Characteristics of Life How would you determine whether something was alive or not?

What is Biology? Suffix: -logy – means “study of” Prefix: bio- – means “life” Other examples: – biography, antibiotic, biochemistry – meteorology, cosmetology, sociology

Life is characterized by 7 properties (themes of biology) Life is characterized by the presence of ALL of these properties at some stage in an organism’s life *movement is NOT a property of life – Clouds move – Water moves – Fans move

1. Cellular Structure & Function A cell is the smallest unit capable of all life functions Some organisms are unicellular Some organisms are multicellular Ex: Humans are multicellular – Your body is made up of over 100,000,000,000,000 cells!

2. Reproduction The process by which organisms make more of their own kind from one generation to the next Some organisms reproduce rapidly – Ex: bacteria divide every 15 minutes Some organisms reproduce slowly – Ex: elephants reproduce every 2 years Asexual vs. Sexual Reproduction

3. Metabolism The sum of all the chemical reactions carried out in an organism All living things need energy to grow, to move, and to process information. All energy is originally captured by the sun Plants and bacteria use the sun’s energy to grow Animals extract energy from the food they eat – Plants and other animals

Homeostasis The maintenance of stable internal conditions in spite of changes in the external environment Two types: – Positive feedback: enhances/accelerates the output Blood clots increase in a cut – Negative feedback: reduces the output

5. Heredity The passing of traits from parents to offspring A gene is the basic unit of heredity Genes are codes in your DNA Heredity is the reason children tend to look like their parents

6. Evolution Change in the inherited characteristics of species over generations Individuals with genetic traits that better enable them to meet nature’s challenges tend to survive and reproduce (natural selection)

7. Interdependence Ecology: study of the interactions of organisms with one another and with the nonliving part of their environment Organisms are dependent on one another and their environment