CELL BIO NOTES final.docx

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Health Sciences
Health Sciences 1002A/B
Anita Cramp

CELLBIOLOGYNOTESMIDTERMLECTURE 1 Introduction to Cell Biology Cell biology is studied because it provides you with the methods to isolate and maintain cells in vitro what to look for in them and how to separate cell organelles and identify proteins that drive biological processed The defining characteristic of a eukaryotic cell is the cellular segregation of cellular DNA within a defined nucleus bounded by a double membrane Cell Culture Cell culture is the technique used to grow cells or tissues outside the organism under strictly controlled conditionsIn order to grow cells in a culture cells need to be able to together to function collectively as a tissue in order to function This is accomplished through isolating cells from any tissue and breaking it down the cellcell and cellmatrix interactions and is done either mechanically by fragmenting the tissue or through enzymes such as trypsin and EDTA Proteins make cells stick together stick to surfaces or connective tissue the proteinprotein interactions need to be broken down and you can do that by adding an enzyme called trypsincleaves proteins on the outside of the cell so that cells will now break apart You could also add a chelating agentsucks up metal that function as cofactors that help proteins function as sticky protein helping cells stick together If the proteins are no longer sticky the cells will not be stuck to each other and will break apart After that you need to supply cells with food medianmaintain cellular processes and building blocks for the cellYou also need serum bloodripe productsinsulin used by cells in order to uptake glucose and growth factors help tell cells to stay alive and send signals to replicate and proliferate in the culture Cells are supplied with proper nutrients amino acids minerals vitamins salts glucose oetc serum insulin growth factors and grown usually at 37C in a CO incubator2Cells grown in different vessels Adherent cells stick to the dish Suspension cells like to swirl in the liquid and you can artificially swirl them by adding a suspension wand stirring stick or tumble the cells Room temp is not conducive to growth bc body temp is 37so put them in incubator and controlled for temp humidity and also profuse CO2 because cells are then exposed to atmospheric oxygen which is a much higherso extra CO2 to balance the oxygenand mimic gas conditions inside the bodyMimic the nutrients that cells get through the bloodstream are given through the media which will contain all the ingredients that our body will produce or absorb from the intestine PRIMARY CELL CULTUREcells taken directly from an organism These cells usually divide a limited number of times CONTACT INHIBITIONWhen cells get so close to each other they stop growing PASSAGING CELLS taking the cellsadd trypsin and some cells will come off and then add this diluted mixture to another median and have them grow again in another culture dish however these cells can grown only so many timesThe cells stop growing and dividing because of telomere shorteningPrimary cells can be used for experiments only so many times before they stop growing CELL LINEcells which are transformed and are able to grow indefinitely Also known as immortal cellsA cell line is transformed they dont have normal regulatory processes and checkpoints and keep on growing lose ability to contact inhibition and start to grow on top of each other EG Tumour a cell line is frequently derived from a tumour stHeLa cells waere the 1 cells that grew very easily and could understand how mitosis protein functions Morphology of Normal Vs Transformed Fibroblasts NORMAL Primary Cells TRANSFORMED Cell Line Elongated Rounded Aligned Hairlike processes Orderly packedDisorder Grow in parallel arrays Grow atop the other Contact Inhibition Loss of Contact inhibition Transformations can happen spontaneously due to a mutation or you can introduce oncogenes mutant versions of genes that override normal cell cycle mechanisms or apoptosis mechanisms Birth LineageDeath of Cells EmbryonicAdult cells A stem cell can divide and can give rise to 2 identical cells identical properties to the original stem cell A stem cell is not a functional tissue but it self renews gives rise to identical cells CELL LINEAGEstem cell can more of itself again and again SYMMETRIC DIVISIONcell divides and gives rise to 2 identical cells In the diagram above it shows that 1 stem cell continued on to being a stem cell whereas the other differentiated A external cue to 1 of the daughter cells causes changes in gene expression and patterns and differs morphological physiological and biochemical processand becomes a functional cells differs from other daughter cells of the original stem cell Maintain the balance of renewable and differentiable functional cells At any stage cells can decide to die due to external signal or selfprogrammed apoptosis Embryonic Stem Cells Embryonic stem cells can be maintained in culture and can form differentiated cell types Within blastocyst there is something called inner cell mass assymmetrical cluster of cells The inner cell mass can be cultured but you need a feeder cell which are usually fibroblast producing a mixed culture The fibroblast are really important bc they secret factors that help the inner cell mass to survive and important for the cells adhering
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