Sul Ross State University Sul Ross State University

Important Biological Principles and Concepts

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Application of physical and chemical properties
     1. Living systems and their constituents obey physical and chemical laws
     2. All organisms capture, store, and transmit energy
     3. There is a biochemical and molecular unity of living systems

Concept of evolution
     4. Plants and animals evolve by the mechanism of natural selection (Darwin, 1859)
     5. All organisms are adapted to their habitat
     6. Plants and animals that have many morphological characters in common share a common descent
     7. Embryos of plants and animals tend to go through stages resembling embryos of their ancestors
     8. Evolution is irreversible (Dollo's law)

Biogenesis
     9. Life comes from life (Virchow, 1858)
   10. Reproduction is a property of living systems

Cell theory (Schleiden and Schwann, 1838-1839)
   11. Cells are the fundamental functional units of life
   12. Cells contain differentiated and functionally interdependent structures

Gene theory
   13. The principle of hereditary transmission is that all organisms inherit a structural and functional
            organization from their progenitors
   14. The gene is the fundamental unit of inheritance and inheritance obeys Mendel's laws (1865)
   15. Gene frequencies in a population can remain stable under certain conditions
   16. Gene frequencies in a population can change
   17. DNA is the substance that contains the inherited information
   18. The genetic code is in a linear order to bases on the DNA strand
   19. Transcription and translation of genetic information are mediated by RNA
   20. A gene corresponds to the formation to synthesize a polypeptide (e.g., an enzyme)

Growth, life cycle, and differentiation
   21. Growth is a fundamental characteristic of life
   22. All organisms have a characteristic life cycle that they pass through as they grow
   23. All organisms develop a characteristic body plan
   24. In multicellular organisms, while all cell nuclei are genetically alike, the differentiated cells
            are not alike responses and relations to the environment of a cell or organism
   25. Irritability is a characteristic of life
   26. Cells in a multicellular organism communicate with and affect each other
   27. All organisms interact with their environment

ASSIMILATE AS MANY OF THESE PRINCIPLES AND CONCEPTS AS POSSIBLE AS YOU PROGRESS THROUGH THE COURSE