CELL IS BASIC UNIT OF LIVING THINGS Living Things are different from nonliving things: they have CHARACTERISTICS & NEEDS All living things are made of Cells Microscope led to discovery of Cells Cells come from other Cells CELL THEORY is important to study of BIOLOGY

CHARACTERISTICS OF LIVING THINGS Living things have these characteristics: –Organization ( body must be organized to help it meet its needs) –Ability to develop & grow –Ability to respond to the environment –Ability to reproduce

NEEDS OF LIVING THINGS Organisms need energy, material & living space. All organisms need a steady supply of ENERGY to stay alive. –Most all forms of life use energy originally from the Sun. Some, like plants & bacteria, can capture the Sun’s energy to store it in food. The food animals eat comes from plants or other organisms (that eat plants) MATERIALS: Some comes from food for growth & reproduction. Some from Nitrogen, Oxygen, Carbon Dioxide & Water. LIVING SPACE: Need space to live & grow. If any one of these requirements is missing, an organism will die.

ALL LIVING THINGS ARE MADE OF CELLS Cell is smallest unit of living thing. One celled organisms are UNICELLULAR. If made of many cells: MULTICELLULAR Needs & characteristics of single celled organisms are the same as for multicellular. In multicellular, many different types of cells work together to carry out basic activities of life.

MICROSCOPE LED TO DISCOVERY OF CELLS Microscope = instrument which makes an object appear bigger than it is. In 1660’s, Robert Hooke used a microscope to look at many materials. While looking at dead cork cells (from oak bark) he saw tiny, empty chambers or “cells”. He came up with the term CELL. In 1670’s ANTON van LEEUWENHOEK looked at actual living cells in blood, teeth scrapings and rainwater.

Cells Come From Other Cells By 1850’s, scientists saw cells actually dividing. Observations and evidence gathered over many years by scientists became summarized in 3 concepts of CELL THEORY: Every living thing is made of 1 or more cells. Cells carry out the functions needed to support life. Cells come only form other living Cells

CELL THEORY IS IMPORTANT TO STUDY OF BIOLGOY French Scientist, Louis Pasteur showed how microscopic organisms caused food spoilage & disease. Found way to heat milk to kill bacteria, that he knew spoiled milk. Using a microscope, Pasteur found microorganisms everywhere (air, water, & soil) Pasteur did an experiment (with boiling broth) showing bacteria are present in air & don’t grow spontaneously.