22.1: The Birth of Cells

• Asymmetric cell division forms two different types of daughter cells from the same mother cell, while identical daughter cells may end up with different fates due to them receiving different signalsPluripotent stem cells are able to produce multiple types of descendant cells

• ES cells (cultured embryonic cells) can give rise to plenty of differentiated cell types, and can help which therapeutic uses and producing mice that are genetically altered

• Regeneration of cells can occur in stem cell populations that are in association with a large number of tissues

• Stem cells are not let into differentiation because certain signals (high level of B-catenin, from the Wnt signaling pathway) is employed to stop it

• The meristem of a plant is powered by plant stem cells, which give a rise to plenty of cell types and structures

• Precursor cells tend to lose their potential during development, causing them to become restricted in the number of cells they are able to form

• Germ layers during animal development:

  • Ectoderm

  • Mesoderm

  • Endoderm

• Germline cells power sperm and egg cells, and every other cell in the body is a somatic cell

22.2: Cell Type Specification in Yeast

• The three cell types of yeast are categorized through a specific set of transcription factors which show up in different combinations in the sites of the yeast genome

• Various transcription factors act as repressors or activators due to where they bind and the presence of other transcription factors

• Mating type pheromones binding by haploid yeast cells activates gene encoding proteins which generates a third type of yeast

22.3: Specification and Differentiation of Muscle

• Signal induced determination of certain mesoderm cells starts the growth and development of skeletal muscles

• bHLH dimerization along with other transcription factors modulates the binding of specific DNA regulatory sites

• The Swi/Snf chromatin remodeling complex powers the myogenic program that is driven by MRFs

• The scatter factor/hepatocyte growth factor (SF/HGF) induces the migration of myoblasts into limb buds

• Neurogenin is needed to form neural precursors and control the division into neurons or glial cells

22.4: Regulation of Asymmetric Cell Divison

• The polarization of dividing cells is needed for asymmetrical cell division

• The daughter cell produces Ash1 proteins after division and prevents HO endonuclease from being expressed

• The apical protein complex and two basal complexes are needed to localize for asymmetrical cell division in Drosophila neuroblasts

• The influence of asymmetry factors is exerted to control the orientation of the mitotic spindle

22.5: Cell Death and Its Regulation

• Apoptosis needs to be prevented through trophic factors so that cells can survive

• Apoptotic factors are regulated through:

  • Regulatory factors

  • Adapter proteins

  • Effector proteases

• Activated apoptotic factors protease and cleave specific intracellular substrates

• The activation of caspase is promoted through pro-apoptotic regulator proteins and suppressed by anti-apoptotic proteins

• Bcl2 contains both forms of apoptotic proteins in the family