BIO 181 Exam 4 questions n answers

BIO 181 Exam 4Chargaff's Rules - correct answer 1. adenine(A) always make bond with thymine(T) & guanine(G) always make bond with cytosine(C). 2. A always make double hydrogen bond with T & G always make triple hydrogen bond with C 3. concentration of purine = concentration of pyrimidine i.e. A+G=C+T 4.(A+T)/(G+C)= constant for a species 4 Nitrogenous Bases of DNA - correct answer Guanine-Cytosine Thymine-Adenine 4 Nitrogenous Bases of RNA - correct answer Guanine-Cytosine Uracil-Adenine Helicases - correct answer Helicase is an enzyme that breaks hydrogen bonds between nucleotides of DNA, unzipping a double -stranded DNA molecule. Topoisomerase - correct answer Enzyme that prevents the twisting of DNA ahead of the advancing replication fork by cutting the DNA, allowing it to unwind, and rejoining it. DNA Polymerase - correct answer Any enzyme that catalyzes synthesis of DNA from deoxyribonucleotide triphosphates (dNTPs). 1-removes RNA nucleotides of primer from 5 primed end and replaces them with DNA molecules 3-using parental DNA as a template, synthesizes new DNA strand by covalently adding nucleotides to the 3 primed end of a pre-existing strand or RNA primer DNA Ligase - correct answer An enzyme that joins pieces of DNA by catalyzing the formation of a phosphodiester bond between the pieces.