Bio 203 Final Exam Questions with Correct Answers 100% Verified What is the reason that closely linked genes are typically inherited together? - Correct Answers the likelihood of a crossover event between these two genes is low All female mammals have one active X chromosome per cell instead of two. What causes this? - Correct Answers activation of the XIST gene on the X chromosome that will become the Barr body In his transformation experiments, what did Griffith observe? - Correct Answers Mixing a heat-killed pathogenic strain of bacteria with a living nonpathogenic strain can convert some of the living cells into the pathogenic form In trying to determine whether DNA or protein is the genetic material of phage using radioisotopes, Hershey and Chase made use of which of the following facts? - Correct Answers DNA contains phosphorus, whereas protein does not Why is the new DNA strand complementary to the 3' to 5' strands assembled in short segments? - Correct Answers DNA polymerase can assemble DNA only in the 5' to 3' direction Cytosine makes up 42% of the nucleotides in a sample of DNA from an organism. Approximately what percentage of the nucleotides in this sample will be thymine? - Correct Answers 8% DNA replication is said to be semiconservative. What does this mean? - Correct Answers each new double helix consists of one old and one new strand What are the repetitive DNA sequences present at the ends of eukaryotic chromosomes called? - Correct Answers telomeres * A particular triplet of bases in the template strand of DNA is 5' CTA 3'. The corresponding codon for the mRNA transcribed is - Correct Answers 3' GAU 5' At a specific area of a chromosome, the sequence of nucleotides below is present where the chain opens to form a replication fork: 3' C C T A G G C T C G A A T G G 5' 1 / 2
An RNA primer is formed starting at the underlined T (T) of the template. Which of the following represents the primer sequence? - Correct Answers 5' A G C U U A C C 3' Accuracy in the translation of mRNA into the primary structure of a polypeptide depends on specificity in the - Correct Answers bonding of the anticodon to the codon and the attachment of amino acids to tRNAs A mutant bacterial cell has a defective aminoacyl-tRNA synthetase that attaches a lysine to tRNAs with the anticodon AAA instead of the normal phenylalanine. The consequence of this for the cell will be that - Correct Answers proteins in the cell will include lysine instead of phenylalanine at amino acid positions specified by the codon UUU When translating secretory or membrane proteins, ribosomes are directed to the ER membrane by - Correct Answers a signal-recognition particle that brings ribosomes to a receptor protein in the ER membrane Which of the following DNA mutations is the least likely to be damaging to the protein it specifies? - Correct Answers a substitution in the last base of a codon The figure below demonstrates the outcome of the following type of mutation: - Correct Answers frameshift causing extensive missense* Which of the following does not occur in prokaryotic gene expression, but does in eukaryotic gene expression? - Correct Answers A poly-A tail is added to the 3' end of an mRNA and a cap is added to the 5' end.The average length of a transcription unit along a eukaryotic DNA molecule is about 27kb nucleotide pairs, whereas an averaged- sized protein is about 400 amino acids long. What is the best explanation for this fact? - Correct Answers most eukaryotic genes and their RNA transcripts have long noncoding stretches of nucleotides that are not translated The tryptophan operon is a repressible operon that is - Correct Answers turned off whenever tryptophan is added to the growth medium If you were to observe the activity of methylated DNA, you would expect it to - Correct Answers have turned off or slowed down the process of transcription
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