Module 2: Understanding Cells - PDF

SAN MATEO MUNICIPAL COLLEGE NATSCI01: BIOLOGICAL SCIENCE General Luna St., Guitnang Bayan I, San Mateo, Rizal Mrs. Vilma C. Alfonso Tel. No. (02) 997-9070 www.smmc.edu.p...

SAN MATEO MUNICIPAL COLLEGE NATSCI01: BIOLOGICAL SCIENCE General Luna St., Guitnang Bayan I, San Mateo, Rizal Mrs. Vilma C. Alfonso Tel. No. (02) 997-9070 www.smmc.edu.ph MODULE 2: UNDERSTANDING THE CELLS: The Building Pieces of Life LEARNING OBJECTIVES: At the end of the module, you must be able to: 1. explain the cell theory; 2. recognize the significant contributions of biologist in cell discovery; 3. classify cell types according to number of cells, structure, and function; 4. distinguish the difference between the features of prokaryotic and eukaryotic cells; 5. explain the parts and functions of plant cell and animal cell, and 6. discuss the different transport mechanisms in cell. INPUT INFORMATION: Cells are the basic structural and functional unit of all living organisms. With theinvention of microscope, scientists are able todiscoverand study cells. Cytology is the study of cell which includes its structure, function and processes. Cells are composed of different parts which has a specific function. Every cell is different but there is a basic structure that is common to all cells. A cell is essentially genetic material in a gel-like substance surrounded by a membrane. STRUCTURE OF A CELL DNA is the genetic material of cells is found as molecules. It holds all the information that a cell needs to keep itself alive. It contains a code that can be translated by a cell and tells it how to perform different tasks. Gene is a specific segment of a DNA molecule and each gene tells a cell how to perform different tasks. It is a specific segment of a DNA molecule and each gene tells a cell how to perform one specific task. Cytoplasm is a gel-like substance that the genetic material is found. It fills a cell and gives its shape. It allows for different materials to move around the cell. All cells have other structures in their cytoplasm that help the cell stay alive. The cytoplasm of all cells is surrounded by a membrane called the plasma membrane. The plasma membrane separates the cell from the outside world and keeps the contents of the cell together. The plasma membrane provides a barrier that substances have to pass through before they can enter or exit a cell.  The concept of CellTheory is summarized into three statements – all living things are structurally made up of cells; the cell is the fundamental unit of life; and cells come from the division of pre-existing cells. There are several scientists who made significant contribution in the study of cell. Through the ideas of Matthias Schleiden, Theodor Schwann, and Rudolf Virchow, the Cell Theory was formulated. Cell types can be classified according to number of cells, function and structure. a. Based on number of cells:  Unicellular are single-celled organisms that can reproduce through asexual reproduction such as budding and fission. They ingest and digest their own food which is used for their reproduction, growth and development.  Multicellular are consisting of many different cells which carries on basic and specific life activities like accumulating, synthesizing, metabolizing complex molecules for survival. b. Based on function:  Somatic cells, also called body cells, are diploid cells which maintains life processes of the organisms such as metabolism, growth and repair.  Gametes, also called reproductive or sex cells, are haploid cells that functions for the production of offspring. These are the egg cell and sperm cell of an organism. c. Based on structure:  Prokaryote (before the nucleus) lacks membrane-bound organelles which is found in bacteria.  Eukaryote (true nucleus) has distinct nucleus and organelles enclosed in membrane which is exhibited by plants and animals. An organelle literally means “little organs”, refers to any of the various cellular structures that perform a distinctive function inside a cell.. In strict definition, an organelle is a membrane-bound compartment or structure in a cell that performs a special function.  Comparison Chart Eukaryotic Cell versus Prokaryotic Eukaryotic Cell Prokaryotic Cell Nucleus Present Absent Number of chromosomes More than one One--but not true chromosome: Plasmids Cell Type Usually multicellular Usually unicellular (some cyanobacteria may be multicellular) True Membrane bound Nucleus Present Absent Lysosomes and peroxisomes Present Absent Microtubules Present Absent Endoplasmic reticulum Present Absent Mitochondria Present Absent Cytoskeleton Present Absent Ribosomes larger smaller Vesicles Present Present Golgi apparatus Present Absent Chloroplasts Present(in plants) Absent; chlorophyll scattered in the cytoplasm Cell wall Only in plant cells and fungi Usually chemically complex (chemically simpler) Vacuoles Present Present Cell size 10-100um 1-10um Cell Type Usually multicellular Usually unicellular (some cyanobacteria may be multicellular) Example Animals and Plants Bacteria and archaea Differences between Plant Cell and Animal Cell  Both plant and animal cells are eukaryotic, so they contain membrane-bound organelles like the nucleus and mitochondria.  Both animal and plant cells have mitochondria, but only plant cells have chloroplasts. Plants don’t get their sugar from eating food, so they need to make sugar from sunlight. This process (photosynthesis) takes place in the chloroplast. Once the sugar is made, it is then broken down by the mitochondria to make energy for the cell. Because animals get sugar from the food they eat, they do not need chloroplasts: just mitochondria.  Both plant and animal cells have vacuoles. A plant cell contains a large, singular vacuole that is used for storage and maintaining the shape of the cell. In contrast, animal cells have many, smaller vacuoles.  Plant cells have a cell wall, as well as a cell membrane. In plants, the cell wall surrounds the cell membrane. This gives the plant cell its unique rectangular shape. Animal cells simply have a cell membrane, but no cell wall.  Plant Cell Anatomy The cell is the basic unit of life. Plant cells (unlike animal cells) are surrounded by a thick, rigid cell wall. Glossary of Plant Cell Anatomy Terms: ATP ATP is short for adenosine triphosphate; it is a high-energy molecule used for energy storage by organisms. In plant cells, ATP is produced in the cristae of mitochondria and chloroplasts. Cell membrane is the thin layer of protein and fat that surrounds the cell, but is inside the cell wall. The cell membrane is semipermeable, allowing some substances to pass into the cell and blocking others. Cell wall A thick, rigid membrane that surrounds a plant cell. This layer of cellulose fiber gives the cell most of its support and structure. The cell wall also bonds with other cell walls to form the structure of the plant. Centrosome (The “microtubule organizing centre”) A small body located near the nucleus - it has a dense center and radiating tubules. The centrosomes is where microtubules are made. During cell division (mitosis), the centrosome divides and the two parts move to opposite sides of the dividing cell. Unlike the centrosomes in animal cells, plant cell centrosomes do not have centrioles. Chlorophyll Chlorophyll is a molecule that can use light energy from sunlight to turn water and carbon dioxide gas into sugar and oxygen (this process is called photosynthesis). Chlorophyll is magnesium based and is usually green. Chloroplast An elongated or disc-shaped organelle containing chlorophyll. Photosynthesis (in which energy from sunlight is converted into chemical energy - food) takes place in the chloroplasts. Cytoplasm The jellylike material outside the cell nucleus in which the organelles are located. Golgi body (The Golgi apparatus or Golgi complex) A flattened, layered, sac-like organelle that looks like a stack of pancakes and is located near the nucleus. The Golgi body packages proteins and carbohydrates into membrane-bound vesicles for “export” from the cell. Granum (Plural grana) A stack of thylakoid disks within the chloroplast is called a granum. Mitochondrion Spherical to rod-shaped organelles with a double membrane. The inner membrane is infolded many times, forming a series of projections (called cristae). The mitochondrion converts the energy stored in glucose into ATP (adenosine triphosphate) for the cell. Nuclear membrane The membrane that surrounds the nucleus. Nucleolus An organelle within the nucleus - it is where ribosomal RNA is produced. Nucleus Spherical body containing many organelles, including the nucleolus. The nucleus controls many of the functions of the cell (by controlling protein synthesis) and contains DNA (in chromosomes). The nucleus is surrounded by the nuclear membrane. Photosynthesis A process in which plants convert sunlight, water, and carbon dioxide into food energy (sugars and starches), oxygen and water. Chlorophyll or closely-related pigments (substances that color the plant) are essential to the photosynthetic process. Ribosome Small organelles composed of RNA-rich cytoplasmic granules that are sites of protein synthesis. Rough endoplasmic reticulum (Rough ER) A vast system of interconnected, membranous, infolded and convoluted sacks that are located in the cell’s cytoplasm (the ER is continuous with the outer nuclear membrane). Rough ER is covered with ribosomes that give it a rough appearance. Rough ER transport materials through the cell and produces proteins in sacks called cisternae (which are sent to the Golgi body, or inserted into the cell membrane). Smooth endoplasmic reticulum (Smooth ER) A vast system of interconnected, membranous, infolded and convoluted tubes that are located in the cell’s cytoplasm (the ER is continuous with the outer nuclear membrane). The space within the ER is called the ER  lumen. Smooth ER transport materials through the cell. It contains enzymes and produces and digests lipids (fats) and membrane proteins; smooth ER buds off from rough ER, moving the newly-made proteins and lipids to the Golgi body and membranes Stroma Part of the chloroplasts in plant cells, located within the inner membrane of chloroplasts, between the grana. Thylakoid disk Thylakoid disks are disk-shaped membrane structures in chloroplasts that contain chlorophyll. Chloroplasts are made up of stacks of thylakoid disks; a stack of thylakoid disks is called a granum. Photosynthesis (the production of ATP molecules from sunlight) takes place on thylakoid disks. Vacuole A large, membrane-bound space within a plant cell that is filled with fluid. Most plant cells have a single vacuole that takes up much of the cell. It helps maintain the shape of the cell. Animal Cell Anatomy The cell is the basic unit of life. All organisms are made up of cells (or in some cases, a single cell). Most cells are very small; in fact, most are invisible without using a microscope. Cells are covered by a cell membrane and come in many different shapes. The contents of a cell are called the protoplasm. Glossary of Animal Cell Terms: Cell Membrane The thin layer of protein and fat that surrounds the cell. The cell membrane is semipermeable, allowing some substances to pass into the cell and blocking others. Centrosome (Microtubule Organizing Center) A small body located near the nucleus - it has a dense center and radiating tubules. The centrosomes is where microtubules are made. During cell division (mitosis), the centrosome divides and the two parts move to opposite sides of the dividing cell. The centriole is the dense center of the centrosome. Cytoplasm The jellylike material outside the cell nucleus in which the organelles are located. Golgi body (Golgi Apparatus/Golgi Complex) A flattened, layered, sac-like organelle that looks like a stack of pancakes and is located near the nucleus. It produces the membranes that surround the lysosomes. The Golgi body packages proteins and carbohydrates into membrane-bound vesicles for “export” from the cell. Lysosome (Cell Vesicles) Round organelles surrounded by a membrane and containing digestive enzymes. This is where the digestion of cell nutrients takes place. Mitochondrion Spherical to rod-shaped organelles with a double membrane. The inner membrane is infolded many times, forming a series of projections (called cristae). The mitochondrion converts the energy stored in glucose into ATP (adenosine triphosphate) for the cell. Nuclear Membrane The membrane that surrounds the nucleus. Nucleolus An organelle within the nucleus - it is where ribosomal RNA is produced. Some cells have more than one nucleolus. Nucleus Spherical body containing many organelles, including the nucleolus. The nucleus controls many of the functions of the cell (by controlling protein synthesis) and contains DNA (in chromosomes). The nucleus is surrounded by the nuclear membrane. Ribosome Small organelles composed of RNA-rich cytoplasmic granules that are sites of protein synthesis. Rough Endoplasmic Reticulum (Rough ER) A vast system of interconnected, membranous, infolded and convoluted sacks that are located in the cell’s cytoplasm (the ER is continuous with the outer nuclear membrane). Rough ER is covered with ribosomes that give it a rough appearance. Rough ER transports materials through the cell and produces proteins in sacks called cisternae (which are sent to the Golgi body, or inserted into the cell membrane). Smooth Endoplasmic Reticulum (Smooth ER) A vast system of interconnected, membranous, infolded and convoluted tubes that are located in the cell’s cytoplasm (the ER is continuous with the outer nuclear membrane). The space within the ER is called the ER lumen. Smooth ER transports materials through the cell. It contains enzymes and produces and digests lipids (fats) and membrane proteins; smooth ER buds off from rough ER, moving the newly-made proteins and lipids to the Golgi body, lysosomes, and membranes. Vacuole Fluid-filled, membrane-surrounded cavities inside a cell. The vacuole fills with food being digested and waste material that is on its way out of the cell. _____________________________________________________________________________ ASSIGNMENT: 1. What are the phases of the cell cycle? 2. Discuss the stages of mitosis and meiosis. 3. Illustrate the process of mitosis and meiosis. 4. Enumerate disorders and diseases that result from the malfunction of the cell during cell cycle. LEARNING RESOURCES: Books: Morano, Lourdes N (2011)., Fundamentals of Biology. Quezon City: Lorimar Publishing, Inc. Chanco, Christine R (2005)., Biological Science. Paranaque City: ACNN Printing Press Online Resources: https://www.khanacademy.org/science/high-school-biology/hs-cells/hs-plant-vs-animal-cells/ https://www.vedantu.com/biology/difference-between-plant-cell-and-animal-cell https://byjus.com/biology/difference-between-plant-cell-and-animal-cell/ https://youtu.be/-zafJKbMPA8 https://youtu.be/HBvfBB_oSTc http://www.enchantedlearning.com/subjects/animals/cell/ https://www.youtube.com/watch?v=gFuEo2ccTPA https://basicbiology.net/biology-101/introduction-to-cells#:~:text=Introduction%20to%20cells. https://www.diffen.com/difference/Eukaryotic_Cell_vs_Prokaryotic_Cell