The Structure of the Cell: PowerPoint Lectures PDF

The Structure of the Cell PowerPoint Lectures for Campbell Biology: Concepts & Connections, Seventh Edition Reece, Taylor, Simon, and Dickey © 2012 Pearson Education, Inc. Lecture by Edward J. Zalisko Introduction to the Cell The Nucleus and Ri...

The Structure of the Cell PowerPoint Lectures for Campbell Biology: Concepts & Connections, Seventh Edition Reece, Taylor, Simon, and Dickey © 2012 Pearson Education, Inc. Lecture by Edward J. Zalisko Introduction to the Cell The Nucleus and Ribosomes The Endomembrane Energy-Converting The Cytoskeleton System Organelles and Cell Surfaces  INTRODUCTION TO THE CELL © 2012 Pearson Education, Inc. 4.1 Microscopes reveal the world of the cell  Using light microscopes, scientists studied – microorganisms, – animal and plant cells, and – some structures within cells.  In the 1800s, these studies led to cell theory, which states that – all living things are composed of cells and – cell is the basic structural and functional unit of life – all cells come from other cells. © 2012 Pearson Education, Inc. Figure 4.1B 10 m Human height 1m Length of some nerve and muscle Unaided eye cells 100 mm (10 cm) Chicken egg 10 mm (1 cm) Frog egg 1 mm Paramecium Light microscope Human egg 100 m Most plant and animal cells 10 m Nucleus Most bacteria Electron microscope Mitochondrion 1 m Smallest bacteria 100 nm Viruses Ribosome 10 nm Proteins Lipids 1 nm Small molecules 0.1 nm Atoms Figure 4.1A Figure 4.1C Figure 4.1D 4.2 The small size of cells relates to the need to exchange materials across the plasma membrane  The plasma membrane forms a flexible boundary between the living cell and its surroundings.  Phospholipids form a two-layer sheet called a phospholipid bilayer in which – hydrophilic heads face outward, exposed to water, and – hydrophobic tails point inward, shielded from water. © 2012 Pearson Education, Inc. 4.2 The small size of cells relates to the need to exchange materials across the plasma membrane  Membrane proteins are either – attached to the membrane surface or – embedded in the phospholipid bilayer.  Some proteins form channels or tunnels that shield ions and other hydrophilic molecules as they pass through the hydrophobic center of the membrane.  Other proteins serve as pumps, using energy to actively transport molecules into or out of the cell. © 2012 Pearson Education, Inc. Figure 4.2B Outside cell Hydrophilic Hydrophobic heads region of a protein Hydrophobic tails Hydrophilic region of Phospholipid Inside cell a protein Channel protein Proteins 4.3 Prokaryotic cells are structurally simpler than eukaryotic cells  Bacteria and archaea are prokaryotic cells.  All other forms of life are composed of eukaryotic cells. – Prokaryotic and eukaryotic cells have – a plasma membrane and – one or more chromosomes and ribosomes. – Eukaryotic cells have a – membrane-bound nucleus and – number of other organelles. – Prokaryotes have a nucleoid and no true organelles. © 2012 Pearson Education, Inc. 4.3 Prokaryotic cells are structurally simpler than eukaryotic cells  The DNA of prokaryotic cells is coiled into a region called the nucleoid, but no membrane surrounds the DNA.  The surface of prokaryotic cells may – be surrounded by a chemically complex cell wall, – have a capsule surrounding the cell wall, – have short projections that help attach to other cells or the substrate, or – have longer projections called flagella that may propel the cell through its liquid environment. © 2012 Pearson Education, Inc. Figure 4.3 Fimbriae Ribosomes Nucleoid Plasma membrane Cell wall Bacterial chromosome Capsule Flagella A TEM of the bacterium A typical rod-shaped Bacillus coagulans bacterium 4.4 Eukaryotic cells are partitioned into functional compartments  The structures and organelles of eukaryotic cells perform four basic functions. 1. The nucleus and ribosomes are involved in the genetic control of the cell. 2. The endoplasmic reticulum, Golgi apparatus, lysosomes, vacuoles, and peroxisomes are involved in the manufacture, distribution, and breakdown of molecules. © 2012 Pearson Education, Inc. 4.4 Eukaryotic cells are partitioned into functional compartments 3. Mitochondria in all cells and chloroplasts in plant cells are involved in energy processing. 4. Structural support, movement, and communication between cells are functions of the cytoskeleton, plasma membrane, and cell wall. © 2012 Pearson Education, Inc. 4.4 Eukaryotic cells are partitioned into functional compartments  The internal membranes of eukaryotic cells partition it into compartments.  Cellular metabolism, the many chemical activities of cells, occurs within organelles. © 2012 Pearson Education, Inc. 4.4 Eukaryotic cells are partitioned into functional compartments  Almost all of the organelles and other structures of animals cells are present in plant cells.  A few exceptions exist. – Lysosomes and centrioles are not found in plant cells. – Plant but not animal cells have – a rigid cell wall, – chloroplasts, and – a central vacuole. © 2012 Pearson Education, Inc. Figure 4.4A Smooth Rough NUCLEUS: endoplasmic endoplasmic Nuclear reticulum reticulum envelope Chromatin Nucleolus NOT IN MOST PLANT CELLS: Centriole Lysosome Peroxisome Ribosomes Golgi apparatus CYTOSKELETON: Microtubule Mitochondrion Intermediate filament Microfilament Plasma membrane Figure 4.4B Rough NUCLEUS: endoplasmic Nuclear envelope Chromatin reticulum Ribosomes Nucleolus Smooth Golgi endoplasmic apparatus reticulum NOT IN ANIMAL CYTOSKELETON: CELLS: Microtubule Central vacuole Intermediate Chloroplast filament Cell wall Microfilament Plasmodesma Mitochondrion Peroxisome Plasma membrane Cell wall of adjacent cell  THE NUCLEUS AND RIBOSOMES © 2012 Pearson Education, Inc. 4.5 The nucleus is the cell’s genetic control center  The nucleus – contains most of the cell’s DNA and – controls the cell’s activities by directing protein synthesis by making messenger RNA (mRNA).  DNA is associated with many proteins in structures called chromosomes. © 2012 Pearson Education, Inc. 4.5 The nucleus is the cell’s genetic control center  The nuclear envelope – is a double membrane and – has pores that allow material to flow in and out of the nucleus.  The nuclear envelope is attached to a network of cellular membranes called the endoplasmic reticulum. © 2012 Pearson Education, Inc. 4.5 The nucleus is the cell’s genetic control center  The nucleolus is – a prominent structure in the nucleus and – the site of ribosomal RNA (rRNA) synthesis which is one of the structural component of ribosomes. © 2012 Pearson Education, Inc. Figure 4.5 Nucleus Two membranes of nuclear envelope Chromatin Nucleolus Pore Endoplasmic reticulum Ribosomes 4.6 Ribosomes make proteins for use in the cell and export  Ribosomes are involved in the cell’s protein synthesis. – Ribosomes are synthesized from rRNA produced in the nucleolus. – Cells that must synthesize large amounts of protein have a large number of ribosomes. © 2012 Pearson Education, Inc. 4.6 Ribosomes make proteins for use in the cell and export  Some ribosomes are free ribosomes; others are bound. – Free ribosomes are – suspended in the cytoplasm and – typically involved in making proteins that function within the cytoplasm. – Bound ribosomes are – attached to the endoplasmic reticulum (ER) associated with the nuclear envelope and – associated with proteins packed in certain organelles or exported from the cell. © 2012 Pearson Education, Inc. Figure 4.6 Ribosomes ER Cytoplasm Endoplasmic reticulum (ER) Free ribosomes Bound ribosomes Colorized TEM showing ER and ribosomes mRNA Protein Diagram of a ribosome  THE ENDOMEMBRANE SYSTEM © 2012 Pearson Education, Inc. 4.7 Overview: Many cell organelles are connected through the endomembrane system  Many of the membranes within a eukaryotic cell are part of the endomembrane system.  Some of these membranes are physically connected and some are related by the transfer of membrane segments by tiny vesicles (sacs made of membrane).  Many of these organelles work together in the – synthesis, – storage, and – export of molecules. © 2012 Pearson Education, Inc. 4.7 Overview: Many cell organelles are connected through the endomembrane system  The endomembrane system includes – the nuclear envelope, – endoplasmic reticulum (ER), – Golgi apparatus, – lysosomes, – vacuoles, and – the plasma membrane. © 2012 Pearson Education, Inc. 4.8 The endoplasmic reticulum is a biosynthetic factory  There are two kinds of endoplasmic reticulum— smooth and rough. – Smooth ER lacks attached ribosomes. – Rough ER lines the outer surface of membranes. – Although physically interconnected, smooth and rough ER differ in structure and function. © 2012 Pearson Education, Inc. Figure 4.8A Nuclear envelope Ribosomes Smooth ER Rough ER Figure 4.8B Transport vesicle buds off 4 Secretory mRNA protein inside trans- Ribosome port vesicle 3 1 Sugar chain Glycoprotein 2 Polypeptide Rough ER 4.8 The endoplasmic reticulum is a biosynthetic factory  Smooth ER is involved in a variety of diverse metabolic processes. – Smooth ER produces enzymes important in the synthesis of lipids, oils, phospholipids, and steroids. – Other enzymes help process drugs, alcohol, and other potentially harmful substances. – Some smooth ER helps store calcium ions. © 2012 Pearson Education, Inc. 4.8 The endoplasmic reticulum is a biosynthetic factory  Rough ER makes – additional membrane for itself and – proteins destined for secretions. © 2012 Pearson Education, Inc. 4.9 The Golgi apparatus finishes, sorts, and ships cell products  The Golgi apparatus serves as a molecular warehouse and finishing factory for products manufactured by the ER. – Products travel in transport vesicles from the ER to the Golgi apparatus. – One side of the Golgi apparatus functions as a receiving dock for the product and the other as a shipping dock. – Products are modified as they go from one side of the Golgi apparatus to the other and travel in vesicles to other sites. © 2012 Pearson Education, Inc. Figure 4.9 “Receiving” side of Golgi apparatus Golgi Golgi apparatus apparatus 1 Transport Transport vesicle vesicle from from ER 2 the Golgi 3 4 4 “Shipping” side of Golgi apparatus 4.10 Lysosomes are digestive compartments within a cell  A lysosome is a membranous sac containing digestive enzymes. – The enzymes and membrane are produced by the ER and transferred to the Golgi apparatus for processing. – The membrane serves to safely isolate these potent enzymes from the rest of the cell. © 2012 Pearson Education, Inc. 4.10 Lysosomes are digestive compartments within a cell  Lysosomes help digest food particles engulfed by a cell. 1. A food vacuole binds with a lysosome. 2. The enzymes in the lysosome digest the food. 3. The nutrients are then released into the cell. © 2012 Pearson Education, Inc. Figure 4.10A_s1 Digestive enzymes Lysosome Plasma membrane Figure 4.10A_s2 Digestive enzymes Lysosome Food vacuole Plasma membrane Figure 4.10A_s3 Digestive enzymes Lysosome Food vacuole Plasma membrane Figure 4.10A_s4 Digestive enzymes Lysosome Digestion Food vacuole Plasma membrane 4.10 Lysosomes are digestive compartments within a cell  Lysosomes also help remove or recycle damaged parts of a cell. 1. The damaged organelle is first enclosed in a membrane vesicle. 2. Then a lysosome – fuses with the vesicle, – dismantles its contents, and – breaks down the damaged organelle. © 2012 Pearson Education, Inc. Figure 4.10B_s1 Lysosome Vesicle containing damaged mitochondrion Figure 4.10B_s2 Lysosome Vesicle containing damaged mitochondrion Figure 4.10B_s3 Lysosome Vesicle containing Digestion damaged mitochondrion 4.11 Vacuoles function in the general maintenance of the cell  Vacuoles are large vesicles that have a variety of functions. – Some protists have contractile vacuoles that help to eliminate water from the protist. – In plants, vacuoles may – have digestive functions, – contain pigments, or – contain poisons that protect the plant. © 2012 Pearson Education, Inc. Figure 4.11A Contractile vacuoles Nucleus Figure 4.11B Central vacuole Chloroplast Nucleus 4.12 A review of the structures involved in manufacturing and breakdown  The following figure summarizes the relationships among the major organelles of the endomembrane system. © 2012 Pearson Education, Inc. Figure 4.12 Nucleus Nuclear membrane Rough ER Transport vesicle from Smooth Golgi to ER Transport plasma vesicle from ER membrane to Golgi Golgi Lysosome Vacuole Plasma apparatus membrane  ENERGY-CONVERTING ORGANELLES © 2012 Pearson Education, Inc. 4.13 Mitochondria harvest chemical energy from food  Mitochondria are organelles that carry out cellular respiration in nearly all eukaryotic cells.  Cellular respiration converts the chemical energy in foods to chemical energy in ATP (adenosine triphosphate). © 2012 Pearson Education, Inc. 4.13 Mitochondria harvest chemical energy from food  Mitochondria have two internal compartments. 1. The intermembrane space is the narrow region between the inner and outer membranes. 2. The mitochondrial matrix contains – the mitochondrial DNA, – ribosomes, and – many enzymes that catalyze some of the reactions of cellular respiration. © 2012 Pearson Education, Inc. Figure 4.13 Mitochondrion Outer membrane Intermembrane space Inner membrane Cristae Matrix 4.14 Chloroplasts convert solar energy to chemical energy  Chloroplasts are the photosynthesizing organelles of all photosynthesizing eukaryotes.  Photosynthesis is the conversion of light energy from the sun to the chemical energy of sugar molecules. © 2012 Pearson Education, Inc. 4.14 Chloroplasts convert solar energy to chemical energy  Chloroplasts are partitioned into compartments. – Between the outer and inner membrane is a thin intermembrane space. – Inside the inner membrane is – a thick fluid called stroma that contains the chloroplast DNA, ribosomes, and many enzymes and – a network of interconnected sacs called thylakoids. – In some regions, thylakoids are stacked like poker chips. Each stack is called a granum,where green chlorophyll molecules trap solar energy. © 2012 Pearson Education, Inc. Figure 4.14 Inner and Chloroplast Granum Stroma outer membranes Thylakoid 4.15 EVOLUTION CONNECTION: Mitochondria and chloroplasts evolved by endosymbiosis  Mitochondria and chloroplasts have – DNA and – ribosomes.  The structure of this DNA and these ribosomes is very similar to that found in prokaryotic cells. © 2012 Pearson Education, Inc. 4.15 EVOLUTION CONNECTION: Mitochondria and chloroplasts evolved by endosymbiosis  The endosymbiont theory proposes that – mitochondria and chloroplasts were formerly small prokaryotes and – they began living within larger cells. © 2012 Pearson Education, Inc. Figure 4.15 Mitochondrion Nucleus Endoplasmic reticulum Engulfing of photosynthetic Some prokaryote cells Engulfing Chloroplast of oxygen- Host cell using prokaryote Mitochondrion Host cell  THE CYTOSKELETON AND CELL SURFACES © 2012 Pearson Education, Inc. 4.16 The cell’s internal skeleton helps organize its structure and activities  Cells contain a network of protein fibers, called the cytoskeleton, which functions in structural support and motility.  Scientists believe that motility and cellular regulation result when the cytoskeleton interacts with proteins called motor proteins. © 2012 Pearson Education, Inc. 4.16 The cell’s internal skeleton helps organize its structure and activities  The cytoskeleton is composed of three kinds of fibers. 1. Microfilaments (actin filaments) support the cell’s shape and are involved in motility. 2. Intermediate filaments reinforce cell shape and anchor organelles. 3. Microtubules (made of tubulin) give the cell rigidity and act as tracks for organelle movement. © 2012 Pearson Education, Inc. Figure 4.16 Nucleus Nucleus Actin subunit Fibrous subunits Tubulin subunits 7 nm 10 nm 25 nm Microfilament Intermediate filament Microtubule 4.17 Cilia and flagella move when microtubules bend  While some protists have flagella and cilia that are important in locomotion, some cells of multicellular organisms have them for different reasons. – Cells that sweep mucus out of our lungs have cilia. – Animal sperm are flagellated. © 2012 Pearson Education, Inc. Figure 4.17A Cilia Figure 4.17B Flagellum CONNECTION: Problems with sperm motility may be environmental or genetic  In developed countries over the last 50 years, there has been a decline in sperm quality.  The causes of this decline may be – environmental chemicals or – genetic disorders that interfere with the movement of sperm and cilia. Primary ciliary dyskinesia (PCD) is a rare disease characterized by recurrent infections of the respiratory tract and immotile sperm. © 2012 Pearson Education, Inc. 4.19 The extracellular matrix of animal cells functions in support and regulation  Animal cells synthesize and secrete an elaborate extracellular matrix (ECM) that – helps hold cells together in tissues and – protects and supports the plasma membrane. © 2012 Pearson Education, Inc. Figure 4.19 Glycoprotein EXTRACELLULAR FLUID complex with long polysaccharide Collagen fiber Connecting glycoprotein Integrin Plasma membrane CYTOPLASM Microfilaments of cytoskelton 4.20 Three types of cell junctions are found in animal tissues  Adjacent cells communicate, interact, and adhere through specialized junctions between them. – Tight junctions prevent leakage of extracellular fluid across a layer of epithelial cells. – Anchoring junctions fasten cells together into sheets. – Gap junctions are channels that allow molecules to flow between cells. © 2012 Pearson Education, Inc. Figure 4.20 Tight junctions prevent fluid from moving between cells Tight junction Anchoring junction Gap junction Plasma membranes of adjacent cells Extracellular matrix 4.21 Cell walls enclose and support plant cells  A plant cell, but not an animal cell, has a rigid cell wall that – protects and provides skeletal support that helps keep the plant upright against gravity and – is primarily composed of cellulose.  Plant cells have cell junctions called plasmodesmata that serve in communication between cells. © 2012 Pearson Education, Inc. Figure 4.21 Plant cell walls Vacuole Plasmodesmata Primary cell wall Secondary cell wall Plasma membrane Cytoplasm