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Biology 1406 Chapter 1 – Evolution, the Themes of Biology, and Scientific Inquiry Biology – the study of life. There are certain facts and concepts about biology that are going to be central to the understanding of living things – 1. Life is a hierarchy – an order of ranks with each level building on the levels below. Campbell speaks to this on P. 2-3: A. The natural hierarchy Fig. 1.3, P. 2-3 – 1. Biosphere – the highest level of the natural hierarchy 2. Ecosystem 3. Community 4. Population 5. Organism 6. Systems 7. Organs 8. Tissues 9. Cells 10. Organelles 11. Molecules 12. Atoms – the lowest level of the natural hierarchy B. The man-made (Linnaean) hierarchy – for classification of life on Earth Fig. 1.12, P. 10 – 1. Kingdom – this is the top level. It is the most inclusive level This is one taxon that you are already familiar with – even in common usage, we refer to the “plant kingdom” or the “animal kingdom”. At this level, organisms are really, really different. Animals and plants differ at this greatest and most all encompassing level. 2. Phylum 3. Class 4. Order 5. Family 6. Genus 7. Species – this is the lowest level. It is the most exclusive level 2. (P. 4) Structure and function are intimately related in living things. Molecules and organisms both are shaped in order to perform the things they do the best. Fish gotta swim and birds gotta fly. Both are adapted to their environments and lifestyles – birds have light bones inside bodies that are powerhouses of energy. In many instances, we have been able to deduce much of how living things work by the way they are shaped or constructed. Indeed, these kinds of structural and functional considerations lead to what your text calls emergent properties (P. 3) – new and useful powers and abilities based on the arrangement and interactions of the parts of a system. 3. Cells are the basic unit of structure and function – the lowest level of structure that we can say is alive. All organisms are either composed of cells or are unicellular – one celled life forms. Fig. 1.4 on P. 4 There are two kinds of cells – Prokaryotic cells– like bacteria – very simple structure – nucleus not contained within a membranous boundary. Eukaryotic cells – everything else. Cells are much more complex – have a real nucleus within a nuclear envelope. You and I are eukaryotic!! Prokaryotic cells – primitive, rudimentary, primordial nucleus Eukaryotic cells – true, modern nucleus 4. (P. 5) DNA is the genetic material. All cells at some stage contain DNA. DNA structure leads to DNA function – inheritance. This is based on the ability of cells to copy the DNA faithfully, and to pass it on to the offspring. 5. (P. 7-9) Living things interact with and draw sustenance from their environment. All living things depend on each other for food which supplies energy and material nutrients. Living things use the energy in their environment to create orderly processes for themselves and return disorder to their environment in order to get rid of it. (heat, waste products, etc.) 6. (P. 9 – 15) There is unity in diversity. All of biology is about this topic – the most important concept in biology, because it explains how living things that are so different can show so much similarity between them. The term diversity refers to the millions of different species that exist – cows and pea plants, mosquitoes and oak trees. In all this diversity, there is unity as well. At the level of molecules, all living organisms use DNA as genetic material, most organisms use oxygen to breath, and as you will see later this semester, the genetic code is the same. This is best explained in biology by Charles Darwin’s principles of evolution by natural selection, outlined for you on P. 13 of your text. This is the single most important concept in all of biology, and it has held up firmly to the most rigorous scrutiny of science for the past 160 years. Evolutionary understanding brings sense to this hodge – podge of diversity, and explains the underlying unity as well.