BSC 2010 Exam 3 Study Guide Chapter 16 Vocabulary 1 DNA Replication the process by which a DNA molecule is copied also called DNA synthesis 2 Transformation 1 the conversion of a normal animal cell to a cancerous cell 2 A change in genotype and phenotype due to the assimilation of external DNA by a cell When the external DNA is from a member of a different species transformation results in horizontal gene transfer 3 Bacteriophage a virus that infects bacteria 4 Virus an infectious particle incapable of replication outside of a cell consisting of an RNA or DNA genome surrounded by a protein coat capsid and for some viruses a membranous envelope 5 Double Helix the form of native DNA referring to its two adjacent antiparallel polynucleotide strands wound around an imaginary axis into a spiral shape a 6 Antiparallel referring to the arrangement of the sugar phosphate backbones in a DNA double helix they run in opposite 5 3 directions 7 Semiconservative model type of DNA replication in which the replicated double helix consists of one old strand derived from the parental molecule and one newly made strand a 8 Origin of replication site where the replication of a DNA molecule begins consisting of a specific sequence of nucleotides 10 9 Replication fork A Y shaped region on a replicating DNA molecule where the parental strands are being unwound and new strands are being synthesized Primer a short stretch of RNA with a free 3 end bound by complementary base pairing to the template strand and elongated with DNA nucleotides during DNA replication 11 DNA polymerase an enzyme that catalyzes the elongation of new DNA for example at a replication fork by the addition of nucleotides to the 3 end of an existing chain 12 Okazaki fragments a short segment of DNA synthesized away from the replication for on a template strand during DNA replication Many such segments are joined together to make up the lagging strand of newly synthesized DNA 13 DNA ligase a linking enzyme essential for new DNA replication catalyzed the covalent bonding of the 3 end of one DNA fragment such as an Okazaki fragment to the 5 end of another DNA fragment such as a growing DNA chain 14 Mismatch repair the cellular process that uses specific enzymes to remove and replace incorrectly paired nucleotides 15 Nuclease an enzyme that cuts DNA or RNA either removing one or a few bases or hydrolyzing the DNA or RNA completely into its component nucleotides 16 Telomere the tandem repetitive DNA at the end of a eukaryotic 17 Nucleotide a non membrane bounded region in a prokaryotic cell where chromosome s DNA molecule the DNA is concentrated 18 Chromatin the complex of DNA and proteins that makes up eukaryotic chromosomes When the cell is not dividing chromatin exists in its dispersed form as a mass of very long thin fibers that are not visible with a light microscope 19 Heterochromatin eukaryotic chromatin that remains highly compacted during interphase and is generally not transcribed 20 Euchromatin the less condensed form of eukaryotic chromatin that is available for transcription Understanding the Homework 1 In his transformation experiments what did Griffith observe a Mixing a heat killed pathogenic strain of bacteria with a living nonpathogenic strain can convert some of the living cells into the pathogenic form 2 How do we describe transformation in bacteria a Assimilation of external DNA into a cell 3 4 It became apparent to Watson and crick after completion of their model that the DNA molecule could carry a vast amount of hereditary information in a Sequence of bases In an analysis of the nucleotide composition of DNA what bases go with each other a A C G T 5 DNA replication is said to be semiconservative what does this mean a Each new double helix consists of one old and one new strand 6 Replication in prokaryotes differs from replication in eukaryotes because a Prokaryotic chromosomes have a single origin of replication whereas eukaryotic chromosomes have many 7 In E Coli there is a mutation in a gene celled dnaB that alters the helicase that normally acts at the origin What would you expect out of this mutation a No replication fork will be formed 8 Which enzyme catalyzes the elongation of a DNA strand in the 5 3 direction a DNA polymerase III 9 At a specific area of 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 G C A A T C C 5 An RNA primer is formed starting at the underlined T of the template What is the primer sequence a 5 A C G U U A G G 3 a Notice how the 5 3 match up The first one is read left to right and the answer is read right to left Remember that G goes with C and T goes with A but A goes with U 10 What is the function of DNA polymerase III a To add nucleotides to the 3 end of a growing DNA strand 11 The difference between ATP and the nucleoside triphosphates used during DNA synthesis is that the sugar ribose a The nucleoside triphosphates have the sugar deoxyribose ATP has 12 The leading and the lagging strands differ in that a The leading strand is synthesized in the same direction as the movement of the replication fork and the lagging strand is synthesized in the opposite direction 13 You briefly exposed bacteria undergoing DNA replication to radioactively labeled nucleotides When you centrifuge the DNA isolated from the bacteria the DNA separates into two classes One class of labeled DNA includes very large molecules thousands or even millions of nucleotides long and the other includes short stretches of DNA several hundred to a few thousand nucleotides in length These two classes of DNA probably represent a Leading strands and Okazaki fragments 14 What would you expect of a eukaryote lacking telomerase a A reduction in chromosome length in gametes 15 How do you describe eukaryotic chromosome a It consists of a single linear molecule of double stranded DNA plus proteins 16 If a cell were unable to produce histone proteins what would be a likely effect a The cells DNA couldn t be packed into its nucleus 17 What is true of DNA during interphase a It exists as chromatin and is less condensed than mitotic chromosomes i Chromatin is the term for the loosely coiled DNA observed in cells during interphase Even during interphase however parts of the chromosome may still be rather tightly coiled and packed 18 What is the order of increasingly higher levels of organization of chromatin a Nucleosome 30 nm chromatin fiber looped domain 19
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