Cell Biology - Cell PDF

 The Discovery of the Cell Significant Landmarks Cell Theory Overview Cell Diversity Basic properties of cell  The cell is the smallest unit of life. All living things are made of cells The Cell: The basic...

 The Discovery of the Cell Significant Landmarks Cell Theory Overview Cell Diversity Basic properties of cell  The cell is the smallest unit of life. All living things are made of cells The Cell: The basic structural and The Cell? functional unit of a living organism. Cell Biology: The study of cells and their structure, function, and behavior  Significant Landmarks 1667- Dutch Antonie van Leeuwenhoek first observed living cells He is commonly known as "the Father of Microbiology", and one of the first microscopists and microbiologists Using single-lensed microscopes of his own design and make, van Leeuwenhoek was the first to observe and experiment with microbes He was the first to observe bacteria and protozoa. He termed them “animalcules,” or little animals  https://www.youtube.com/watch?v=y4B3kl9Rvrs&t=2s A 1795 illustration of van Leeuwenhoek's animalcules by an unknown artist Significant Landmarks cont... In 1833-Robert Brown discovered the nucleus Brown first observed the nucleus within cells taken from orchid tissues He recognized and described the existence of the cell nucleus and stomata (breathing pores that act as gateways, to exchange gases with the atmosphere)  In 1838, German Botanist Matthias Schleiden stated that all plants are aggregates of independent and separate cells In 1839, German Zoologist Theodor Schwann reported that all animal tissues consist of individual cells Significant Landmarks In 1855, German Pathologist, Rudolf Virchow stated that just as animals are unable to arise without previously existing animals, cells are unable to arise without previously existing cells  Cell Theory Credit for developing cell theory is usually given to two scientists: Theodor Schwann and Matthias Jakob Schleiden While Rudolf Virchow contributed to the theory, he is not as credited for his attributions to it The cell theory includes the following three principles 1. All living organisms are made up of one or more cells 2. The cell is the basic structural and functional unit of life 3. All cells come from pre-existing cells through division Botanist Matthias Schleiden stated that all plants are Max Knoll and Ernst Ruska invented the electron aggregates of independent and separate cells microscope 1838 1839 1931 1974 Theodor Schwann reported that all animal tissues Albert Claude, Christian de Duve, and George E. consist of individual cells Palade studied the structural and functional organization of the cell Significant Landmarks Cell Diversity Cells are small, membrane-enclosed units filled with a concentrated aqueous solution of chemicals and have the capacity to create copies of themselves by growing and then dividing In the hierarchy of biological organization, the cell is the simplest collection of matter that can be alive  Organisms Unicellular Multicellular (Organisms that have only one (Organisms that have more than cell) one cell) Ex: Amoeba Ex: Some Fungi and Algae Paramecium Plants Bacteria Animals  Fundamentally cells are similar Ex: using energy, responding to the external environment, and reproducing Different cells come in a variety of sizes and shapes Why cells are small ? ✓ To facilitate efficient diffusion of substances (Nutrients, Waste products etc.) in and out of cells ✓ The rate of diffusion is affected by; Surface area available for diffusion Temperature The concentration gradient of diffusing substance The distance over which diffusion must occur  Why cells are small ? An increased surface area to volume ratio Increased exposure to the environment Nutrients and gases can move in and out of a small cell through cell membrane more easily than a larger cell As a cell’s size increases, its volume increases much more rapidly than its surface area. Therefore, not enough material will be able to cross the membrane fast enough to accommodate the increased cellular volume. At the end, a cell may die. Thus, many organisms are made up of many small cells, instead of a few large cells. If the cells are large, they need to have other adaptive mechanisms for efficient functioning. Basic Properties of Cell Cells are highly complexed and organized The plasma membrane encloses a cell and separates its contents from its surroundings. A semifluid matrix called the cytoplasm fills the interior of the cell contains the chemicals: sugars, amino acids, and proteins as well as organelles. Organisms are built and functioning according to information encoded in a collection of genes, which are constructed of genetic material. Basic Properties of Cell Cells are capable of reproducing Cell division is a process in which the contents of a “mother” cell are distributed into two “daughter” cells. Prior to division, the genetic material is duplicated, and each daughter cell receives a complete and equal share of genetic information. Basic Properties of Cell Cells acquire and utilize energy Every biological process requires the input of energy utilized in the form of electromagnetic radiation from the sun. The energy of light is trapped by light-absorbing pigments present in the membranes of photosynthetic cells (Mainly in plants) and converted into chemical energy by photosynthesis. Chemical energy is stored in the form of carbohydrates such as sucrose or starch in plants. Animals consume these carbohydrates as well as humans broken down it into component glucose molecules which released by the liver and circulates through the body and deliver chemical energy to all the cells. In a cell, glucose is disassembled in such a way that its energy content can be stored in a readily available form (usually as ATP). ATP utilized for energy-requiring activities in the cell. Basic Properties of Cell Cells carry out a variety of chemical reactions Cells function like miniaturized chemical plants. Even the simplest bacterial cell is capable of hundreds of different chemical transformations. Virtually all chemical changes that take place in cells require enzymes which are molecules increase the rate of chemical reactions. The sum of the chemical reactions in a cell represents that cell’s metabolism.  Questions........ 1.Give a definition for cell. 2.What are the main principles included in the cell theory? Give the names of the scientists who have contributed to the cell theory. 3.Cell shapes have evolved according to their functions. Give three examples to prove this statement. 4.Organisms comprise many small cells, not a few large ones. Why? 5.List out the basic properties of a cell. Thank You