2. Biology…What is it? Biology is the study of life. SO….What does it mean to be living?

3. Characteristics of Life To be considered living, an organism must….. 1. Be based on a universal genetic code. –DNA 2. Grow and develop

4. Characteristics of Life 4. Nutrition: To obtain materials to use for building blocks and energy. 3. Be able to R eproduce -Asexually -Sexually

5. 5.Excretion: Producing and releasing waste materials. 5.Metabolism: all chemical reactions. -Digestion and synthesis Characteristics of Life

6. 7. Be able to sense and respond to their environment -stimulusresponse  Humans:  Plants:

7. Characteristics of Life 8. Maintain stable internal environment -Homeostasis

8. Characteristics of Life 9. Change over time, as a group. -Evolution 10. Made of units called Cells -Unicellular -Multicellular

9. Levels of Organization LevelFunctionExample OrganismSingle living thing Organ SystemDifferent organs function together OrganDifferent tissues function together TissuesSimilar cells function together CellsSmallest unit of life Molecules Smallest unit of a substance with the same properties AtomSmallest unit of matter Nervous System Brain Nervous Tissue Nerve Cell Protein Carbon Human

10. Viruses…Living or not?  Now that we know what makes something living, let’s look at a virus. Viruses come in many different shapes and they cause many different diseases but, they all have something in common….

11. Viruses and Living Cells CharacteristicVirusCell StructureGenetic material surrounded by a protein capsid Cell membrane, cytoplasm; genetic material, ribosomes ReproductionOnly within a host cellYes, sexually and asexually Genetic CodeDNA or RNADNA Growth and Development NoYes MetabolismNoYes Sense and Respond NoYes EvolveYes HomeostasisNoYes

12. Life Cycle of a virus Lytic Cycle

13. Life Cycle of a virus Lysogenic cycle

15. What about viruses? https://www.youtube.com/watch?v =PHp6iYDi9ko https://www.youtube.com/watch?v =Rpj0emEGShQ