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Unformatted text preview: Characteristics of Life: Biology= the study of atoms molecules LIFE
A. Hierarchy of Organization organelles *cells tissues organs But what exactly IS life???
Above the organism level: populations àcommunities à ecosystems à biosphere organ systems organisms ß At each step up in organization, new properties emerge (emergent properties) B. Cells are the basic unit of structure and function C. Reproduction: Life is continued through heritable information (DNA, RNA); life comes from life
(no spontaneous generation) Prokaryotic and Eukaryotic Cells - share similar basic design - approx. 70% wate r, 15% protein - use DNA to reproduce •Prokaryotes= one way transfer of DNA from donor to recipient •Eukaryotes= DNA from two individuals combines to make third individual; new combinations possible Prior to reproduction, DNA is copied by the cell: 1 D. Take in, use, and transform energy - metabolism: chemical reactions involved in converting energy from environment and using it in processes essential to growth, repair, and reproduction -use ATP (adenosine triphosphate) as source of all immediate energy E. Organisms interact with their environment; respond to stimuli
Ex: Cellular responses to changes in sugar le vels, etc. in body Nervous and hormonal (endocrine) responses Plant tropisms (response to wate r, gravity, light, touch, etc) Homeostasis=maintain constant internal environment, regardless of changing external environment G. Adaptation and evolution F. Growth and Development
-irreversible; number of cells, form, function of cells may change Evolution (change over time) is a core theme of biology, and the main unifying concept of all life -variation of individuals leads to natural selection which leads to evolution -adaptations may be structural, physiological, and/or behavioral H. Movement: basic property of cells -amoeboid motion, cilia, flagella -muscular systems I. Water
All living things require wate r– inside all cells, surrounds all cells -helps maintain stable body temperature -transports mate rials 2 ...
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This note was uploaded on 02/22/2010 for the course BIO 181 taught by Professor Milton during the Fall '08 term at N.C. State.
- Fall '08