DNA Structure and Replication PDF

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12 - Oct 5 - study guide - Lecture notes 12...

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BIOL 211G Cellular & Organismal Biology Study Guide; October 5, 2017

DNA Structure and Replication 1. Review your prep handout and questions for DNA structure. Make sure you know the numbering for the carbons on the sugar in a nucleotide, and what is attached to each carbon in DNA and RNA. Answer the prep questions without looking at the handout or your notes… (same for all of these study questions) 2. Draw and label a chromosome after it has been replicated. During what stage of the cell cycle does it become replicated? 3. What does “semi conservative” mean? (in the context of DNA replication) 4. What do each of the following do during DNA replication? a. helicase b. SSBPs 5. What does DNA polymerase add nucleotides to? What provides this at the start of DNA replication? 6. Draw a replication fork- label all your ends. Now show (draw) how the leading and lagging strands are being synthesized. Now draw the same replication fork a little later on, and show what has happened on the leading and lagging strands. Now repeat this, but reverse your fork (or reverse the ends of the same fork). Now do it again, but make the fork an upside-down Y with the 5’ end on the bottom of the left strand. 7. For each of the following, categorize them as A (leading strand synthesis only), B (lagging only) or C (both leading and lagging- if both, are there any differences between leading and lagging?) (and go ahead and say what each does) -DNA pol III - ligase -helicase -Okazaki fragments -Primase -RNA primer -deoxyribonucleotides -ssBP 8. What enzyme “joins up” two Okazaki fragments after the primer has been removed? (and what enzyme removes the primer?) Ligase, DNA pol3 9. Is there any RNA primer on the leading strand? Explain your answer. And what is the “point” of having an RNA primer anyway? (i.e. why is a primer even needed?) no none on the leading strand because DNA pol 3 can move in that direction. On the lagging strand DNA pol 3 needs something to start from so that it can move in the opposite direction of the strand. RNA primer is the starting point for DNA pol 3

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BIOL 211G Cellular & Organismal Biology Study Guide; October 5, 2017

10. (see table on next page)…

Clicker Questions DNA is a polymer of a. amino acids b. nucleotides c. fatty acids d. monosaccharides Every nucleotide has a. sugar, amino acid, base b. amino acid, sugar , fatty acid c. amino acid, amino base, phosphate d. sugar, phosphate, base In DNA, what is on carbon #2 of the sugar? a. OH b. H Which bonds hold the 2 DNA strands in a DNA molecule together? a. ionic b. polar covalent c. nonpolar covalent d. hydrogen A DNA molecule is 20% G. What is the % A? a. 80% b. 30% c. 60% d. 20% 2

BIOL 211G Cellular & Organismal Biology Study Guide; October 5, 2017

Which pair is held together tighter in a DNA molecule? a. A & T b. A & C c. G & A d. G & C (explain your answer, and also be sure that you know which of the “pairs” in the answer are actual pairs that occur in DNA) A DNA strand has the sequence 3’ ATTGCC 5’- what is its complement? a. 5’ ATTGCC 3’ b. 5’ TAACGG 3’ c. 3’ TAACGG 5’ d. 3’ ATTGCC 5’

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