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Cells and Hereditary Unit A – Section 1 How do we define something that is living? - Section 1.1 The Cell Living things are different from nonliving things Trees, grass, moss, fish, frogs, birds, humans, etc.; they are all living things How do we define something that is living? We can describe it, but how do we define it? Organism Any individual form of life that uses energy to carry out its activities Do all organisms move? All organisms get water and other materials from the environment What are some other things that all living things have in common? - Characteristics of Life Living things have these characteristics: Organization The ability to develop and grow The ability to respond to the environment The ability to reproduce Needs of Life What do we need to live? - Organisms need: Energy – Almost all comes from the sun, includes food Materials – water, carbon dioxide, oxygen, etc. Living space – if you cannot grow, you will die If any of these are missing, the organism will die All Living Things Are Made Up of Cells!! Smallest unit of a living thing Unicellular Organism – an organism that is made up of a single cell Usually too small for you to see!! Can you name one? Multicellular Organism – an organism that is made up of more than one cell Many have complex bodies with parts that only do one thing: frog, human, penguin, etc. How Did We Discover the Cell? The Microscope!! - An instrument which make an object appear bigger than it is Robert Hooke gave the cell its name in the 1660’s when looking at a sample of cork (layer of bark taken from an oak tree) The sample looked like empty rooms or compartments which he gave the name “Cells” He was using a microscope that could magnify 30X (thirty times the actual size) Why did they look empty? The First Living Cells Observed Anton van Leeuwenhoek was one of the first people to describe living cells (1670’s) He looked at a drop of pond water under a microscope He was using a 300X lens and could see tiny Unicellular organisms swimming around!!! Let’s Talk Magnification How large would a penny be at 30X magnification? 300X? How large would a five foot tall human be at 30X magnification? 300X? - Magnification Cont. At 30X magnification, a penny would be the size of a bike tire! At 300X it would be so big that you need an Semi Truck to transport it! At 30X magnification, the person would be as tall as a 15 story building! At 300X, the person would be the size of Niagara Falls! Where Do Cells Come From? After these discoveries, people started to wonder if everything was made of cells… They continued to find cells in all living things but they all looked very different! This led to the question “Where do cells come from?” Finally, in the 1850’s, the question was answered: CELLS COME FROM OTHER CELLS The Cell Theory: 1. Every living thing is made of one or more cells 2. Cells carry out the functions needed to support life 3. Cells come only from living cells What is a Theory? We just talked about one example of a theory: The Cell Theory A Scientific Theory is a widely accepted explanation of things observed in nature Equally important, it must be supported by evidence including experimental evidence and observations Louis Pasteur In the 1800’s, he observed that inside soured milk was Bacteria… they did not have refrigeration like we have today so this was not uncommon He found that by using heat to kill bacteria, milk and other foods would stay fresh longer This is now called Pasteurization! He wondered if these microscopic organisms could be the cause of sickness in animals and humans too… Louis Pasteur’s Work Using a microscope (there is that instrument again) he found microorganisms everywhere he looked! He found bacteria in the blood of sick animals and humans, much like the soured milk His work led to the first animal vaccination for cholera and anthrax and treatment of rabies in humans, amongst others! Bacteria and Spontaneous Generation In the 1800’s, people thought that bacteria grew from nonliving materials… this was called Spontaneous Generation What does this sound like? He was then able to show that Spontaneous Generation does NOT happen! Pasteur’s Experiment
