Lecture 28 - Lecture 28. Wed. (4-6-11) How to determine the...

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Lecture 28. Wed. (4-6-11)
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How to determine the length of S-phase Doubling time for a cell is the duration of one full cycle Human cell doubling time is about 24 hours for many human cells but not all Bacteria doubling time is often about 30 minutes 1 2 4 8 16 etc. Example: human diploid fibroblasts in culture Amount of time (hr) % of time M 0.5 3 G1 6.5 36 S 7.5 42 G2 3.5 19 42% of theses cells in an unsynchronized culture would be labeled with a pulse of 3 H thymidine. Why? M phase G1 S G2
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S-phase For these cells, S-phase is about 12 hours p.572 30 minute pulse of 3 H-thymidine
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What are we seeing? M phase G1 S G2 1 1 2 2 3 3 1. At time 1, the first cells in S-phase pick up radioactivity because they are incorporating 3 H thymidine into their DNA as it replicates. It takes them a long time before they are seen in mitosis (all of S and G2). They are the last to leave 2. At time 2, cells starting in the middle of S don’t take as long to reached mitosis 3. At time 3, the first cells to leave S phase arrived in mitosis. It doesn’t take them as long to get to mitosis as those at time 2 because they spend less time in S The time spent between time 1 and time 3 estimates the length of S-phase 0.5? 6? 7? 4? Look only at cells in mitosis for radioactivity
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The DNA mall. Where to go to get new Genes The owner of the mall wants to know: How much time do people spend in Sears? Macy’s
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This note was uploaded on 07/26/2011 for the course BIO 201 taught by Professor Janicke during the Spring '08 term at SUNY Buffalo.

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Lecture 28 - Lecture 28. Wed. (4-6-11) How to determine the...

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