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Lecture 9

Lecture 9 - Lecture#9 Tuesday Announcements-1 MIDTERM =...

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Lecture #9 – Tuesday, 4/29/2008 - 1 - Announcements: MIDTERM = NEXT TUESDAY, MAY 6 (just in case you forgot) - Midterm : Scantrons will be provided, bring a picture ID and pencil. - On the Lecture 4 (4/10/08) notes, o I wrote: v-sis is a gene that encodes PDGF. The mutated form leads to the overexpression PDGF . o What I meant to say was: v-sis is a viral oncogene that can mutate the endogenous cell c-sis proto-oncogene, causing it to be overexpressed; which then leads to autocrine signaling, etc. Last time: - p53 and apoptosis - How cell death can be a mechanism for cell survival This time: powerpoint based, but all slides are from pictures in the textbook. Table 9.2: Key target genes of p53 - p53 is initially involved in the induction of growth arrest and cell survival at low levels. o It leads to the initiation of apoptosis pathways at high levels of expression. Movie from book: - When undergoing apoptosis: o Cells shrink o Bleb o Break up into smaller pieces of lipid membrane bound fragments of DNA and proteins. Apoptosis vs. Necrosis: - Apoptosis – Coherent, organized, well regulated cell suicide o The cell facilitates its own destruction and clearance: It occurs through the expression of specific gene programs that will initiate cell decomposition. Its neat packaging of cell parts allows easy clearance by macrophage phagocytosis. o Wouldn’t want whole dead cells or cell debris lying around for the same reason you wouldn’t want dead bodies lying around. This can contribute to illness. - Necrosis – Cell death that results from catastrophic injury/rapid environmental changes (i.e. burns). o It is sudden death. And because it occurs as a result of rapid and large insult, there are usually many cells that die as a result.
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Lecture #9 – Tuesday, 4/29/2008 - 2 - Apoptosis is an individual and internal response. (But can be occurring in multiple cells at same time.) o Occurs when the cell dies without the time or ability to carry out apoptosis. o Because it involves the death of more cells, more macrophages and other immune cells are needed to clear the cell debris. Lots of macrophage infiltration into tissue is called inflammation . Inflammation is related to necrotic response. Figure 9.18a: Apoptotic vs. normal cell (apoptotic cell on bottom). Figure 9.18b: Stained nuclei of apoptotic vs. normal cells (apoptotic cells on right). - Note the overall structure of nuclei is condensed. - Mammalian DNA is long and linear. It is broken up into smaller pieces by enzymes; this can be seen in a gel. Figure 9.18c: DNA Laddering - Ad-EGFP: non-apoptotic cells - Ad-Lats2: apoptotic cells. Lats2 is a pro-apoptotic protein. - Apoptotic DNA is fragmented into a ladder. Figure 9.19: Normal functions of apoptosis in development.
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Lecture 9 - Lecture#9 Tuesday Announcements-1 MIDTERM =...

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