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BIO 340 Exam 3-Lecture 15

front 1 What's the building blocks of DNA?	back 1 Nucleotides
front 2 What do nucleotides consist of?	back 2 Nitrogenous base, pentose sugar, and phosphate group
front 3 What would be the complementary DNA strand for the following DNA sequence? 5'-GCGTATG-3' A. 5'-CGCATAC-3' B. 5'-CATACGC-3' C. 5'-GTATGCG-5'	back 3 B. 5'-CATACGC-3'
front 4 What type of replication is used to reproduce DNA?	back 4 Semiconservative Replication

front 5 What does conservative replication consist of?	back 5 The original helix is conserved and two newly synthesized strands come together
front 6 What does semiconservative replication consist of?	back 6 Each replicated DNA molecule consists of one "old" strand and one new strand
front 7 What does dispersive replication consist of?	back 7 Parental strands are dispersed into two new double helices
front 8 What type of replication would result in these two strands after one round of replication?	back 8 Conservative Replication

front 9 What type of replication would result in these two strands after one round of replication?	back 9 Semiconservative Replication
front 10 What type of replication would result in these two strands after one round of replication?	back 10 Dispersive Replication
front 11 What was learned/gained from the Meselson and Stahl experiment?	back 11 DNA replication is semiconservative in prokaryotes and that each new DNA molecule consists of one old strand and one newly synthesized strand
front 12 Does semiconservative replication only occur in prokaryotes or various other species as well?	back 12 Various other species as well

front 13 What are the different ways in which semiconservative replication can occur?	back 13 In either a circular or linear fashion depending on chromosome shape
front 14 Which of the following would result from a third round of replication using the methods of Messelson and Stahl? A. One heavy band, one light band, and one intermediate band B. One light band and one intermediate band C. One light band D. One heavy band	back 14 B. One light band and one intermediate band
front 15 Where does DNA replication begin?	back 15 At the origin of replication
front 16 Where/how is the replication fork created?	back 16 Where replication occurs, the strands of the helix are unwound thus producing a replication fork

front 17 Replication is _____, therefore there are two replication forks	back 17 Bidirectional
front 18 The length of DNA that is replicated following one initiation event at a single origin is called?	back 18 Replicon
front 19 How many circular DNA does bacteria have and at how many points does DNA synthesis originate at?	back 19 Bacteria has a single circular DNA and DNA synthesis originates at a single point
front 20 How many replicons does an entire bacterial chromosome constitute?	back 20 One replicon

front 21 In eukaryotes, DNA replication begins at one or many sites?	back 21 Many sites
front 22 What does DNA polmerase do?	back 22 DNA polymerase catalyzes DNA synthesis and requires a DNA template and all four deoxyribonucleoside triphosphates in order to help catalyze the polymerization of dNTPs into a DNA strand
front 23 How do nucleotides arrive?	back 23 They arrive as nucleosides
front 24 True or False: DNA bases do not arrive with an energy source for bonding	back 24 False, DNA bases arrive with their own energy for bonding

front 25 What is the bonded enzyme called?	back 25 DNA polymerase
front 26 What are nucleosides?	back 26 DNA bases with P-P-P which is energy for bonding
front 27 In what direction does chain elongation occur?	back 27 5' to 3'
front 28 What are DNA polymerases?	back 28 Enzymes that help catalyze in the polymerization of dNTPs into a DNA strand

front 29 What can DNA polymerases 1, 2, and 3, do to a DNA strand (primer)? What can they not do?	back 29 Can: elongate an existing DNA strand Cannot: initiate DNA synthesis
front 30 What do all DNA polymerases (1, 2, and 3) possess? (activity type?) and what does it enable them to do?	back 30 Possess 3' to 5' exonuclease activity that allows them to proofread newly synthesized DNA and remove and replace incorrect nucleotides
front 31 What kind of exonuclease activity does DNA polymerase 1 possess?	back 31 Only DNA polymerase I demonstrates 5' to 3' exonuclease activity, which allows it to excise primers and fill in the gaps left behind.
front 32 Which DNA polymerases possess 5'-3' polymerization?	back 32 DNA polymerases I, II, and III

front 33 Which DNA polymerases possess 3'-5' exonuclease activity?	back 33 DNA polymerases I,II, and III
front 34 Which DNA polymerases possess 5'-3' exonuclease activity?	back 34 DNA polymerase I
front 35 How many molecules of polymerase/cell are found in DNA polymerase I and III?	back 35 DNA polymerase I: 400 DNA polymerase III: 15
front 36 Which DNA polymerase is responsible for the 5' to 3' polymerization essential in vivo?	back 36 DNA polymerase III

front 37 All known bacterial DNA polymerases _____ A. can initiate DNA chain synthesis B. have 5' to 3' polymerization activity C. have 3' to 5' polymerization activity D. All of the above	back 37 B. have 5' to 3' polymerization activity
front 38 Which polymerases are the main DNA builders?	back 38 DNA polymerase II and III
front 39 Which polymerases are responsible for editing, repair and primer removal?	back 39 DNA polymerase I
front 40 How often do errors occur during cell copies and bases when dividing?	back 40 Only 1 error per 100 million bases

front 41 What are the seven key issues that must be resolved during DNA replication?	back 41 1. unwinding of the helix 2. reducing increased coiling generated during unwinding 3. synthesis of a primer for initiation 4. discontinuous synthesis of the second strand 5. removal of the RNA primers 6. joining of the gap-filling DNA to the adjacent strand 7. proofreading
front 42 Where does DnaA bind to? And what is it responsible for?	back 42 DnaA binds to the origin of replication and is responsible for the initial steps in unwinding the helix
front 43 What helicases further open and destabilize the helix?	back 43 DnaB and DnaC
front 44 What do the single-stranded binding proteins do?	back 44 Single-stranded binding proteins stabilize the open conformation

front 45 What do topoisomerases do in DNA replication?	back 45 Topoisomerases remove positive supercoils that normally form ahead of the growing replication fork
front 46 What are used to achieve a high speed replication of both the leading and lagging strands?	back 46 DNA polymerases utilize sliding clamps which move along the template without falling off
front 47 What are clamp loaders?	back 47 Clamp loaders are ATP-fueled moelcular machines that open the sliding clamp, load them onto primed DNA, and unload them at the appropriate time
front 48 What does DNA polymerase III require to elongate a polynucleotide chain?	back 48 Requires a primer

front 49 What does primase do to an RNA primer	back 49 Primase synthesizes an RNA primer which provides the free 3' hydroxyl required by DNA polymerase III
front 50 What does DNA polymerase I do?	back 50 It removes the primer and replaces it with DNA
front 51 True or False: Priming is a universal phenomemnon during initiation of DNA synthesis?	back 51 True
front 52 Which strand serves as a template for continuous DNA synthesis?	back 52 Leading strand

front 53 Which strand undergoes discontinuous DNA synthesis?	back 53 Lagging strand
front 54 How is the lagging strand synthesized?	back 54 As Okazaki fragments with an RNA primer
front 55 What does DNA polymerase I do?	back 55 It removes the primers on the lagging strand and its fragments are joined by DNA ligase
front 56 What is proofreading?	back 56 DNA polymerase uses structure of DNA to catch errors. Two stranded molecule passes through the DNA polymerase once synthesis is complete. If there's a wrong base it's detected and replaced.

front 57 What would happen if DNA polymerase used a single stranded DNA as a temple and the completed double strand didn't continue to interact with the enzyme after synthesis?	back 57 The number of errors in DNA replication would be much higher
front 58 What is an integral part of DNA replication?	back 58 Proofreading and error correction
front 59 What does DNA synthesis at a single replication fork involve?	back 59 DNA polymerase III, single stranded binding proteins, DNA gyrase, DNA helicase, RNA primers
front 60 Is DNA replication more complex in Eukaryotes or Prokaryotes?	back 60 Eukaryotes is more complex

front 61 What are some features shared between eukaryotic replication and replication in bacteria?	back 61 Double stranded DNA is unwound at replication origins, replication forks are formed, bidirectional synthesis creates a leading and lagging strand, eukaryotic require four dNTPs, a template and a primer
front 62 Why is Eukaryotic DNA replication more complex than that of prokaryotes?	back 62 They have more DNA that prokaryotic cells, chromosomes are linear, and DNA is complexed with proteins
front 63 How many origins of replication do eukaryotic chromosomes have?	back 63 Multiple origins of replication are had to allow the genome to replicated in a matter of minutes to a few hours
front 64 Yeast genomes contain 250-400 origins which are called?	back 64 Autonomously replicating sequences (ARSs)

front 65 When does the cell growth checkpoint occur in the cell cycle?	back 65 Occurs toward the end of the growth pahse
front 66 When does the DNA synthesis checkpont occur in the cell cycle?	back 66 Occurs during the synthesis (S) phase
front 67 When does the mitosis checkpoint occur in the cell cycle?	back 67 Occurs during the mitosis phase (M)
front 68 What is the checkpoint?	back 68 Checkpoint is a mechanism that halts progression throughout the cell cycle until a critical process like DNA replication is complete or until DNA damage is repaired

front 69 What happens when a checkpoint is satisfied?	back 69 the cell cycle continues
front 70 What type of proteins play a role in controlling the cell cycle?	back 70 Cyclins and cyclin-dependent kinases
front 71 What do complexes between cyclins and CDKs do to the cell?	back 71 Cause the cell cycle to advance
front 72 What do CDKs do?	back 72 They're regulatory molecules that alter the activity of many other proteins through phosphorylation. CDKs need o pair with cyclins to be active

front 73 What happens if cyclins are absent?	back 73 If cyclins are absent then CDKs do not function
front 74 What are the four separate proteins that assemble in an ordered fashion in Pre-RC?	back 74 ORC (origin recognition complex), Cdc6 and Cdt1 (helicase loading proteins), and Mcm 2-7 (complex, helicase)
front 75 Does the pre-RC initiate DNA unwinding before or after the S phase?	back 75 pre-RC initiates DNA unwinding after the cell enters the S phase
front 76 What are telomeres?	back 76 Telomeres are at the ends of linear chromosomes and consist of long stretches of short repeating sequences that preserve the integrity and stability of chromosomes

front 77 Telomeres provide ____ at chromosome ends but are _____ to ____	back 77 provide structural integrity at chromosome ends but are problematic to replicate
front 78 The enzyme telomerase directs synthesis of? What does it result in?	back 78 TTGGGG and results in formation of hairpin structure
front 79 In most eukaryotic somatic cells is the telomerase active? What happens to eat with each cell division?	back 79 It is not active, and with each cell division the telomeres shorten and erode (causing further cell division to stop)
front 80 What do malignant cells maintain? Are they mortalized or immortalized?	back 80 They maintain telomerase activity and are immortalized.