Answers25.february
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February 25, 2005 Multiple choice questions (numbers in brackets indicate the number of correct answers) Chain termination DNA sequencing Requires a DNA polymerase Uses trideoxynucleotides Requires only one primer Degrades DNA before sequencing Cannot be automated Uses single-stranded DNA Introns Are always flanked by exons Occur only in genes Do not contain any meaningful sequence Can move out of a gene Often contain translation stop codons Help to identify genes in genomic sequences The ends of protein-coding genes Are not involved in gene expression Are not transcribed into RNA Are not translated into protein Consist mainly of repeated sequences Cannot be identified by sequence analyses Contain regulatory sequence elements Open reading frames (ORFs) Do not code for proteins Represent a complete gene Include intron sequences Denote genes of unknown function Can be found by computer analyses A crossover Might occur early in meiosis Might occur late in meiosis Involves 8 chromatids Involves 8 chromosomes Results in exchange of DNA segments Is the basis of genetic mapping The shotgun method (3) (3) (3) (2) (3 Is a sequencing technique Requires computers Yields a genome sequence Can only be used on large genomes Is faster than other genome sequencing approaches (3) Chromosome walking Is fast Can be used to close sequence gaps Occurs in mitosis Requires a genomic DNA library Is always done by PCR Is used in fluorescent in situ hybridization (FISH) (2) Expressed sequence tags (ESTs) Are random genomic sequences Are usually smaller than 50 bp Are cDNA sequences Can be used as genome markers Are attached to repeat sequences (2) Reporter genes Indicate the presence of stress conditions Are used to analyze gene expression Are all of bacterial origin Are used to delineate regulatory sequence elements Are usually highly expressed Homologous recombination Does not require any enzymes Occurs only in prokaryotes Requires identical DNA sequences Is used to construct recombinant DNA molecules Can be used to disrupt genes Occurs in mitosis Results in exchange of DNA segments (2) (3)
