Bio 203 Final Exam Questions and Answers Graded A

What is the reason that closely linked genes are typically inherited together? - 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? - activation of the XIST gene on the X chromosome that will become the Barr body In his transformation experiments, what did Griffith observe? - 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? - DNA contains phosphorus, whereas protein does not Why is the new DNA strand complementary to the 3' to 5' strands assembled in short segments? - 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? - 8% DNA replication is said to be semiconservative. What does this mean? - 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? - telomeres * A particular triplet of bases in the template strand of DNA is 5' CTA 3'. The corresponding codon for the mRNA transcribed is - 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' An RNA primer is formed starting at the underlined T (T) of the template. Which of the following represents the primer sequence? - 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 - bonding of the anticodon to the codon and the attachment of amino acids to tRNAs