Biology Notes PDF

The Cell The Cell - The smallest functional unit of life. - The basic building blocks of all organisms. - All processes that sustain life. Processes of Cell Division: Mitosis produces two genetically identical daughter cells from a single parent cell. For growth, tissue repair, an...

The Cell The Cell - The smallest functional unit of life. - The basic building blocks of all organisms. - All processes that sustain life. Processes of Cell Division: Mitosis produces two genetically identical daughter cells from a single parent cell. For growth, tissue repair, and asexual reproduction. (It occurs when there is a damaged or injured cell needing replacement). Meiosis produces gametes (sperm and egg cells in animals, and spores in plants and fungi). It results in four non-identical daughter cells, each with half the number of chromosomes of the parent cell (haploid daughter cells). This process is crucial for sexual reproduction and genetic diversity. All living things are made up of one or more cells. Prokaryotic Cells / Unicellular Organisms / Microscopic - made up of one cell only. Ex. Bacteria, Protozoa, and Archaea. They do not have a nucleus and other membrane- bound organelles. Eukaryotic Cells / Multicellular Organisms / Macroscopic - made up of many cells. Ex. Plants, Animals, and Fungi. They have a nucleus and other membrane-bound organelles. CELL Why do you think the cell is considered as the basic unit of life? Cells are considered the basic unit of life because they are the smallest structures capable of performing all the functions necessary for life. Structural Organization: Cells are the smallest units that exhibit all the characteristics of life. They have organized structures and internal components (organelles) that perform specific functions. Some functions of cells are: 1. Energy production 2. Protein synthesis 3. Waste removal Functional Independence: Each cell can carry out essential life processes independently. Cell processes include: 1. Metabolism (the chemical reactions that provide energy and build cellular structures) 2. Homeostasis (maintaining a stable internal environment) 3. Reproduction Genetic Information: Cells contain genetic material (DNA) that guides the development, functioning, and reproduction of the organism. This genetic code is fundamental for heredity and for the transmission of traits from one generation to the next. Ex. Dominant Traits - Attached Earlobe Recessive Traits - Free Earlobe Reproduction: Cells can reproduce on their own through processes like mitosis and meiosis, allowing for growth, repair, and the continuation of life. Response to Stimuli: Cells can respond to environmental changes and stimuli, which is essential for survival. This includes adapting to changes, communicating with other cells, and maintaining equilibrium. Additional Notes: ❖ DNA is found in the Nucleus. ❖ DNA - Deoxyribonucleic Acid ❖ RNA - Ribonucleic Acid The Microscope is an instrument used to view objects that cannot be seen by an unaided eye. It can magnify the size of small objects. The Invention of the Microscope and Discovery of the Cell LENS derived from the Latin word lentil, because it closely resembled the shape of the lentil bean. These lenses were not fully utilized until the 13th century, when they were finally used in eyeglass production. These lenses can magnify objects only 6x-10x. Around 1595, the 1st compound microscope was invented by Zacharias Janssen (1580- 1638). It is believed that Zacharias probably had help from his father, Hans, because he was still young at that time. They made these microscopes by placing several lenses together, and discovered that objects were further enlarged upon viewing. In 1665, Robert Hooke (1635-1703) examined a thin slice of cork under the microscope that he built. He was able to see and observe small compartments of the cork. He initially named the small compartments cellula because they reminded him of the “little rooms” in the monastery. These eventually became known as cells. A few years later, Anton van Leeuwenhoek (1632-1723) created a microscope with a much higher magnification than the microscope the Hooke used. Leeuwenhoek used his microscope to observe specimens such as bacteria, blood, cells, and protists. The Cell Theory A century passed and several improvements on the microscope were made. These latest microscopes were used by Matthias Jakob Schleiden (1804-1881) and Theodor Schwann (1810-1882). Schleiden was a professor of botany at the University of Jena, Germany.  Schwann was a professor of physiology at the University of Louvain,Belgium. Schleiden and Schwann The first to point out that all plants and animals are composed of cells. CELL THEORY Schleiden published his research in 1838, which was based on several years of studying different types of plants under the microscope. Schwann published his research a year later in 1839, based on his study of several slides of animal cells. Their research became the basis of the first 2 postulates of cell theory. Basis of the 2 Postulates of the Cell Theory: 1. All organisms are made up of cells. 2. The basic unit of life is cells. 3. All cells come from preexisting cells. The last postulate was eventually proven by Rudolf Ludwig Karl Virchow in 1858. Virchow, studying how cells played a role in body diseases at that time, noticed that the existence of diseases in the organ and tissues come from affected cells.From this, he stated Omnis cellula e cellula, which means that all cells arise from preexisting cells. It was believed, however, that this discovery was initially made by Robert Remak, a Jewish scientist, in 1855, when he tried to prove the idea of cell division by hardening the cell membrane. Virchow and Remak Rudolph Carl Virchow (1821-1902, Germany) suggested that disease is a cellular problem. He stated that all cells come from pre-existing cells, a theory stated earlier by Robert Remak (1815-1865, Poland).