exam 4 bio 203 – Flashcards
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Garrod hypothesized that "inborn errors of metabolism" such as alkaptonuria occur because
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genes dictate the production of specific enzymes, and affected individuals have genetic defects that cause them to lack certain enzymes
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A particular triplet of bases in the template strand of DNa is 5' AGT 3'. The corresponding codon for the mRNA transcribed is
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3' UCA 5'
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Transcription of the structural genes in an inducible operon
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starts when the pathway's substrate is present
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A student wants to clone a DNA sequence of ~200 kb in length. Which vector would be appropriate?
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a BAC
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Which of the following is one of the technical reasons why gene therapy is problematic?
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Transferred genes may not have appropriately controlled activity
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At a specific area of a chromosome, the sequence of nucleotides below is present where the chain opens to form a replication fork:
3' CCTAGGC(T)GCAATCC 5'
An RNA primer is formed starting at the underlined T (T) of the template. Which of the following represents the primer sequence?
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5' ACGUUAGG 3'
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What is the reason that closely linked genes are typically inherited together?
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the likelihood of a crossover event between these two genes is low
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All female mammals have one active X chromosome per cell instead of two. What causes this?
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activation of the XIST gene on the X chromosome that will become the Barr body
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In his transformation experiments, what did Griffin observe?
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Mixing a heat-killed pathogenic strain of bacteria with a living nonpathogenic strain can convert some of the living cells into the pathogenic form
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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?
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DNA contains phosphorus, whereas protein does not
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Why is the new DNA strand complementary to the 3' to 5' strands assembled in short segments?
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DNA polymerase can assemble DNA only in the 5' to 3' direction
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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?
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8%
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DNA replication is said to be semiconservative. What does this mean?
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each new double helix consists of one old and one new strand
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What are the repetitive DNA sequences present at the ends of eukaryotic chromosomes called?
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telomeres
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A particular triplet of bases in the template strand of DNA is 5' CTA 3'. The corresponding codon for the mRNA transcribed is
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3' GAU 5'
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Accuracy in the translation of mRNA into the primary structure of a polypeptide depends on specificity in the
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bonding of the anticodon to the codon and the attachment of amino acids to tRNAs
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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
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proteins in the cell will include lysine instead of phenylalanine at amino acid positions specified by the codon UUU
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When translating secretory or membrane proteins, ribosomes to a receptor protein in the ER membrane by
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a signal-recognition particle that brings ribosomes to a receptor protein in the ER membrane
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Which of the following DNA mutations is the least likely to be damaging to the protein it specifies?
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a substitution in the last base of a codon
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Which of the following does not occur in prokaryotic gene expression, but does in eukaryotic gene expression?
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crossing over
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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?
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most eukaryotic genes and their RNA transcripts have long noncoding stretches of nucleotides that are not translated
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The tryptophan operon is a repressible operon that is
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turned off whenever tryptophan is added to the growth medium
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If you were to observe the activity of methylated DNA, you would expect it to
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have turned off or slowed down the process of transcription
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In eukaryotes, general transcription factors
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bind to other proteins or to a sequence element within the promoter called the TATA box
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which of the following best describes siRNA?
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short double-stranded RNA, one of whose strands can complement and inactivate a sequence of mRNA
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The product of the bicoid gene in Drosophila provides essential information about
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the anterior-posterior axis
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which of the following statements describes proto-oncogenes?
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they are cellular genes responsible for normal cell growth and division
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mutations in the ras gene may lead to
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production of a hyperactive Ras protein and increased cell division
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BRCA1 and BRCA2 are considered to be tumor-suppressor genes because
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their normal products participate in repair of DNA damage
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genomic imprinting, DNA methylation , and histone acetylation are all examples of
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epigenetic phenomena
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the phenomenon in which RNA molecules in a cell are destroyed if they have a sequence complementary to an introduced double-stranded RNA is called
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RNA interference
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The following enzyme is necessary to generate a complementary DNA library:
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reverse transcriptase
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Agent Scully was able to complete the following technique (in under two hours) combining gel electrophoresis of DNA fragments with nucleic acid hybridization in order to demonstrate the existence of alien DNA which had integrated into her own DNA
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Southern blot
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Scientists can utilize the following techniques in order to get DNA inside a target cell
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electroporation
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The following technique requires heating, cooling, and replication in order to bring about a chain reaction that produces an exponentially growing population of identical DNA molecules
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polymerase chain reaction
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A gene that contains introns can be made shorter (but remain functional) for genetic engineering purposes by using
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reverse transcriptase to reconstruct the gene from its mRNA
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In order to insert a human gene into a plasmid, both must
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be cut by the same restriction enzyme
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Which of the following is true of embryonic stem cells but not of adult stem cells?
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they can give rise to all cell types in the organism
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Cold case detectives are investigating a homicide that took place 30 years ago. In reexamining the evidence, they find a tiny spot of blood on the victim's clothing that was unlikely......... What technique would the blood lab technicians use in their examination of this tiny, degraded blood sample?
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polymerase chain reaction to amplify the DNA
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DNA microarrays have made a huge impact on genomic studies because they
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allow the expression of many or even all of the genes in the genome to be compared at once
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Relatively short DNA fragments can be sequenced using
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dideoxyribonucleotides tagged with a distinct fluorescent label
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What methodology is normally utilized to insert a cloned gene into bone marrow cells from patients to correct a defective gene?
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infection with a retrovirus carrying the RNA version of the normal gene
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Gene function can be determined by disabling the gene using
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in vitro mutagenesis
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Dr. Feuer would like to clone himself....
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all of the above
