Biology 330: Exam 2 (DNA Structure & Replication) questions and answers well illustrated.

Biology 330: Exam 2 (DNA Structure & Replication) questions and answers well illustrated. What two elements were identified in an acidic compound that was isolated from the nucleus by Johann Miescher? - correct answers.Nitrogen & Phosphorus Why proteins were thought to encode information that pertains to inheritable traits? - correct answers.1. Inheritable traits are diverse, and therefore molecules that encode these traits must be diverse 2. Proteins are made of 20 amino acids, which are structurally diverse Which two macro-molecules make the Bacteriophage structure? - correct answers.Proteins & DNA In the cell, which macro-molecules are labeled using 35S-methionine and 32P, respectively? - correct answers.35S used to label proteins 32P used to label DNA Describe Hershey and Chase's experiments, what conclusions were made from this study? - correct answers.They put different labels on radioactive markers onto the proteins and DNA of the bacteriophages and then sent them towards host cells to see whether proteins or DNA was being injected into the cells. After all this it was seen that proteins remained on the outer surface while DNA was injected into bacterial host cells. Conclusion: DNA carries inheritable material What is the DNA nucleotide made of? - correct answers.1. 5-carbon sugar called 2'-deoxyribose 2. Phosphate group 3. Nitrogen-containing bases Which bases are purines and pyrimidines? Explain why they are classified this way. - correct answers.Purines = adenine & guanine Pyrimidines = thymine & cytosine Purines have carbon and nitrogen forming the two rings while pyrimidines have carbon and nitrogen forming a single ring. Which base is found only in RNA and not DNA molecule? - correct answers.Uracil In his study of DNA structure, what major findings were made by Erwin Chargaff? - correct answers.Amount of adenine always equals amount of thymine Amount of guanine always equals amount of cytosine Linus Pauling built a DNA model and it failed. What was wrong with his proposed model? - correct answers.Phosphate groups facing the interior of DNA helix. Negatively charged phosphate groups facing inward would repel each other and DNA would be unstable. In their study of DNA structure, which three points did Watson and Crick focus on? - correct answers.1. DNA size 2. DNA shape 3. DNA bonding requirements What type of DNA did Maurice Wilkins laboratory work with? - correct answers.Dehydrated DNA What type of DNA did Rosalind Franklin's laboratory work with? - correct answers.Dry and wet DNA, the latter type is found in cells Based on Franklin's data, what were the calculated principal dimensions of the DNA molecule? - correct answers.Length of each full twist of the helix is 3.4 nm with the distance between adjacent bases being 0.34 nm. Based on Franklin's data, how many bases are per turn of the helix? - correct answers.10 per turn Based on Franklin's data, how many strands were thought to be twisted into a helix? - correct answers.2, 3, or 4 parallel stands Based on Franklin's data, what was the orientation of phosphate groups in the DNA molecule? - correct answers.Projecting outward Who recognized the significance of Rosalind Franklin's data? - correct answers.Maurice Wilkins How many stands is DNA molecule made of an in which direction do DNA strands run? - correct answers.2 strands of nucleotides Strands run in opposite directions Which groups are located on the outside in the DNA molecule? - correct answers.Sugar-phosphate Where are nitrogenous bases located in the DNA molecule, and what holds the bases together? - correct answers.Inside Held together by hydrogen bonds Which bacterial DNA polymerase was described by Arthur Kornberg? - correct answers.DNA polymerase 1 Explain what the origins of replication (ori) is? - correct answers.Binding sites for proteins that initiate the replication process What is the function of DNA polymerase III in bacteria? - correct answers.Required for DNA replication What is the function of DNA polymerase I in bacteria? - correct answers.Removes RNA primers and repairs the damaged DNA In eukaryotic cells, which DNA polymerases are found in the nucleus? - correct answers.DNA polymerases a, 8, and E In eukaryotic cells, which DNA polymerase is found in the mitochondria? - correct answers.DNA polymerase y Describe the two fundamental properties that are shared by all DNA polymerases? - correct answers.1. Synthesize DNA only in the 5' to 3' direction 2. All DNA polymerases add new nucleotides only to a pre-formed RNA primer strand that is hydrogen-bonded to a parent DNA template What is the enzyme called, which unwinds the parent DNA strand? - correct answers.Helicase What is the direction called in which the parent DNA strand unwinds? - correct answers.3' to 5' direction In which direction is a parent DNA strand copied? - correct answers.5' to 3' direction What is the function of small DNA binding proteins in DNA replication? - correct answers.Binds each single strand of DNA temporarily and stabilize it so that each unwound DNA template can be copied by DNA polymerase. What are the functions of Topoisomerase I and II? - correct answers.Topoisomerase I = breaks just one strand of DNA Topoisomerase II = breaks both strands of DNA simultaneously Explain what semi-conservative replication is. - correct answers.One strand of parental DNA is conserved in the new progeny of DNA molecule. Describe Reiji Okazaki's findings in regard to the copying of parental DNA template strands. - correct answers.Synthesis of the new DNA strand is continuous on just one parent DNA template while on the other parent DNA template, synthesis of the new DNA strand occurs in short nucleotide stretches.