BIOS 390 – Molecular Biology Week 2 Quiz Study Guide questions with answers

Question Set 1 (TCO 3) DNA replication is said to be semiconservative because Each daughter DNA molecule consists of one strand from the parent DNA molecule and one new strand. (TCO 3) DNA synthesis occurs in The 5' to 3' direction. (TCO 3) Which of the following statements is correct? The growth and development or healing of wound in an organism require new cells. The new cells in organism come from division of preexisting cells. DNA is the material in body which has all structural and functional information for body. Therefore each cell needs a full instruction in the form of DNA to work properly. So before cell division the DNA need to be replicate into two and transfer to new cell as a source of information. The DNA replication occur before cell division in S-phase of cell cycle. The DNA replication occur in nucleus of eukaryotic cell while prokaryotic cells do not have nucleus and their cell division occur in cytoplasm. Question Set 2 (TCO 3) During DNA replication, DNA ligase is most active on the lagging strand. This is because The lagging strands contain more short DNA segments than the leading strand, and these short segments are ligated together with DNA ligase (TCO 3) Phosphodiester bonds are formed between adjacent Okazaki fragments by DNA ligase. DNA polymerase is the enzyme that carries in the daughter nucleotides, and DNA helicase is the one that unwinds the double helix to open the replication fork. (TCO 3) Which of the following activities are unique for DNA polymerase I? DNA polymerase I has 2 enzymatic function. 1. Polymerase activity 5' to 3' DNA dependent and RNA dependent polymerization. 2. Exonuclease activity 5' to 3' exonuclease during nick translation 3' to 5' exonuclease in proof reading. Question Set 3 (TCO 3) Once bound to an origin of replication, the origin replication complex (ORC) recruits The first proteins to bind the DNA are said to “recruit” the other proteins. Two copies of an enzyme called helicase are among the proteins recruited to the origin. Each helicase unwinds and separates the DNA helix into single- stranded DNA. As the DNA opens up, Y-shaped structures called replication forks are formed. (TCO 3) Positive supercoils ahead of the replication fork are resolved by DNA gyrase. Question Set 4 (TCO 3) Replication licensing ensures that Control of DNA replication licensing in a cell cycle. To maintain genome integrity in eukaryotes, DNA must be duplicated precisely once before cell division occurs. A process called replication licensing ensures that chromosomes are replicated only once per cell cycle. (TCO 3) Pre-replication complex assembly (TCO 3) Find the incorrect statement. (Describe the replication processes.) Question Set 5 (TCO 3) Nucleotide selectivity and proofreading by DNA polymerase depends on When an incorrect base pair is recognized, DNA polymerase reverses its direction by one base pair of DNA and excises the mismatched base In eukaryotes only the polymerases that deal with the elongation (delta and epsilon) have proofreading ability (3' → 5' exonuclease activity). (TCO 3) Chromatin assembly factor 1 (CAF-1) is thought to aid replication by Chromatin assembly factors facilitate the process of depositing nucleosomes on daughter DNAs. CAF-I free H3H4 tetramers and then is recruited to newly replicated DNA by interactions with DNA sliding clamps. These sliding clamps (PCNA) are ring-shaped replication factors that encircle the DNA. It is released from the replication machinery as the replication fork moves. NAP-I free H2AH2B dimers. (TCO 3) Telomerase is a ribonucleoprotein complex. The RNA component of the complex Telomerase RNA component, also known as TERC, is an ncRNA found in eukaryotes, that is a component of telomerase - The enzyme used to extend telomeres. TERC serves as a template for telomere replication (reverse transcription) by telomerase.