Transcript Cells
Resources: 7.1 Study Workbook www.worldofteaching.com http://www.ducksters.com/science/the_cell.php 7.1 Life Is Cellular Lesson Objectives State the cell theory. Describe how the different types of microscopes work. Distinguish between prokaryotes and eukaryotes. 7.1 Concept Map Hooke Leeuwenhoek Shleiden early studies by: compound light microscope 1 cells transmission & scanning electron microscopes Schwann Virchow contain hereditary material: are surrounded by a 2 cell membrane are summarized by the 3 cell theory states stains Word Bank: cell theory DNA cell membrane prokaryote eukaryote cell 4 DNA in a nucleus 5 eukaryote plant animal, fungi, protists no nucleus 6 prokaryote bacteria 1. All living things are made of cells 2. Cells are the basic unit of structure & function of living things 3. All cells come from pre-existing cells Videos: • Cell History (2:43) by Teacher's Pet • TedEd – The Wacky History of the Cell Theory (6:12) Some Random Cell Facts The average human being is composed of around 100 Trillion individual cells. Humans actually carry more bacteria cells than human cells. It would take as many as 50 cells to cover the area of a dot on the letter “i” Lesson Summary The Discovery of the Cell The invention of the microscope in the 1600s enabled researchers to see cells for the first time. • Robert Hooke named the empty chambers he observed in cork “cells.” • Anton van Leeuwenhoek was the first to observe living microorganisms. • Cells are the basic units of life. • Discoveries by German scientists Schleiden, Schwann, and Virchow led to the development of the cell theory, which states: a) b) c) All living things are made of cells. Cells are the basic units of structure and function in living things. New cells are produced from existing cells. Notes: http://science.howstuffworks.com/innovation/scientific-method4.htm The Cell Theory Discovery of Cells 1665- English Scientist, Robert Hooke, discovered cells while looking at a thin slice of cork. He described the cells as tiny boxes or a honeycomb He thought that cells only existed in plants and fungi Anton van Leuwenhoek 1673- Used a handmade microscope to observe pond scum & discovered single-celled organisms He called them “animalcules” He also observed blood cells from fish, birds, frogs, dogs, and humans Therefore, it was known that cells are found in animals as well as plants 150-200 Year Gap Between the Hooke/Leuwenhoek discoveries and the mid 19th century, very little cell advancements were made. This is probably due to the widely accepted, traditional belief in Spontaneous Generation. -Mice from dirty clothes/corn husks -Maggots from rotting meat 19th Century Advancement Much doubt existed around Spontaneous Generation Conclusively disproved by Lazzaro Spallanzani & Louis Pasteur Ummm, I don’t think so! Robert Brown botanist named the cell nucleus and proposed its importance in cell formation Development of Cell Theory 1838- German Botanist, Matthias Schleiden, concluded that all plant parts are made of cells 1839- German physiologist, Theodor Schwann, who was a close friend of Schleiden, stated that all animal tissues are composed of cells. Development of Cell Theory 1858- Rudolf Virchow, German physician, after extensive study of cellular pathology, concluded that cells must arise from preexisting cells. The Cell Theory Complete The 3 Basic Components of the Cell Theory were now complete: 1. All organisms are composed of one or more cells. (Schleiden & Schwann)(1838-39) 2. The cell is the basic unit of life in all living things. (Schleiden & Schwann)(1838-39) 3. All cells are produced by the division of preexisting cells. (Virchow)(1858) Modern Cell Theory Modern Cell Theory contains statements, in addition to the original Cell Theory: The cell contains hereditary information(DNA) which is passed on from cell to cell during cell division. All cells are basically the same in chemical composition and metabolic activities. All basic chemical & physiological functions are carried out inside the cells.(movement, digestion, etc) Cell activity depends on the activities of sub-cellular structures within the cell (organelles, nucleus, plasma membrane) Energy flow (metabolism and biochemistry) occurs within cells Why is the cell theory so important? • Cell theory is really important because it provided, and still provides one of the great unifying theories in biology: one that says in spite of all the vast diversity of organisms, they are united at a very fundamental level, namely the presence of cells. How Has The Cell Theory Been Used? Disease/Health/Medical Research and Cures (AIDS, Cancer, Vaccines, Cloning, Stem Cell Research, etc.) Some Parting Thoughts It is amazing to think that the cells that make up our bodies are just as alive as we are. Humans are just an intricately designed community of cells, which must work together to survive. Lesson Summary Exploring the Cell Scientists use light microscopes and electron microscopes to explore the structure of cells. • Compound light microscopes have lenses that focus light. They magnify objects by up to 1000 times. Chemical stains and fluorescent dyes make cell structures easier to see. • Electron microscopes use beams of electrons focused by magnetic fields. They offer much higher resolution than light microscopes. There are two main types of electron microscopes—transmission and scanning. Scientists use computers to add color to electron micrographs, which are photos of objects seen through a microscope. Lesson Summary Prokaryotes and Eukaryotes Cells come in an amazing variety of shapes and sizes, but all cells contain DNA. Also, all cells are surrounded by a thin flexible barrier called a cell membrane. There are two basic categories of cells based on whether they contain a nucleus. The nucleus (plural: nuclei) is a large membrane-enclosed structure that contains DNA. • Eukaryotes are cells that enclose their DNA in nuclei. • Prokaryotes are cells that do not enclose their DNA in nuclei.