Cell Structure & Functions PDF

Lesson 1.2 Components of the Cell: Major Parts of the Cell General Biology 1[1/2] Science, Technology, Engineering, and Mathematics In cities, buildings cater various forms of services to increase productivity. They also have structures and other security measures that regulate the entry and ex...

Lesson 1.2 Components of the Cell: Major Parts of the Cell General Biology 1[1/2] Science, Technology, Engineering, and Mathematics In cities, buildings cater various forms of services to increase productivity. They also have structures and other security measures that regulate the entry and exit of people. 2 Our cells also rely on biomolecules that provide shape and rigidity to them. In addition, our cells manage to become selective to the molecules that will move through it. 3 How can one distinguish the major parts of the cell? 4 Learning Competency At the end of the lesson, you should be able to do the following: Describe the structure and function of the major organelles (STEM_BIO11/12-Ia-c-2). 5  Learning Objectives At the end of the lesson, you should be able to do the following: Distinguish between the different structural components of the plasma membrane. Describe the diverse roles of proteins in membranes. Compare the structure and function of microfilaments, intermediate filaments, and microtubules. 6  Learning Objectives At the end of the lesson, you should be able to do the following: Describe the function and composition of cytoplasm. Describe the structure and function of the cell wall. 7 Overview of the Regions of the Cell The cell has three major divisions, namely, the plasma membrane, the cytoplasm, and the nucleus. 8 Overview of the Regions of the Cell The cell consists of both membrane-bound and non-membrane-bound organelles. 9 How do the major cellular structures help in the different cellular processes? 10  Structural Components of the Plasma Membrane Roles of Roles of Structure Lipid Bilayer Membrane Proteins Plasma Membrane Cytoskeleton Cytoplasm Cell Wall The plasma membrane is the cell’s primary barrier. 11  Structural Components of the Plasma Membrane Roles of Roles of Structure Lipid Bilayer Membrane Proteins Plasma Membrane Cell membrane or plasma membrane separates the cytoplasm from external Cytoskeleton environment. Cytoplasm It comprises the following: ❖ phospholipids ❖ glycolipids Cell Wall ❖ cholesterol ❖ glycoproteins ❖ membrane proteins 12  Structural Components of the Plasma Membrane Roles of Roles of Structure Lipid Bilayer Membrane Proteins Plasma Membrane Each of the phospholipids consists of the following: Cytoskeleton ○ head region phosphate group Cytoplasm hydrophilic ○ tail region Cell Wall two fatty acid chains hydrophobic 13  Structural Components of the Plasma Membrane Roles of Roles of Structure Lipid Bilayer Membrane Proteins Plasma Membrane Phospholipids make up the phospholipid bilayer. Cytoskeleton ○ two phospholipid layers Phosphate heads face the Cytoplasm cytoplasm and the cell’s exterior. Fatty acid tails are sandwiched. Cell Wall 14  Structural Components of the Plasma Membrane Roles of Roles of Structure Lipid Bilayer Membrane Proteins Plasma Membrane The fluid mosaic model describes the membrane structure. Cytoskeleton ○ mosaic of different molecules such as proteins, sugars, and cholesterol Cytoplasm ○ fluidity due to its natural viscosity Cell Wall 15  Structural Components of the Plasma Membrane Roles of Roles of Structure Lipid Bilayer Membrane Proteins Plasma Membrane Membrane fluidity is determined by: ○ the “kinks” in the fatty acid tails of Cytoskeleton the phospholipids ○ the cholesterol molecules which act Cytoplasm as regulators of fluidity Cell Wall 16  Structural Components of the Plasma Membrane Roles of Roles of Structure Lipid Bilayer Membrane Proteins Plasma Membrane Selective permeability is an important property of the lipid bilayer, in which it Cytoskeleton only allows certain molecules to move into and out of the cell. Cytoplasm Cell Wall 17  Structural Components of the Plasma Membrane Roles of Roles of Structure Lipid Bilayer Membrane Proteins Plasma Membrane Permeable Cytoskeleton Lipids Alcohol small molecules Cytoplasm carbon oxygen nitrogen dioxide water Cell Wall 18  Structural Components of the Plasma Membrane Roles of Roles of Structure Lipid Bilayer Membrane Proteins Plasma Membrane Impermeable Cytoskeleton polar molecules large molecules Cytoplasm amino nucleic glucose proteins Cell Wall acids acids 19  Structural Components of the Plasma Membrane Roles of Roles of Structure Lipid Bilayer Membrane Proteins Plasma Membrane Cytoskeleton Cytoplasm Cell Wall Transport proteins in the membrane may either be in the form of carrier proteins or channel proteins 20  Structural Components of the Plasma Membrane Roles of Roles of Structure Lipid Bilayer Membrane Proteins Plasma Membrane channel passageway of certain proteins molecules Membrane Proteins Cytoskeleton change conformation carrier proteins to transport molecules Cytoplasm cell recognition detect invading proteins pathogens Cell Wall receptor binding of molecules to proteins trigger responses 21  The Cytoskeletal Elements Intermediate Microtubules Microfilaments Filaments Plasma Membrane This consists of a network of Cytoskeleton protein fibers that gives the cell its Cytoplasm structural framework. Cell Wall The cytoskeletal elements can be observed by using fluorescence techniques. 22  The Cytoskeletal Elements Intermediate Microtubules Microfilaments Filaments Plasma Membrane Cytoskeleton Cytoplasm In addition to providing a structural framework to the cell, the Cell Wall cytoskeleton also serves other functions such as movement of organelles, macromolecules, and chromosomes. 23  The Cytoskeletal Elements Intermediate Microtubules Microfilaments Filaments Plasma Membrane These consist of helically arranged globular proteins called tubulin. Cytoskeleton Cytoplasm Cell Wall A microtubule is a helix of ɑ-tubulin and β-tubulin subunits. 24  The Cytoskeletal Elements Intermediate Microtubules Microfilaments Filaments Plasma Membrane It radiate from the centrosomes Form spindle fibers that move chromosomes Cytoskeleton Cytoplasm Cell Wall A microtubule is a helix of ɑ-tubulin and β-tubulin subunits. 25  The Cytoskeletal Elements Intermediate Microtubules Microfilaments Filaments Plasma Membrane They consist of long fibers of Cytoskeleton actin protein, making them the Cytoplasm thinnest cytoskeleton. Cell Wall Fluorescent actin microfilaments from mouse embryo 26  The Cytoskeletal Elements Intermediate Microtubules Microfilaments Filaments Plasma Membrane They help facilitate cell and Cytoskeleton organelle movement. Cytoplasm They can help change the Cell Wall shape of the cell. Fluorescent actin microfilaments from mouse embryo 27  The Cytoskeletal Elements Intermediate Microtubules Microfilaments Filaments Plasma Membrane Helps maintain cell shape Anchors the nucleus Cytoskeleton Cytoplasm Cell Wall Intermediate filaments provide structural integrity to the plasma membrane 28  Structural Components of the Cytoplasm Plasma Membrane This is where all different subcellular Cytoskeleton structures are suspended. Cytoplasm Cross-section view of a plant cell showing organelles in the Cell Wall cytoplasm 29  Structural Components of the Cytoplasm Plasma Membrane It is composed of the cytosol, a semifluid Cytoskeleton solution that consists of Cytoplasm water and inorganic and Cross-section view of a plant Cell Wall organic cell showing organelles in the cytoplasm molecules. 30  Structural Components of the Cell Wall Plasma Membrane Cell wall is a rigid structure that surrounds the cell membrane. Cytoskeleton It helps maintain the shape of cells and prevent them from bursting. Cytoplasm Cell Wall 31  Structural Components of the Cell Wall Plasma Membrane Most bacteria have cell wall made up of Cytoskeleton peptidoglycan. Cytoplasm The cell wall in some fungi Cell Wall consists of Bacterial cell capsule chitin. consists of peptidoglycan 32  Structural Components of the Cell Wall Plasma Membrane In plant cells, the cell wall consists of mesh-like cellulose fibers. Cytoskeleton Cytoplasm Cell Wall Plant cell walls prevent the cell from bursting should excess water is absorbed. 33 Is it possible to make an artificial cell from scratch? 34  Check Your Understanding Identify the major cellular structure being described in each of the following items. 1. It is a major organelle that is composed of hydrophilic heads and hydrophobic tails. 2. It is a group of membrane proteins that changes their shape to be able to transport substances into and out of the cell. 3. It is a rigid structure that provides protection and support to bacterial, plant, and fungal cells. 35  Check Your Understanding In each of the given situations below, determine which cellular structure is involved. Thereafter, briefly justify your answer. 1. Polar substances cannot pass through the middle part of the cell’s barrier. 2. This membrane protein changes its shape when certain molecules are bound to it. 3. This is the most stable cytoskeletal element also gives strength to the skin. 36  Let’s Sum It Up! The cell is divided into main regions: ○ The plasma membrane is mostly composed of phospholipids. It serves as the primary barrier of the cell and is semi-permeable in nature. ○ The cytoskeleton is composed of microtubules, microfilaments, and intermediate filaments. The cytoskeletal elements provide support and framework and facilitate motility in cells. 37  Let’s Sum It Up! The cell is divided into main regions: ○ The cytoplasm is a jelly-like structure composed of the semi-fluid cytosol where all organelles and other cellular contents are immersed or suspended. ○ The cell wall is made up of peptidoglycan in bacterial cells and cellulose in plant cells. It gives a rigid structure for the cell and prevents it from bursting. 38 Let’s Sum It Up! The plasma membrane, cytoplasm, cytoskeleton, and cell wall all contribute to the cell’s maintenance and survival. 39 Challenge Yourself A pathogen invaded an organism’s body. Justify how some cells of the body will recognize it to elicit the necessary immune response. 40  Photo Credit Bibliography Hoefnagels, Marielle. Biology: The Essentials. 2nd ed. McGraw-Hill Education, 2016. Mader, Sylvia S., and Michael Windelspecht. Biology. 11th ed. McGraw-Hill Education, 2014. Slide 26-27: MEF microfilaments by Y tambe Reece, Jane B, Martha R. Taylor, Eric J. Simon, Jean is licensed under CC BY-SA 3.0 via L. Dickey, and Kelly Hogan. Biology Wikipedia. Concepts and Connections. 8th ed. Pearson Education South Asia Pte Ltd, 2016. Simon, Eric J., and Jane B. Reece. Campbell Essential Biology. 5th ed. Pearson Education Inc. 2013. Starr, Cecie, Christine A. Evers, and Lisa Starr. Biology Today and Tomorrow. 4th ed. Cengage Learning Asia Pte Ltd, 2014. 41