Mastering Biology: Chapter 17

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

several transcription factors

In the structural organization of many eukaryotic genes, individual exons may be related to which of the following?

the various domains of the polypeptide product

A codon consists of _____ bases and specifies which _____ will be inserted into the polypeptide chain.

three ... amino acid

Drag the correct label to each target in the table. Labels may be used more than once.

1. yes, no 2. no, yes 3. yes, yes 4. yes, no

Which of the following sequences of nucleotides are possible in the template strand of DNA that would code for the polypeptide sequence Phe-Leu-Ile-Val?

3-AAA-GAA-TAA-CAA-5

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

3-GGC-5

Which components of the previous molecule will also be found in mRNA in the cytosol?

5' UTR E1 E2 E3 E4 UTR 3'

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 supports the one gene-one enzyme hypothesis?

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

Which of the following molecules is/are produced by translation? Include molecules that are subject to further modification after initial synthesis.

Aminoacyl-tRNA synthetase RNA polymerase

Which of the following mutations would likely be most dangerous to a cell?

Deletion of one nucleotide

Where does RNA polymerase begin transcribing a gene into mRNA?

It starts after a certain nucleotide sequence called a promoter.

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 template strand of a gene contains this sequence: 3'-TAC TAG GCT AGT TGA-5'. A mutation occurs that changes the gene sequence to 3'-TAC TAG ACT AGT TGA-5'. How does this mutation affect the resulting amino acid sequence?

The mutation introduces a stop codon.

Generally speaking, which of the following mutations would most severely affect the protein coded for by a gene?

a frameshift deletion at the beginning of the gene

Which domain of the insulin precursor protein is affected by each of the four SNPs? Terms may be used once, more than once, or not at all.

1. B chain 2. C peptide 3. dibasic chain 4. A chain

Based on the competition assay results, how would you characterize the insulin produced by patient 1? Drag a blue label to the blue target and a pink label to the pink target to complete the sentences.

1. Lower 2. Diabetic

Which of the following anticodons in the first tRNA to bind will complement this mRNA?

3-GGC-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

Which of the following statements correctly describes the effect a nonsense mutation would have 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.

What is the function of RNA polymerase?

It unwinds the double helix and adds nucleotides to a growing strand of RNA.

The genetic code is redundant. What is meant by this statement?

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

The average length of a transcription unit along a eukaryotic DNA molecule is about 27,000 nucleotide pairs, whereas an averaged-sized protein is about 400 amino acids long. What is the best explanation for this fact?

Most eukaryotic genes and their RNA transcripts have long noncoding stretches of nucleotides that are not translated.

Using the results of your BLAST alignments, complete the table below by dragging one blue label to each blue target and one pink label to each pink target. Labels may be used once, more than once, or not at all. Answers for the example alignment presented above are included in the first row of the table as a guide.

Patient 1: 125 - T - G Patient 2: 220 - G - A

Drag blue labels to blue targets and pink labels to pink targets. Labels may be used once, more than once, or not at all. For help getting started, open the Hints.

Patient 1: A + B Patient 2: A + B - normal Patient 3: A + B + C - diabetic Patient 4: diabetic

For each patient, use the information above to indentify the wild-type amino acid at each SNP location, then use the codon table to determine the new amino acid at the SNP location, and finally determine the type of mutation caused by each SNP. For help getting started, open the Hints.

Patient 1: Val - Gly - missense Patient 2: Ala - Thr - missense Patient 3: Arg - Pro - missense Patient 4: Tyr - stop - nonsense

Using these additional alignments, complete the table you started in Part A.

Patient 3: 164 - G - C Patient 4: 309 - C - G

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

RNA polymerase II

Which one of the following statements about RNA processing is correct?

Ribozymes may function in RNA splicing.

In bacteria, there are 61 mRNA codons that specify an amino acid, but only 45 tRNAs. Which of the following statements explains this fact?

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

Which of the following DNA mutations is most likely to damage the protein it specifies?

a base-pair deletion

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

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

Which of the following types of mutation, resulting in an error in the mRNA just after the AUG start of translation, is likely to have the most serious effect on 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

In this activity, you will examine two specific nucleotide-pair deletion mutations that affect this region of the CFTR sequence: [delta]F508 and 1660delG. Drag the amino acids to the white targets to indicate what each mRNA codon codes for. (You will probably need to consult the codon table for mRNA.) Drag the blue labels to the blue targets to indicate the effect on the polypeptide's primary structure. Be sure to compare the mutant amino acid sequence to the wild-type sequence above. Labels may be used once, more than once, or not at all.

a: Ile b: Gly c: Val d: ser e: Phe f: Pro g: no frameshift h: frameshift-extensive missense

In this activity, you will examine three different mutations. Drag the white labels to the white targets to indicate what each mutant mRNA codon codes for. (You will probably need to consult the codon table for mRNA .) Drag the pink labels to the pink targets to indicate the type of mutation. Drag the blue labels to the blue targets to indicate the effect on the polypeptide's primary structure. Labels may be used once, more than once, or not at all.

a: Val b: substitution c: missense d: Glu e: substitution f: silent g: stop h: substitution i: nonsense

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

addition of carbohydrates to form a glycoprotein

Refer to the metabolic pathway illustrated. If A, B, and C are all required for growth, a strain that is mutant for the gene-encoding enzyme A would be able to grow on medium supplemented with which of the following nutrient(s)?

either nutrient B or C

An original section of DNA has the base sequence AGCGTTACCGT. A mutation in this DNA strand results in the base sequence AGGCGTTACCGT. What type of mutation does this change represent?

frameshift mutation

If a segment of DNA were replicated without any errors, the replicated strand would have the following sequence of nucleotides: 5' - ACTACGTGA - 3' Sort the following replicated DNA sequences by the type of point mutation each contains (frameshift, base substitution, or neither), as compared to the correct sequence shown above. Sort the items into the appropriate bins.

frameshift mutation: 5'-ACTCGTGA-3' 5'-ACTTACGTGA-3' base substitution mutation 5'-ACTAAGTGA-3' 5'-ACTACGTGT-3' *None are neither*

Drag each label into the appropriate bin depending on whether it applies to primary, secondary, tertiary, or quaternary structure.

primary structure: amino acid sequence secondary structure: results from hydrogen bonding between the backbone constituens of the polypeptide β pleated sheet α helix tertiary structure: the overall shape of a polypeptide results from interactions between side chains(R groups) of amino acids quaternary structure: the aggregation of multiple polypeptide subunits

Which of the following dipeptides will form from this mRNA?

proline-threonine