Characteristics of Life: Distinguishing Living from Non-Living

1. What is Life? Chrysocyon brachyurus (Maned Wolf) Adansonia grandidieri (Baobob)

2. Learning Objectives • At the end of this unit, a student should be able to… • Describe the characteristics shared by all living things and articulate how these are used to distinguish between living from non-living things. • List the levels of the hierarchical organization of life in order and identify where a particular process or object is “located” within it.

3. Characteristics of Life • What are the defining characteristics of life? • Which qualities are shared by ALL living things? • Coming up with a definition of life is not as easy as you’d think! • Learning Objective: Distinguish between living and nonliving things by describing the features that characterize living organisms

4. Characteristics of Life Living things: • maintain hierarchical levels of order • reproduce using DNA/RNA • grow and develop over time • sense and respond to internal and environmental stimuli • maintain homeostasis, regulate metabolism • adapt and evolve • process energy

5. “maintain hierarchical levels of order” atoms molecules cells living things are composed of one or more CELLS Basic unit of life Most forms of life are unicellular Characteristics of Life

6. Characteristics of Life • “reproduce using DNA/RNA” • cells only come from other cells • DNA replicates (mitosis) • Cell contents replicate • 1 cell produces 2 genetically identical cells

7. Characteristics of Life • “reproduce using DNA/RNA” • Deoxyribonucleic Acid • consists of 4 nucleotides or bases (A,C,G,T) • stores information • ex. Human genome ~3,200,000,000 base pairs

8. Characteristics of Life • “grow and develop over time” • Biological growth involves an increase in size of cell and/or number of cells • Development includes all changes during an organism’s life • can be influenced by environment

9. Characteristics of Life • “sense and respond to internal and environmental stimuli” • Detect physical/chemical changes in the environment • Often associated with the senses and movement • Smell • Touch • Taste • See • Hear Old, outdated list. “the classics” https://www.youtube.com/watch?v=8SI73-Ka51E

10. Characteristics of Life • “sense and respond to internal and environmental stimuli” • Some senses are different than in humans • Chemical signals • Ultraviolet and infrared light • Electrical and ultrasonic fields • Electromagnetic waves

11. Characteristics of Life “sense and respond to internal and environmental stimuli”

12. Characteristics of Life • “maintain homeostasis, regulate metabolism” • homeostasis • stable internal conditions • metabolism • sum of chemical reactions

13. Characteristics of Life • “maintain homeostasis, regulate metabolism” • ex. maintain body temperature • humans ~98.5°F • ex. Osmoregulation • water/salt balance

14. Characteristics of Life • Living things evolve and become betteradapted to their environment • Adaptations: Inherited characteristics that enhance an organism’s ability to survive in a particular environment • Evolution occurs at the population level • Characteristics of a group change over time • Individual organisms cannot evolve

15. Characteristics of Life • Living things evolve and become betteradapted to their environment • Descent with modification • all living things have a common ancestry • “Tree of Life” Vulpes ferrilata (Tibetan Fox) Vulpes vulpes (Red fox)

16. Vulpes ferrilata (Tibetan Fox) Vulpes vulpes (Red fox) Dusicyan australis (Falkland island wolf) Vulpes zerda (Fennec Fox) Cloonis pulchrum (Fantastic Mr. Fox) Martus mcflyus (Michael J. Fox) All of these creatures share common ancestry, but some share a more recent ancestor than others

19. Shared Characteristics of Life • are composed of cells • reproduce (using DNA) • grow and develop • sense and respond to the environment • maintain internal conditions (homeostasis) • evolve • take in energy/material from environment Is that it?

20. Shared Characteristics of Life • Take in energy from the environment • Some use the energy of sunlight • Capture* sun’s energy via photosynthesis • Convert sunlight to chemical energy and sugars • Some use energy from other living organisms • Consume plants or animals • *Energy is NOTmade, it is converted from one form to another, eventually becoming heat that is lost to space.

21. Shared Characteristics of Life • Science is about learning new things and making predictions about the natural world • therefore it is constantly changing / being refined • It is more important that you can support the your answer than recite a list • Learning Objective: Distinguish between living and nonliving things by describing the features that characterize living organisms

22. Shared Characteristics of Life • What about Viruses? • Contain DNA • Reproduce • Evolve • Not made of cells • only genetic material and protein • Homeostasis, reproduction, and energy collection depend on cells to do these functions

23. Levels of Organization

24. Hierarchical Organization

25. Energy transfer Allows hierarchical organization of life Organism Population Organ system Organ Community Tissue Bone cells Nucleus Cell Organelle Ecosystem Macromolecule Biosphere Oxygen atom Hydrogen atoms Molecule Water

26. Themes in Biology

27. Three Basic Themes of Biology • Energy transfer • Life requires continuous input of energy from the sun • Information transfer • Information must be transmitted within cells, among cells, among organisms, and from one generation to the next • Evolution • Evolution results in populations changing over time • Explains how the ancestry of organisms can be traced back to earlier forms of life