Organization and Diversity of Life

  • Every cell is bordered by a plasma membrane

  • Functions of the Plasma membrane:

  1. holds contents of the cells in place

  2. takes in food and nutrients

  3. aids in building and exporting molecules

  4. Allows interactions with the neighboring environment and cells

  • Proteins and other molecules embedded in the plasma membrane help it perform its functions

There are two types of passive transport:

  • Diffusion: a form of passive transport in which a particle (the solute) is dissolved in a gas or liquid (the solvent), and moves from higher to lower solute concentration

    • Simple or facilitated'

  • AND osmosis

  • A positively charged potassium molecule has a higher concentration inside of the cell than outside the cell. Potassium naturally flows towards extracellular fluid, and it will take facilitated diffusion.

  • Eukaryotic cells formed from simple prokaryotes

  • There are two theories on how membrane bound organelles evolved: Invagination theory, endosymbiotic theory

  • Taxonomy: the classification, or organization, of living things

  • The organization of species is hierarchical

  • domain, kingdom, phylum, class, order, family, genus, species

  • The Biological species concept: “Species are populations of organisms that interbreed, or could possibly interbreed, with each other under natural conditions, and that cannot interbreed with organisms from other such groups” According to this definition of a species, species are not defined by how they look or their genetic relatedness

  • “Species are populations of organisms that interbreed, or could possibly interbreed, with each other under natural conditions, and that cannot interbreed with organisms from other such groups” The biological species concept focuses on reproductive isolation, not physical appearance or genetics.

  • Prezygotic Barriers- inability of the male reproductive cell to fertilize the
    female reproductive cell

  • Happens BEFORE the formation of the zygote (before the egg is fertilized

  • Pre=before
    Zygote= a fertilized egg

  • Postzygotic Barriers- occur after fertilization and prevent the production
    of fertile offspring (after a zygote is formed)

  • offspring must be reproductively viable for two individuals to be considered the same species. Non-fertile offspring of two species are known as hybrids