Introduction to Cells PDF

Chapter 1 Introduction to cell Dr. Azi Azeyanty Bt Jamaludin 01 Diversity and unity of cells 02 Cellular Organization 03 Cell Theory 04 Cells under microscope 05 History of cell discovery  Introduction Biology is a branch of science that is concerned with the study...

Chapter 1 Introduction to cell Dr. Azi Azeyanty Bt Jamaludin 01 Diversity and unity of cells 02 Cellular Organization 03 Cell Theory 04 Cells under microscope 05 History of cell discovery  Introduction Biology is a branch of science that is concerned with the study on life and living organisms. Because life is so diverse, it is helpful to have a system that groups organisms into categories. Two areas of biology help us group organisms into categories: ○ Taxonomy is the discipline of identifying and naming organisms according to certain rules, and ○ Systematics makes sense out of the bewildering variety of life on Earth by classifying organisms according to their presumed evolutionary relationships. 01: The Diversity and Unity of Cells Cells are the fundamental units of all living things. Cells are the smallest units of life differ in size, shape & functions. Although the diversity organisms is incredible, the cells of all organism share many similarities. Only a few structural differences between most types of cells, because of some organisms are single cells. 02: Cellular Organization The characteristics of life: All living organisms share the following characteristics of life: i. Organization: the levels of biological organization. ii. Metabolism/Energy Use: Acquisition of materials and energy from the environment. iii. Maintenance of Internal Constancy/Homeostasis iv. Reproduction, Growth and Development: Production of offspring. v. Evolution: Adaptations to a changing environment Organization Metabolism/Energy Use Maintenance of Internal Constancy/Homeostasis Reproduction, Growth and Development Evolution  03: Cell Theory All organisms are composed of one or more cells. Cells are the basic living unit of structure and function in organisms. All cells come only from other cells. Four generalizations constitute the cell theory: Every living organism consists of one or more cells A cell is the smallest unit of life, individually alive even as part of a multicelled organism All living cells come from division of preexisting cells Cells contain hereditary material, which they pass to their offspring during division  Size of Cell Cell size varies but are quite small. A frog’s egg is about 1 millimeter (1mm) in diameter. Large enough to be seen by naked eye. Most cells are smaller than 1mm. Some cells are as small as 1 micrometer (1μm). Microscopes permit extremely small objects to be seen, objects measured in the metric system in micrometers and nanometers. A micrometer (μm) is equivalent to a millionth of a meter, while a nanometer (nm) is a billionth of a meter.  Why are cells so small? Cells being small is an advantage for multicellular organisms: Nutrients such as glucose can enter the cell. Wastes such as CO2 can exit cell. Therefore, surface area affects the ability to get materials in and out of a cell. As cells increase in volume, the proportionate amount of surface area decreases. For a cube-shaped cell: The volume increases by the cube of the sides (height X width X depth). The surface area increases the square of the sides and the number of sides (height X width X 6). If a cell doubles in size, its surface area increases fourfold, while the volume increases eightfold.  04: Cells under microscope How scientist study cells? Microscopy is the study of the principle how microscope operate and the methods of using them. Most cells are far too small to see with the naked eye. We use different types of microscopes and techniques to reveal cells and their internal and external details. Our bodies are comprised of several hundred different types of cells, with billions of each cell type present. Each type of cell is specialized in its particular function. Why are microscope needed to see most cells? Cells are so small that a microscope is needed to see them.  Microscope are divided into LM & EM Light microscopes Electron microscopes Compound microscope Transmission electron Microscopes (TEM) Phase-contrast microscope Scanning electron microscopes (SEM) Fluorescence microscope Phase‐Contrast Microscope This microscope also contains special condensers that throw light “out of phase” and cause it to pass through the object at different speeds. Live, unstained organisms are seen clearly with this microscope, and internal cell parts such as mitochondria, lysosomes, and the Golgi body can be seen with this instrument. The Fluorescent Microscope Uses ultraviolet light as its light source. When ultraviolet light hits an object, it excites the electrons of the object, and they give off light in various shades of color. Since ultraviolet light is used, the resolution of the object increases. A laboratory technique called the fluorescent‐antibody technique employs fluorescent dyes and antibodies to help identify unknown bacteria. Transmission Electron Microscope (TEM) ⚫ The more traditional form of electron microscope. ⚫ To use this instrument, one places ultrathin slices of microorganisms or viruses on a wire grid and then stains them with gold or palladium before viewing. ⚫ The densely coated parts of the specimen deflect the electron beam, and both dark and light areas show up on the image. Scanning Electron Microscope (SEM) The more contemporary form electron microscope. This microscope gives lower magnifications than the TEM. The SEM permits three‐dimensional views of microorganisms and other objects. Whole objects are used, and gold or palladium staining is employed. History of cell discovery Antoni Van Leeuwenhoek Dutchman who selling buttons & clothes AND YET have a remarkable ability and hobby of developing high quality microscope 1665: Antoni van Leeuwenhoek first observed “many very small animalcules” Father of microscopy and microbiology Improvement of microscope Robert Hooke Architect and philosopher Magnified a piece of thinly sliced cork and named the tiny compartments he observed “cellae” Robert Brown Scottish Botanist and paleobotanist First to identify a cell nucleus Much of his work on plants Matthias Schleiden A lawyer who don’t want to be one! Preference in BOTANY! Hypothesized that a plant cell is an independent living unit even when it is part of a plant Theodor Schwann German Physiologist Co-Founder of Cell Theory along with Schleiden Concluded that the tissues of animals as well as plants are composed of cells Schwann cells in peripherous nervous system