Characteristics of Biological Systems Regulation

1. Characteristics of Biological Systems • Regulation • Metabolic processes controlled to maintain homeostasis • Feedback regulation may be • Negative (Ex: Glucose metabolism) • Positive (Ex: Blood clotting)

2. Fig 1.13

3. Characteristics of Biological Systems • Growth and Development • Increase in cell number, size, both • Uniform or local growth • Determinate or indeterminate growth • Development: Changes in structure and/or function • Reproduction • Asexual – No gametes • Sexual • Genetic material from multiple individuals • Creates genetic variation – important for adaptation and evolution

4. Characteristics of Biological Systems • Evolutionary Adaptation • Change over multiple generations • Involves natural selection

5. Peppered Moth

6. Cellular Basis of Life • All organisms composed of cells • Organisms unicellular or multicellular • First observations of cork cells by Robert Hooke (1665) • First observations of microorganisms by Anton van Leeuwenhoek (~1665) • Cell Theory developed in 1838-1839 by Schleiden and Schwann using inductive reasoning • Later: Cells come from other cells, providing basis for growth, reproduction, and repair

7. Cellular Basis of Life • Cell types • Prokaryotic • Domains Archaea and Bacteria • No membrane-bounded organelles or membrane-bounded nucleus • DNA not separated from rest of cell • Most with tough exterior cell walls • Usually much smaller than eukaryotic cells • Eukaryotic • Domain Eukarya (Animalia, Plantae, Fungi, Protists) • Membrane-bounded organelles • DNA separated from rest of cell as chromosomes in nucleus • Some have cell walls (Plantae, Fungi)

8. Fig. 1.8

9. Transmission of Heritable Information • Basis for most species on earth is DNA (Deoxyribonucleic Acid) • Double-stranded backbone with four types of nucleotide building blocks • Organized into functional units called genes • Fundamental units of heredity • Transmission of genes  transmission of traits • All known forms of life use same genetic code • Genetic complement of an organism = genome

10. Fig. 1.11

11. Diversity of Life • About 1.8 million described species • 1,000,000+ insects • 290,000+ plants • 100,000+ fungi • 52,000 vertebrates • Estimated total: 10-200 million • Classification system: taxonomy • System developed by Carolus Linnaeus • Binomial nomenclature (Genus species) • Shared characteristics unite members of a taxon (group)

12. Fig. 1.14

13. Fig. 1.15

14. Diversity of Life • Unity in diversity • Similarities among distantly-related species

15. How can this happen? Fig. 1.16

16. Evolution • Concept underlies virtually all of modern biology • Explains unity and diversity of life • Involves responses by species (not organisms) to their environment • Charles Darwin (1859) – On the Origin of Species by Means of Natural Selection • Synthesis of information from biology and geology

17. Evolution • Descent with Modification • Species change from generation to generation • Contemporary species arose from ancestral species • Natural Selection • Mechanism for evolutionary change

19. Fig. 1.20