What makes something alive? Prokaryotic Cells. Two Main Classes of Cells. Eukaryotic Cell Structure. What features define living systems?

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1 What makes something alive? What features define living systems? 1. Composed of a common organization of atoms, molecules, cells... with emergent properties. 2. Share a similar chemical composition. 3. Made up of cells. 4. Capable of transforming energy. 5. Maintains homeostasis. 6. Capable of responding to stimuli. 7. Exhibits coordinated growth and development. 8. Capable of reproduction. 9. Capable of adaptation. 10. Can effect changes on its environment. Two Main Classes of Cells Prokaryotic (Bacteria and Archaea) Pro = Before ; Karyon = Kernel No nucleus, DNA coiled up inside cell Eukaryotic (Everything else) Eu = True DNA inside membrane bound organelle inside cell, the nucleus Prokaryotic Cells Bacteria: typical prokaryotes Size, shape and arrangement Flagella and fimbriae Cell wall Plasma membrane Bacterial chromosome Plasmids Ribosomes Role in the environment Prokaryotic and Eukaryotic Cell Structure Eukaryotic Cell Structure Plant and Animal Cell Structure Nucleus: the control center Cytoplasm and Ribosomes: site of protein synthesis Endoplasmic Reticulum: plumbing, lipid and protein synthesis Golgi Apparatus and the secretory pathway Lysosomes: 4 types of digestive activity Chloroplasts and Mitochondria: food and ATP energy Vacuoles: storage Cytoskeleton: structure and movement Plant Cell Wall: structure, osmosis and turgor pressure Family Photos: structural and functional specializations 1

2 Periodic Table Percentage of Elements found in things Levels of Organization in Biology Photosynthesis/Respiration Photosynthesis: Plants use carbon dioxide and produce starch and oxygen H 2 O + CO 2 = Starch/sugar + O 2 Respiration Animals use starch/sugar and oxygen, and produce carbon dioxide Starch/sugar + O 2 = H 2 O + CO 2 Reproductive strategies Sex? SEX: Internal fertilization (few or many) Nest laying (brooding) Broadcast spawning (mass release) This is mixing genes! NO SEX (asexual) Fission - parent splits Budding - parent develops small growth This is cloning! Sexual reproduction Introduce new genes Diversity in phenotype and genotype Resistance to disease Resistance to environmental change: Adaptation Hard to find a mate Picking the right one Mutations/problems Parental investment? Don t know exactly what you get 2

3 Sex? Some can do both! Asexual reproduction Fast Know exactly what you get Can spread your exact genes Cover an area quickly No need to find a mate No diversity (easily wiped out) Problem (if one exists) is reproduced Need a self recognition mechanism Combination of sexual and asexual reproduction can bring the best of both worlds Hermaphrodites: no need to find the right sex! These are organisms that are both sexes at once, or can change from male to female or female to male. Reproductive strategies Concentrations of solutions # of molecules in a specific volume Diffusion and Osmosis: Diffusion is the net movement of molecules from areas of high to low concentration Passive - requires no energy input Osmosis is the movement of water through a membrane that prevents solutes (large molecules) from passing. Net movement is from high to low concentrations 3-10 Diffusion Diffusion goes in all directions Hypertonic Hypotonic Isotonic 3

4 Osmosis- passive transport of water across a membrane Osmosis: problems with salt Osmoconformers - change with outside salinity Osmoregulators - regulate internal saltiness separate from the outside Isosmotic: same inside and outside Hyperosmotic: saltier inside Hypoosmotic: saltier outside Isosmotic Hyperosmotic: fresh water fish? Hypoosmotic: Marine Fish Sea Cucumber Surface area to volume ratio Tolerance limits Figure 3.2 Implications for heat loss Implications for floaters 3-1 4

5 Galápagos finches Figure 3.5 Warblers in tree Figure Source: Original observation by R. H. MacArthur. Population oscillations Figure 3.18 Predator-prey oscillations Figure Source: Data from D. A. MacLulich, Fluctuations in the Numbers of the Varying Hare (Lepus americus), Toronto: University of Toronto Press, 1937, reprinted J and S population curves Figure 3.20 Populations: what affects their size and growth? Density (#/area) - carrying capacity (K) Natality - birth rate Mortality - death rate Age distribution/sex ratio Spatial distribution Resource availability Species interactions Migration/emmigration 3-9 5

6 Community structure Figure 3.23 Trophic pyramid Figure Antarctic food web Figure 3.22 Sea Otters and Sea Urchins: a kelp forest paradigm Sea Urchins eat kelp, especially new recruits If kept in check, they eat drift kelp If populations expand, they will eat established kelp Sea Otters eat urchins, especially exposed ones They will keep sea urchin populations in check The Aleutian Island studies Sea Otters as a keystone predator 3-12 Ecosystem change: an example Taxonomy of two common species Reduction of coral = increase in Algae. This shifts functional Groups of species, and affects Primary productivity 3-3 6