Cell bio notes 4/18-4/20
Cell bio notes 4/18-4/20 BIOL 30603
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This 4 page Class Notes was uploaded by Mallory Notetaker on Friday April 22, 2016. The Class Notes belongs to BIOL 30603 at Texas Christian University taught by Dr. Akkaraju, Dr. Misamore, Dr. Chumley, Dr. McGillvray in Spring 2016. Since its upload, it has received 43 views. For similar materials see Molecular, Cellular, and Developmental Biology in Biology at Texas Christian University.
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Date Created: 04/22/16
SS cell bio notes 4/18-4/20 RhoA is important for helpoing set up or turn on contractile ring Theories for cleavage furrow location -astral stimulation -central spindle (found RhoA associated here) -astral relaxation- relax the rest of the actin in the cortex but keep just that region of the contractile ring build up How they found out that the spindle dictates furrow -experiment showed that even without chromosomes present, just with the spindle present, the cleavage furrow happened -showing kinetochores are not involved in cytokineses Rocking spindle- when the splitting chromosomes with attached microtubules rotate and divide in a different direction (change orientation) This is very important because it will determine which cells will become part of the new embryo ICM- inner cell mass, will become embryo Trophoblast- outer cells that won’t become a part of the embryo all machinery inside the cell needs to be replicated for both new daughter cells -we see this in new embryos and what can happen is certain things get put in one cell and not the other -when this happens, that will help determine what that cell will become -morphogens: something that generates morphology -an example of a morphogen: PAR2 -when PAR2 gets put in one cell and not the other, it will dictate the function of the P1 cell Two ways cell die 1. Necrosis- not intended to die, occurs when there is some sort of injury to the tissue, cell will repture and spill contents, can induce immune response 2. Apoptosis - intended to die, planned death -no massive immune response Apoptosis plays a huge role in development -the formation of our hands -the cells between our fingers go through apoptosis -frog tadpole tails also go through this Discovery of apoptosis -C. elegans -have about the same amount of cells -Fate map -following the fate of a cell -they kept seeing cells round up and disappear -there was 113 apoptotic events in every worm Caspase Cascade -start out with an inactive form of the enzyme (procaspase) -get cleaved and become active -initatior caspase starts the cascade -active executioner caspase Y can go on to cleave nuclear lamin -active executioner caspase Z can go on to cleave a cytosolic protien Intrinsic Pathway -from within the cell Extrinsic Pathway -from outside Intrinsic: Bcl2 Family - Bax and Bak -Activated Bax or Bak release a cytochrome c into cytoplasm and that will interact with an adaptor protein and create a 7 spoked wheel -the wheel will recruit procaspase 9 molecules and form the apoptosome (the procaspase will become active within this structure, will come together with another procaspase) Extrinsic pathway -can occur in old cells or in development -Fas death receptor are on the surfaces of mammalian cells -there are ligands that will bind to them (on killer lymphocyte) -the death receptor will interact with adaptor protein and also recruit proscapse-8 and all that will form DISC -then caspase-8 will become activated and the activation of exectuioner caspases will occur and apoptosis can happen Meiosis Reproduction -Sexual -Asexual Asexual- making a copy of itself Advantage- if things are going good, you will produce the exact same thing You undergo meiosis and create a cell that will only get one copy of their DNA = gametes -those cells come together to make a zygote = diploid -have one copy of each parents DNA -then it will undergo mitosis to create the multicellular organism Mitosis -chromosome duplication -cell division -end result = two diploid cells Meiosis -chromosome duplication -cell division -cell division again -end results = four haploid cells Meiosis is broken up into meiosis I and meiosis II -you get 4 nonidentical haploid cells Prophase I -the duplicated sister chromatids (exact copies of themselves) -these find their homologous pairs and bind to each other by chiasma -homologous recombination takes place = portions of moms chromosomes mixes with parts of dads Metaphase I -homologous pairs line up on metaphase plate Anaphase I -microtubules pull homologous pairs apart Telophase I and cytokinesis -give two daughter cells = end of meiosis I Both daughter cells enter Meiosis II Metaphse II: sister chromatids get lined up Anaphase II: sister chromatids get pulled apart Telophase II and cytokinesis: gives 4 haploid daugther cells = end of meiosis II -each chromosomes in each cell is different than moms or dads original In mitosis: in metaphase there would be 46 chromosomes lined up on metaphase plate In meiosis: there are 23 chromosomes lined up Bivalent formation - tetrad -sister chromatids attached to each other and also bound to its homologous pair Crossing over -you get breaks int he chromosomes and allows them to reattach to the other homologous pair at the same site -chiasma One of the stages in here is diplatene (will talk about later) Metaphase I -duplicated homologous chromsomes pair befor elining up at the metaphase plate Anaphase I -you have chiasma keeping homologous pairs attached but then get pulled apart