BIOLOGY 2B03 Lecture Notes - Lecture 24: Gene Knockout, Chromatin, Nuclear Membrane
Document Summary
Robert horvitz said the number of cells in our body is an equilibrium number, since they are constantly going through apoptosis and division. Cancer can also result from too little cell death, as well as increased cell division. (50-7- billion cells die each day. Cell death is very important during embryogenesis. We start off with webbing at our feet and hands (week 6) but because of cell death, the webbing is removed by week 11. Here a tunel assay is used to detect apoptotic cells in this mouse paw. Tunel assay: dna in apoptotic cells have nicks and dna breaks and fluorescently labeled dutp can be incorporated into these nicks via an enzyme called terminal deoxynucleotidyl transferase. Tail loss during metamorphosis of frogs occurs via apoptosis which is stimulated by an increase in thyroid hormone. This is very similar to the tail loss seen during human embryogenesis.
