Characteristics of Life

Biology = study of living things There is great diversity among living things All living things share certain characteristics

Cells All living things are made of cells Cell = smallest unit of structure and function for living things Some organisms are –Unicellular = made up of one cell –Multicellular = made up of many cells

Reproduction All living things are able to produce offspring Through this process, living things pass on their genetic traits

Genetic Code All living things have a universal genetic code The genetic code is based on DNA and its four nitrogen bases – A, T, C, and G

Growth / Development All living things grow / develop at some point during their lifetime. Growth = increase in size; usually occurs through mitosis (cell division) Development = changes; for instance, specialization of certain structures for certain jobs in an organism’s body

Metabolism All living things must obtain and use energy Metabolism = all of the reactions in an organism –Photosynthesis = process plants use to get energy from the sun –Cellular respiration = process used to break down food energy into cell energy (ATP)

Respond to Environment All living things are able to respond to things happening in and around them (stimuli) –Plants grow toward sunlight –People shiver when they are cold

Homeostasis All living things try to maintain a stable internal environment –Resting heart rate = beats per minute –Resting breathing rate = approx. 15 breaths per minute –Normal body temperature = 98.6 o F (37 o C)

Evolution = change in a species over time All living things, as a group, change over time –Populations evolve Population = members of the same species living in the same place at the same time –Individuals do NOT evolve