Biology 1305 Final Question & Answers

What scientist were credited for their double-helix model for the structure of DNA, and that DNA was the substance of inheritance? - ANSWERSWatson and Crick Adenine and Guanine are - ANSWERSpurines Thymine cytosine and uracil are - ANSWERSpyrimidines Adenine pairs to ________ in DNA - ANSWERSThymine Adenine pairs to ________ in RNA - ANSWERSUracil Guanine pairs to ________. - ANSWERSCytosine Chargaff's rule states - ANSWERSin any organism the amount of A = G, and the amount of G = C DNA replication is described as semiconservative. Describe a semiconservative model of DNA replication - ANSWERSwhen a double helix replicates, each daughter molecule will have one old strand and one new strand Compare the three models of DNA replication - ANSWERSConservative--two parental strands come back together after acting as templates for new strands Semiconservative--two parental stands separate after acting as templates for new complimentary strands Dispersive--each strand of both daughter molecules contains a mixture of old and newly synthesized DNA Two strands of DNA are _____________. - ANSWERScomplementary Know these experiments - ANSWERSFrederick Griffith's Rat Experiment with Streptococcus Hershey and Chase phage experiment with E. Coli Matthew Meselson and Franklin Stahl replication model experiment Replication begins at special sites called ________________. - ANSWERSorigin of replication Differentiate between replication in eukaryotic and prokaryotic organisms. Why are they different? - ANSWERS--prokaryotic has one origin of replication --eukaryotic has many origins --because in a eukaryotic individual, more origins are needed to speed up the process because they have more DNA to be replicated What is a replication fork? - ANSWERSthe y-shaped region where new DNA strands are elongating What is/are the function(s) of helicase? - ANSWERSto untwist the double helix at the replication forks ___________ binds to and stabilizes single-stranded DNA until it an be used as a template. - ANSWERSsingle-strand binding protein ___________ corrects "overwinding" ahead of the replication forks by breaking, swiveling, and rejoining DNA strands. - ANSWERSTopoisomerase ___________ cannot initiate synthesis of a polynucleotide; they can only add nucleotides to the 3' end - ANSWERSDNA polymerases If you have 40% thymine, what percentage of G, C, and A do you have. - ANSWERSA- 40% C-10% G-10% Loosely condensed chromatin is called ___________. - ANSWERSeuchromatin What phase of the cell cycle is euchromatin found in? - ANSWERSInterphase Heterochromatin is ____________ found in the ____________ phase of a cell's cycle. - ANSWERShighly condensed; mitosis ________ is a complex of DNA and proteins found in the nucleus of prokaryotic cells. - ANSWERSchromatin What is a histone? - ANSWERSa protein responsible for the first level of DNA packing in chromatin An enzyme called _________ catalyzes the lengthening of telomeres in germ cells. - ANSWERStelomerase In nucleotide excision repair, _______ cuts out damaged parts of DNA. - ANSWERSnuclease _______ removes RNA nucleotides of primer from 5' end and replaces them with DNA nucleotides. - ANSWERSDNA polymerase I The lagging strand is synthesized as a series of segments called __________. - ANSWERSOkazaki fragments How are Okazaki fragments joined together? - ANSWERSDNA ligase DNA polymerase synthesizes a ___________ continuously, moving toward the replication fork. - ANSWERSleading strand Leading strand vs. Lagging strand - ANSWERS An enzyme called _______ can start an RNA chain from scratch and adds RNA nucleotides one at a time using the parental DNA as a template. - ANSWERSprimase The _______ is short (5-10 nucleotides long), and the 3' end serves as the starting point for the new DNA - ANSWERSprimer What is the job of dATP? - ANSWERSto supply adenine to DNA ________ add nucleotides only to the free 3' end of a growing strand; therefore, a new DNA strand can elongate only in the ___ to ___ direction. - ANSWERSDNA polymerases; 5' to 3' Telomeres, why are they important? - ANSWERSthey postpone the erosion of genes near the ends of DNA molecules Describe what it is meant to say antiparallel structure. - ANSWERSstrands are oriented in opposite directions DNA Pol I vs DNA Pol III - ANSWERSIII-- uses parental DNA as a template, synthesizes new DNA strand by covalently adding nucleotides to the 3' end of a pre-existing DNA strand or RNA primer I--removes RNA nucleotides of primer from 5' end and replaces them with DNA nucleotides _________ are links between genotype and phenotype. - ANSWERSproteins The process by which DNA directs protein synthesis, includes two stages: transcription and translation. - ANSWERSgene expression _________ is the synthesis of RNA under the direction of DNA. (This produces mRNA and happens in the nucleus.) - ANSWERSTranscription _________ is the synthesis of a polypeptide, which occurs under the direction of mRNA. (happen at the ribosomes in the cytoplasm) - ANSWERSTranslation