Characteristics of Life Section 1-2

Objectives  List six characteristics of Life (GROUCH)  Describe how a living thing is organized

What does it mean to be alive?  All organisms share certain features that are characteristic of all living things.  Growth  Reproduction  Organization  Use Energy  Cells  Homeostasis

Growth All living things grow Nonliving things grow by accumulating more of the material they are made of Living things grow by cell enlargement and cell division (two new cells from 1 existing cell) Development– produced by repeated cell divisions and cell differentiation Example – 1 fertilized egg divides into 50 trillion cells in an adult!

Reproduction All species of organisms reproduce Reproduction is essential to the survival of a species, but not an individual organism Single celled organisms simply divide and make two copies (asexual) Sexual reproduction combines genetic information of two organisms to produce unique offspring

Organization Living things are highly organized They take in substances from the environment and organize them Inside cells specific structures carry out particular functions In multicellular organisms cells are grouped by their function

Use Energy All living things use energy Metabolism = sum of all chemical processes that occur in an organism Require energy to: Maintain molecular and cellular organization Grow reproduce

Cells All living things are made of cells Cells are the basic unit of life Cells are always very small Larger organism = more cells (not bigger cells) Human Cheek Cells Euglena

Homeostasis HOmie-oh-STAY-sis All living things maintain stable internal conditions Cells control their water content Multicellular can control: Temperature Oxygen/Carbon Dioxide Levels pH of blood (acidity or alkalinity) Water content (plants) Shivering Sweating Pumping Water!