Biology Notes Chapter 1Levels of Organization Molecule- Two or more atoms joined in chemical bonds. Cell- Smallest unit that can live and reproduce.Emergent Properties Each level of organization in nature is emergent. The properties of an emergent cell are a system that does not appear in any of its component parts.1.1 Key concepts We study the world of life at different levels of organization, which extend from atoms and molecules to the biosphere. The quality of life emerges at the level of cells. Elan Vital- is a light force1.2 Overview All living things have similar characteristics. Continual inputs of energy and the cycling of materials maintained in lifes complex organization. Organisms sense and respond to change DNA inherited from parents is the basis of growth and reproduction in all organisms.Energy and lifes organization Energy- the ability to do work Nutrients- atoms or molecules essential in growth and survival that an organism cannot make for itself.

Producers and consumers Producers- acquires energy and raw materials from the environment. (They also make their own food photosynthesis) Consumers- cannot make their own food (Homeostasis) Organisms use receptors to help keep conditions in their internal environment within ranges that their cells can tolerate. Organisms grow, develop, and reproduce using information in their DNA, A nucleic acid inherited from their parents. Information encoded in DNA is the source of an individuals distinct features (traits). 20 amino acids are the building blocks used to build a great variety of proteins. All organisms consist of one or more cells, which stay alive through ongoing inputs of energy and raw materials. All sense and respond to change; all inherited DNA, a type of molecule that encodes information necessary for growth, development, and reproduction. Schleiden and Schwann came up with what is known as "The Theory of Cells" or "Cell Theory." The main principles of "Cell Theory" are: 1. All living things are made up of cells. 2. Cells are the smallest units of living things 3. Cells only rise from existing cells. Of an estimated 100 billion kinds of organisms that have ever lived on earth, as many as 100 million are with us today. A theory of evolution by natural selection is an explanation of lifes diversity. Origin of species- Natural Selection Information encoded in DNA is the basis of traits an organism shares with others of its species. Mutation is the original source of variation in traits. Radiation/ chemicals cause mutation. Some forms of traits are more adaptive than others, so their bearers are more likely to survive and reproduce. Over generations, adaptive traits tend to become more common in a population; less adaptive forms of traits become less common and are lost. Evolution is change in a line of descent. (traits that characterize a species can change over generations of evolving populations.) Natural selection- is an evolutionary process with differential survival and reproduction among individuals that vary in the details of their shared, heritable traits.