AP Bio Chapter 17 Test

c

A primary transcript in the nucleus of a eukaryotic cell is _____ the functional mRNA, while a primary transcript in a prokaryotic cell is _____ the functional mRNA. A) the same size as; larger than B) the same size as; smaller than C) larger than; the same size as D) larger than; smaller than

d

Accuracy in the translation of mRNA into the primary structure of a polypeptide depends on specificity in the A) binding of the anticodon to small subunit of the ribosome B) attachment of amino acids to tRNAs. C) binding of ribosomes to mRNA. D) binding of the anticodon to the codon and the attachment of amino acids to tRNAs.

a

Alternative RNA splicing _____. A) can allow the production of proteins of different sizes and functions from a single mRNA B) increases the rate of transcription C) is a mechanism for increasing the rate of translation D) can allow the production of similar proteins from different RNAs

d

Codons are three-base sequences that specify the addition of a single amino acid. How do eukaryotic codons and prokaryotic codons compare? A) Prokaryotic codons usually specify different amino acids than those of eukaryotes. B) The translation of codons is mediated by tRNAs in eukaryotes, but translation requires no intermediate molecules such as tRNAs in prokaryotes. C) Prokaryotic codons usually contain different bases than those of eukaryotes. D) Codons are a nearly universal language among all organisms.

a

In an experimental situation, a student researcher inserts an mRNA molecule into a eukaryotic cell after he has removed its 5' cap and poly(A) tail. Which of the following would you expect him to find? A) The molecule is digested by exonucleases since it is no longer protected at the 5' end. B) The mRNA attaches to a ribosome and is translated, but more slowly C) The mRNA is quickly converted into a ribosomal subunit D) The cell adds a new poly-A tail to the mRNA

c

The figure above shows a simple metabolic pathway. According to Beadle and Tatum's hypothesis, how many genes are necessary for this pathway? A) 3 B) 1 C) 2 D) It cannot be determined from the pathway.

d

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? A. the mutation changes a single amino acid to another amino acid B. the mutation does not affect the amino acid sequence C. the mutation eliminates the stop codon in the third triplet D. the mutation introduces a stop codon

a

What amino acid sequence will be generated, based on the following mRNA codon sequence? 5' AUG-UCU-UCG-UUA-UCC-UUG 3' A) met-ser-ser-leu-ser-leu B) met-arg-glu-arg-glu-arg C) met-glu-arg-arg-glu-leu D) met-ser-leu-ser-leu-ser

a

A--enzyme A-->B--enzyme B-->C Refer to the metabolic pathway illustrated above. 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 _____. A) nutrient B only B) nutrient A only C) nutrient C only D) nutrients A and C

d

How might a single base substitution in the sequence of a gene affect the amino acid sequence of a protein encoded by the gene and why? A. the amino acid sequence would be substantially altered, because the reading frame would change with a single base substitution. B. all amino acids following the substitution would be affected, because the reading frame would be shifted. C. it is not possible for a single base substitution to affect protein strcutre, because each codon is three bases long. D. only a single amino acid could change, because the reading frame is unaffected

d

Once researchers identified DNA as the unit of inheritance, they asked how information was transferred from the DNA in the nucleus to the site of protein synthesis in the cytoplasm. What is the mechanism of information transfer in eukarotes? a. protein transfer information from the nucleus to the ribosome, where protein synthesis takes place. b. DNA from a single gene is replicated and transferred to the cytoplasm, where it serves as a template for protein synthesis c. transfer RNA takes information from DNA directly to a ribosome, where protein synthesis takes place d. messenger RNA is transcribed from a single gene and transfers information from the DNA in the nucleus to the cytoplasm, where protein synthesis takes place.

d

The genetic code is essentially the same for all organisms. From this, one can logically assume all of the following except A) a gene from an organism could theoretically be expressed by any other organism. B) the same codons in different organisms usually translate into the same amino acids. C) different organisms have the same number of different types of amino acids. D) DNA was the first genetic material.

c

There are 61 mRNA codons that specify an amino acid, but only 45 tRNAs. This is best explained by the fact that A) many codons are never used, so the tRNAs that recognize them are dispensable. B) the DNA codes for all 61 tRNAs but some are then destroyed. C) the rules for base pairing between the third base of a codon and tRNA are flexible. D) some tRNAs have anticodons that recognize four or more different codons.

a

What does it mean when we say the genetic code is redundant? A. More than one codon can specify the addition of the same amino acid. B. The genetic code is different for different domains of organisms. C. A single codon can specify the addition of more than one amino acid. D. The genetic code is universal (the same for all organisms).

d

What type of bonding is responsible for maintaining the shape of the tRNA molecule? A) peptide bonding between amino acids B) ionic bonding between phosphates C) van der Waals interactions between hydrogen atoms D) hydrogen bonding between base pairs

d

Which of the following contradicts the one-gene, one-enzyme hypothesis? A) A mutation in a single gene can result in a defective protein. B) Sickle-cell anemia results in defective hemoglobin. C) Alkaptonuria results when individuals lack a single enzyme involved in the catalysis of homogentisic acid. D) A single antibody gene can code for different related proteins, depending on the splicing that takes place post-transcriptionally.

b

Which of the following statements is true about protein synthesis in prokaryotes? A) Extensive RNA processing is required before prokaryotic transcripts can be translated. B) Translation can begin while transcription is still in progress. C) Prokaryotic cells have complicated mechanisms for targeting proteins to the appropriate cellular organelles. D) Unlike eukaryotes, prokaryotes require no initiation or elongation factors.