1.1 _ The Cell Theory and Cellular Structures and Functions_ General Biology 1 (Lecture and Laboratory).pdf

9/5/24, 7:03 PM 1.1 | The Cell Theory and Cellular Structures and Functions: General Biology 1 (Lecture and Laboratory) 1.1 | The Cell Theory and Cellular Structures and Functions At the end of the lesson, the students should be able to: explain th...

9/5/24, 7:03 PM 1.1 | The Cell Theory and Cellular Structures and Functions: General Biology 1 (Lecture and Laboratory) 1.1 | The Cell Theory and Cellular Structures and Functions At the end of the lesson, the students should be able to: explain the postulates of the Cell Theory. describe the structure and function of major cell organelles. Cell's Concepts in a Box To start with our lesson and to check your prior knowledge about this topic, you will accomplish this simple activity (https://dlsl.instructure.com/courses/32587/files/9305217?wrap=1) (https://dlsl.instructure.com/courses/32587/files/9305217/download?download_frd=1) about the cell organelles during your synchronous class. About the Cell Theory...... THE CELL THEORY describes the basic properties of all cells. The three scientists who contributed to the development of cell theory are Matthias Schleiden, Theodore Schwann, and Rudolf Virchow. https://dlsl.instructure.com/courses/32587/pages/1-dot-1-%7C-the-cell-theory-and-cellular-structures-and-functions?module_item_id=1387412 1/7 9/5/24, 7:03 PM 1.1 | The Cell Theory and Cellular Structures and Functions: General Biology 1 (Lecture and Laboratory) By the late 1830s, botanist Matthias Schleiden and zoologist Theodore Schwann were studying tissues and proposed the unified cell theory. The unified cell theory states that: all living things are composed of one or more cells; the cell is the basic unit of life, and new cells arise from existing cells. Rudolf Virchow later made important contributions to this theory. Schleiden and Schwann proposed spontaneous generation as the method for cell origination, but spontaneous generation (also called abiogenesis) was later disproven. Rudolf Virchow famously stated “Omnis cellula e cellula”… "All cells only arise from pre-existing cells“. The parts of the theory that did not have to do with the origin of cells, however, held up to scientific scrutiny and are widely agreed upon by the scientific community today. The generally accepted portions of the modern Cell Theory are as follows: 1. The cell is the fundamental unit of structure and function in living things. 2. All organisms are made up of one or more cells. 3. Cells arise from other cells through cellular division. The expanded version of the cell theory can also include: Cells carry genetic material passed to daughter cells during cellular division All cells are essentially the same in chemical composition Energy flow (metabolism and biochemistry) occurs within cells. What is a Cell? According to the Cell Theory, cells are the basic unit of life, meaning it is the smallest living entity that exhibits the characteristics of life (reproduction, metabolism, homeostasis, etc.). Inside every living cells are small structures or compartments called organelles. These organelles may be grouped together according to the role they play inside the cell. Some organelles function for protection, genetic control, energy processing, breakdown and storage, manufacture and distribution, and structural support and communication. Here are the organelles that may be found inside the cell: https://dlsl.instructure.com/courses/32587/pages/1-dot-1-%7C-the-cell-theory-and-cellular-structures-and-functions?module_item_id=1387412 2/7 9/5/24, 7:03 PM 1.1 | The Cell Theory and Cellular Structures and Functions: General Biology 1 (Lecture and Laboratory) Cell Membrane Structure: Phospholipid bilayer embedded with proteins (not an organelle per se, but a vital structure) Function: Semi-permeable and selective barrier surrounding the cell Cell Wall Structure: External outer covering made of cellulose (not an organelle per se, but a vital structure) Function: Provides support and mechanical strength; prevents excess water uptake Nucleus Structure: Double membrane structure with pores; contains an inner region called a nucleolus Function: Stores genetic material (DNA) as chromatin; the nucleolus is the site of ribosome assembly Ribosomes Structure: Two subunits made of RNA and protein; larger in eukaryotes (80S) than in prokaryotes (70S) Function: Site of polypeptide synthesis (this process is called translation) Mitochondrion Structure: Double membrane structure, inner membrane highly folded into internal cristae Function: Site of aerobic respiration (ATP production) https://dlsl.instructure.com/courses/32587/pages/1-dot-1-%7C-the-cell-theory-and-cellular-structures-and-functions?module_item_id=1387412 3/7 9/5/24, 7:03 PM 1.1 | The Cell Theory and Cellular Structures and Functions: General Biology 1 (Lecture and Laboratory) Chloroplast Structure: Double membrane structure with internal stacks of membranous discs (thylakoids) Function: Site of photosynthesis – manufactured organic molecules are stored in various plastids Endoplasmic Reticulum Structure: A membrane network that may be bare (smooth ER) or studded with ribosomes (rough ER) Function: Transports materials between organelles (smooth ER = lipids ; rough ER = proteins) Golgi Apparatus Structure: An assembly of vesicles and folded membranes located near the cell membrane Function: Involved in the sorting, storing, modification, and export of secretory products Vacuole (large and central) Structure: Fluid-filled internal cavity surrounded by a membrane (tonoplast) Function: Maintains hydrostatic pressure (animal cells may have small, temporary vacuoles) https://dlsl.instructure.com/courses/32587/pages/1-dot-1-%7C-the-cell-theory-and-cellular-structures-and-functions?module_item_id=1387412 4/7 9/5/24, 7:03 PM 1.1 | The Cell Theory and Cellular Structures and Functions: General Biology 1 (Lecture and Laboratory) Lysosome Structure: Membranous sacs filled with hydrolytic enzymes Function: Breakdown/hydrolysis of macromolecules Peroxisome Structure: Membranous sac containing a variety of catabolic enzymes Function: Catalyzes breakdown of toxic substances (e.g. H2O2) and other metabolites Cytoskeleton Structure: A filamentous scaffolding within the cytoplasm (fluid portion of the cytoplasm is the cytosol) Function: Provides internal structure and mediates intracellular transport (less developed in prokaryotes) Centrosome Structure: Microtubule organizing center (contains paired centrioles in animal cells but not plant cells) Function: Radiating microtubules form spindle fibers and contribute to cell division (mitosis/meiosis) For an interactive view of the different organelles present in cells, click here (https://www.cellsalive.com/cells/cell_model_js.htm). Want to play?? Click on this link (https://www.nationalgeographic.org/interactive/cell-explorers/%20) and explore what's https://dlsl.instructure.com/courses/32587/pages/1-dot-1-%7C-the-cell-theory-and-cellular-structures-and-functions?module_item_id=1387412 5/7