Relative sizes: 1. molecules (1nm). 2. cell membrane thickness (10nm). 3. virus (100nm). 4. bacteria (1um). 5. organelles (less 10um). 6. cells (<100 um). 7. generally plant cells are larger than animal cells. nm= nanometer (10 -9 m) um= micrometer (10 -6 m)

The Cell Theory All organisms are made of 1 or more cells. The cell is the smallest unit of life. Cells come from pre-existing cells.

Cell Scientist 1600s Dutch tradesman and scientist Antony van Leeuwenhoek. Credited with developing some of the first microscopes powerful enough to observe microorganisms ( x). He made detailed observations of microorganisms in water, dental plaque, and other substances. English scientist Robert Hooke. First used the word “cell” to refer to the tiny compartments in living things. Observed slices of cork under a microscope and saw tiny compartments, which reminded him of the rooms or cells in a monastery German botanist Matthias Schleiden. Observed plant tissues under the microscope and concluded that all plants are made of large numbers of organized cells German zoologist Theodor Schwann. Observed animal tissues under the microscope and concluded that all animals are made of large numbers of organized cells.

Part of the Cell Theory Evidence Many organisms have been examined and found to consist of cells. The tissues of multicellular organisms have been found to consist of cells. *One exception: connective tissue. Connective tissue contains a greater volume of extracellular material than cells. For example: bone, a type of connective tissue, is composed of a relatively small number of cells, called osteoblasts, which secrete a large volume of collagen and calcium-rich substance. This substance hardens into “bone.” Cells taken from multicellular organisms often survive and function for a time, whereas individual parts of cells do not. The first cells were thought to have arisen from non-living material, however there is experimental evidence that cells today cannot develop spontaneously from non-living material—they can only arise from pre-existing cells. Ex: Louis Pasteur’s experiment (1859) “He boiled meat broth in a flask, heated the neck of the flask in a flame until it became pliable, and bent it into the shape of an S. Air could enter the flask, but airborne microorganisms could not - they would settle by gravity in the neck. As Pasteur had expected, no microorganisms grew. When Pasteur tilted the flask so that the broth reached the lowest point in the neck, where any airborne particles would have settled, the broth rapidly became cloudy with life. Pasteur had both refuted the theory of spontaneous generation and convincingly demonstrated that microorganisms are everywhere - even in the air.”

These organisms are able to carry out all the processes which are characteristic of living things such as: a. metabolism which includes respiration the synthesis of ATP. b. response to a change in the environment c. homeostasis the maintenance and regulation of internal cell conditions. d. growth which for a unicellular organism means an increase in cell size and volume. e. reproduction which for the unicellular organism is largely asexual through cell division to form a clone. f. nutrition which means either the synthesis of organic molecules or the absorption of organic matter. Functions of Life

Examples: 1.Atoms (parts) join to form molecules (whole). Individual atoms H and O do not have the properties of water molecules. The properties of water molecules are emergent properties that result from the interaction of H and O atoms. 2. Molecules (parts) join to form cells (whole). Individual lipid, protein, carbohydrate, nucleic acid, and water molecules do not have the properties of cells. The properties of cells are emergent properties that result from the interaction of different molecules. Properties that result from the interaction between the parts of a whole. Emergent properties do not belong to the individual parts—they belong to the whole. Emergent Properties

Bone Marrow Transplantation: An Established Stem Cell Therapy Used to treat people with blood diseases. For example, certain types of leukemia (bone marrow cancer) can be treated with bone marrow transplantation. 1.Blood rich in hematopoietic stem cells (stem cells that can differentiate in to bone marrow and blood cells) is harvested from a donated umbilical cord. 2.The patient is given chemotherapy drugs to destroy his/her bone marrow cells, including the cancerous bone marrow cells. 3.The patient receives a transfusion of umbilical cord blood (the blood type of the donor and patient must be compatible). 4.The hematopoietic stem cells go to the patient ’ s bone marrow and produce new, healthy bone marrow cells. Stem Cell Therapy