Lecture 2 - Cytoplasm Flashcards
What is a Zygote?
A single cell formed by the merger of a spermatozoon with an oocyte at fertilisation.
What are blastomeres and embryonic stem cells?
The first zygotic cellular division produces cells called blastomeres and as part of the embryos inner cell mass, blastomeres give rise to all tissue types of the fetus. Explanted to the tissue culture cells of the inner cell mass are called embryonic stem cells.
What is differentiation of cells?
Mosts cells in the foetus undergo a specialisation process called differentiation, in which the cells differentially express sets of genes that mediate specific cytoplasmic activities, becoming very efficient at specialised functions, and change shape accordingly.
What is the Plasma Membrane?
The membrane allows for the passage of material into and out of the cell and facilitates the transport of specific molecules. The membrane envelopes all eukaryotic cells and consists of phospholipids, cholesterol and proteins, with oligosaccharide linkages between the phospholipid and protein molecules. One important function of the cell membrane is to keep constant the ion content in the cytoplasm, which differs from the extracellular fluid.
What are integrins?
Certain plasma membrane proteins, the integrins, are linked to both the cytoskeleton and the extra cellular matrix components allow for the exchange of material in both directions between the cytoplasm and the ECM.
What is the size of plasma membranes?
7.5-10nm in thickness and are only visible with electron microscopes.
What is the structure of the membrane phospholipids?
The membrane phospholipids are amphipathic, consisting of two non-polar (hydrophobic or water repelling) long chain fatty acids linked to a charged polar (hydrophilic or water attracting) head which has a phosphate group. Phospholipids are most stable in double layers (bilayer) with the hydrophobic fatty acid chains located in the middle region away from the water and the phosphate heads contacting the water. Molecules of Cholesterol, a sterol lipid, insert at varying densities among the closely packed phospholipid fatty acids, restricting their movements and modulating the fluidity of all membrane molecules.
Which proteins are synthesised by the Rough ER
Synthesises proteins for exocytosis, proteins for plasma membranes and proteins for lysosomal proteins.
