule is ________.

complementary to the corresponding mRNA codon

Jennifer Doudna discovered CRISPR-Cas9 due to its role in which of the following?

defending bacteria against bacteriophage infection

A section of DNA has the base sequence shown in #1. A mutation in this DNA strand results in the base sequence shown in #2. What type of mutation does this change represent? #1 5' - AGCGTTACCGT-3' #2 5'-AGGCGTTACCGT-3'

frameshift mutation

Which of the following is true of a codon?

it can be in either DNA or RNA

Which of the following statements correctly describes the function of a signal peptide?

it helps target a protein to the ER.

Which of the following molecular structures contains codons?

mRNA

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

mRNA

Use the following information to answer the question.An mRNA molecule with the sequence 5′-CCG-ACG-3′is being translated at a ribosome. The following charged transfer RNA molecules (with their anticodons shown in the 3′ to 5′ direction) are available. Two of them can correctly match the mRNA so that a dipeptide can form. tRNA Amino Acid Anticodon --------------------------------------- GGC Proline CGU Alanine UGC Threonine CCG Glycine ACG Cysteine CGG Alanine --------------------------------------- Which of the following dipeptides will form from this mRNA?

proline-threonine

Which component is directly involved in translation?

ribosome

Which answer correctly compares the primary transcript in the nucleus of a eukaryotic cell with the functional mRNA?

the primary transcript is larger than the mRNA

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 eukaryotes which of the following is the first step in translation?

the small subunit of the ribosome recognizes and attaches to the 5′ cap of mRNA

In eukaryotes which of the following is the first step in translation?v

the small subunit of the ribosome recognizes and attaches to the 5′ cap of mRNA

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

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

transcription factors