Lecture #2 Characteristics of Life Studying Life What Characteristics do all living things share?

Living or nonliving? Nonliving things share some characteristics with living things, but not all. To be considered living, an object MUST have ALL (8) characteristics of life met.

1. Cellular Organization All living things are made of one or more cells. Cell - Smallest unit that is capable of all life functions. Onion Cell Red Blood Cells

Though small – cells are complex and highly organized

2. Universal Genetic Code DNA & RNA Living things are able to pass on their traits to their offspring through genes that are passed from parent to offspring each generation.

The genetic code within DNA is the same in all living things

3. Growth & Development From a fertilized egg, organisms change –Growth –Cell specialization Even single cell organisms change over time

Another example of Growth and Development Redwood Cone & SeedsRedwood Tree!

4. Responsiveness Living things respond to their environment Bird MigrationHibernating Bear and Cubs

Example- Seeds can be planted and will grow under right conditions Example- Some bacterial spores can be dormant for hundreds of years and still germinate under the right conditions Culturable bacteria have been isolated from ice core samples

5. Reproduction Living organisms have the ability to reproduce; or to make more of their own kind. Puff Ball MushroomCrocodile Hatching

Two Types of Reproduction Asexual - Single organism creates clone of self

Sexual –Cells from two parents unite to form first cell of new organism –Offspring is different from parents

6. Homeostasis Living organisms maintain stable internal conditions in order to function properly. They do this despite changes in the external environment.

The body can only perform functions within a certain range of conditions –Temperature –Sugar levels –Ph levels Despite external conditions – organisms maintain homeostasis This costs energy

7. Groups of living things Evolve Spontaneous mutations occur in DNA If a mutation is advantageous it is passed on to offspring

Over time (many generations) a species will have a collection of advantageous mutations Can you think of some of the adaptations shown in the arctic fox?

Change over time = evolution The diversity of life that we see today is a result of a long history of change.

8. Metabolism Living things obtain and use material and energy. How do organisms get energy?

Some organisms make their own food (photosynthesis/chemosynthesis); some organisms consume other organisms What kind of processes use energy?

Reproduction Homeostasis Growth (and plenty more)

Metabolism is defined as the combination of chemical reactions through which an organism builds up or breaks down materials.

Interdependence The interdependence seen within biological communities is a result of a long history of evolutionary adjustments.

The complex web of interactions in a biological community is disrupted when the community is polluted, a species becomes extinct, or when other human caused or natural environmental changes occur.

Think about it: Viruses are pathogens (disease causing agents) that plague every kingdom of life. They cause disease. Viruses use their hosts cellular machinery to make additional copies of themselves. Based on what you now know, do you think they are considered living things? Why or why not? Discuss this with your shoulder partner and be prepared to report out.

Take 2 minutes to summarize what you have learned about what it means to be a ‘living’ thing. Share with your shoulder partner to check for understanding.