What is life?

Characteristics of Living Things. Mr. Hanczyc

8 Characteristics of Living Things 1. Composed of cells 2. Respond to external stimuli 3. Obtain and use energy 4. Grow and develop 5. Reproduce 6. Maintain stable internal environment 7. Change over time: Adapt and evolve 8. Based on a universal genetic code

1. Composed of cells  Organisms are composed of one or more cells  Cells are the basic unit of life – they can grow, respond to stimuli, and reproduce

2. Respond to external stimuli  Organisms detect and respond to stimuli from their environment  Stimulus – a signal to which an organism responds

3. Obtain and use energy  All organisms must take in energy to grow, develop, and reproduce.  Metabolism - combination of chemical reactions that release energy in food.  Endocytosis – a process that cells use to absorb substances by engulfing

3. Obtain and use energy  Endocytosis (ex. amoeba vs. paramecia)

4. Grow and develop  Every organism has a pattern of growth and development.  Humans - A single fertilized egg divides again and again into multiple cells.  Cells differentiate to form specialized cells ex. muscle cells, neurons, blood cells

4. Grow and develop

5. Reproduce  All organisms reproduce to form similar organisms.  asexual reproduction – single organism divides to produce identical new organisms  sexual reproduction – cells from two organisms unite to form the first cell of a new organism

5. Reproduce 5,000,000,000,000,000,000,000

6. Maintain a stable internal environment  Homeostasis – process by which organisms keep their internal environment stable, even when external conditions change rapidly.  ex. constant body temperature in humans

7. Change: Adapt and Evolve  Adaptations are traits that provide an advantage for organisms in a certain environment.  Organisms adapt to their environment as species through natural selection.  Evolutionary change occurs on the population level and links organisms to a common ancestor 3.5 BYA.

8. Universal Genetic Code  Offspring inherit traits from their parents.  DNA / RNA provide mechanism of inheritance.  Asexual Reproduction – identical offspring  Sexual Reproduction – genetic variation

8. Universal Genetic Code

References  PA Standards – 3.1.B.A1,  Miller and Levine. Biology. pp  Amoeba Videohttps:// jNhj07qa-Ahttps:// jNhj07qa-A  Sensitive Plant Video  Acorn Video  Bacteria Growth Video