Transcript Chapter 4
Enlarges image formed by objective lens Eyepiece Magnifies specimen, forming primary image Objective lens Focuses light through specimen Ocular lens Specimen Condenser lens Light source Transmission electron microscopy (TEM) micrograph of a peroxisome from the marine snail Gibulla umbilicalis. Head Louse INTRODUCTION TO THE CELL Copyright © 2009 Pearson Education, Inc. Pili Nucleoid Ribosomes Plasma membrane Bacterial chromosome Cell wall Capsule A typical rod-shaped bacterium Flagella A thin section through the bacterium Bacillus coagulans (TEM) Animal Cell Organelles Smooth endoplasmic reticulum NUCLEUS: Chromosomes Nucleolus Rough endoplasmic reticulum Lysosome Ribosomes CYTOSKELETON: Microtubule Intermediate filament Microfilament Golgi apparatus Plasma membrane Mitochondrion NUCLEUS: Rough endoplasmic reticulum Chromosome Ribosomes Nucleolus Smooth endoplasmic reticulum Golgi apparatus CYTOSKELETON: Central vacuole Microtubule Chloroplast Intermediate filament Cell wall Microfilament Mitochondrion Peroxisome Plasma membrane Cell wall of adjacent cell Plant Cell Organelles 4.4 Eukaryotic cells are partitioned into functional compartments There are four life processes in eukaryotic cells that depend upon structures and organelles – Manufacturing – Breakdown of molecules – Energy processing – Structural support, movement, and communication Copyright © 2009 Pearson Education, Inc. 4.4 Eukaryotic cells are partitioned into functional compartments Manufacturing involves the nucleus, ribosomes, endoplasmic reticulum, and Golgi apparatus – Manufacture of a protein, perhaps an enzyme, involves all of these Copyright © 2009 Pearson Education, Inc. Cellular Organelles - Nucleus The nucleus contains most of the DNA in a eukaryotic cell In the nucleus, DNA and proteins form genetic material called chromatin Chromatin condenses to form discrete chromosomes (during cell division) Two membranes of nuclear envelope Nucleus Nucleolus Chromatin Pore Endoplasmic reticulum Ribosomes Ribosomes: Protein Factories • Ribosomes are particles made of ribosomal RNA and protein • Ribosomes carry out protein synthesis • Cells that must synthesize large amounts of protein have a large number of ribosomes Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 6-11 Cytosol Endoplasmic reticulum (ER) Free ribosomes Bound ribosomes Large subunit 0.5 µm TEM showing ER and ribosomes Small subunit Diagram of a ribosome The endomembrane system: all these membranes are related through direct contact or through vesicles • Components of the endomembrane system: – Nuclear envelope – Endoplasmic reticulum – Golgi apparatus – Lysosomes – Vacuoles – Plasma membrane • A vesicle is a tiny spherical package of molecules surrounded by a membrane Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Endoplasmic Reticulum: Biosynthetic Factory • There are two distinct regions of ER: – Smooth ER, which lacks ribosomes – Rough ER, with ribosomes studding its surface – One synthesizes lipids and the other functions in protein synthesis. Which do you think is which? Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings 4.9 The endoplasmic reticulum is a biosynthetic factory • Smooth ER is involved in a variety of diverse metabolic processes – involved in the synthesis of lipids, oils, phospholipids, and steroids Copyright © 2009 Pearson Education, Inc. 4.9 The endoplasmic reticulum is a biosynthetic factory • Rough ER makes additional membrane for itself and proteins destined for secretion – Once proteins are synthesized, they are transported in vesicles to other parts of the endomembrane system Copyright © 2009 Pearson Education, Inc. 4.10 The Golgi apparatus finishes, sorts, and ships cell products • The Golgi apparatus functions in conjunction with the ER by modifying products of 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 Copyright © 2009 Pearson Education, Inc. “Receiving” side of Golgi apparatus Golgi apparatus Transport vesicle from ER New vesicle forming “Shipping” side of Golgi apparatus Transport vesicle from the Golgi Golgi apparatus Lysosomes: Digestive Compartments • A lysosome is a membranous sac of hydrolytic enzymes that can digest macromolecules • Lysosomal enzymes can hydrolyze proteins, fats, polysaccharides, and nucleic acids Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings • Some types of cell can engulf another cell/bacteria by phagocytosis; this forms a vacuole • A lysosome fuses with the vacuole and digests the molecules • Lysosomes also use enzymes to recycle the cell’s own organelles and macromolecules, a process called autophagy Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 6-14 Nucleus 1 µm Vesicle containing two damaged organelles 1 µm Mitochondrion fragment Peroxisome fragment Lysosome Digestive enzymes Lysosome Plasma membrane Lysosome Peroxisome Digestion Food vacuole Vesicle (a) Phagocytosis (b) Autophagy Mitochondrion Digestion Video • Examples • Lets follow the path of insulin – This is a protein that will be secreted from the pancreatic cell • Antibodies – These are defensive proteins that will be secreted from the white blood cell Video Transport vesicle buds off 4 Ribosome Secretory protein inside transport vesicle 3 Sugar chain 1 2 Glycoprotein Polypeptide Rough ER 4.4 Eukaryotic cells are partitioned into functional compartments Breakdown of molecules involves lysosomes, vacuoles, and peroxisomes – Breakdown of an internalized bacterium by a phagocytic cell would involve all of these Copyright © 2009 Pearson Education, Inc. Digestive enzymes Lysosome Plasma membrane Food vacuole Digestion 4.12 Vacuoles function in the general maintenance of the cell Vacuoles are membranous sacs that are found in a variety of cells and possess an assortment of functions – Examples are the central vacuole in plants with hydrolytic functions, pigment vacuoles in plants to provide color to flowers, and contractile vacuoles in some protists to expel water from the cell Copyright © 2009 Pearson Education, Inc. Chloroplast Nucleus Central vacuole 4.4 Eukaryotic cells are partitioned into functional compartments Energy processing involves mitochondria in animal cells and chloroplasts in plant cells – Generation of energy-containing molecules, such as adenosine triphosphate, occurs in mitochondria and chloroplasts Copyright © 2009 Pearson Education, Inc. Mitochondrion Outer membrane Intermembrane space Inner membrane Cristae Matrix Chloroplast Stroma Inner and outer membranes Granum Intermembrane space 4.4 Eukaryotic cells are partitioned into functional compartments Structural support, movement, and communication involve the cytoskeleton, plasma membrane, and cell wall – An example of the importance of these is the response and movement of phagocytic cells to an infected area Copyright © 2009 Pearson Education, Inc. Nucleus Nucleus Actin subunit Fibrous subunits 7 nm Microfilament Tubulin subunit 10 nm 25 nm Intermediate filament Microtubule Cross sections: Outer microtubule doublet Central microtubules Radial spoke Flagellum Dynein arms Plasma membrane Triplet Basal body Basal body 4.4 Eukaryotic cells are partitioned into functional compartments There are four life processes in eukaryotic cells that depend upon structures and organelles – Manufacturing – Breakdown of molecules – Energy processing – Structural support, movement, and communication Copyright © 2009 Pearson Education, Inc. Nucleus Golgi apparatus Smooth ER Rough ER Ribosome Lysosomes Vacuoles Perixisomes Chloroplast Mitochondria a. l. b. c. k. j. i. h. d. g. e. f. Quiz 3 Matching: can be used more than once 1. Which organelle is involved in manufacture of protein? 2. Which organelles acts as a kind of recycling center for the cell and breaks down old molecules so they can be used again? 3. Which organelle acts as an energy transformer? 4. A cell that’s primary function is to produce protein would have a lot of_____________. Copyright © 2009 Pearson Education, Inc. a. Mitchondria b. Vacuole c. Ribosome d. Lysosome Quiz 3 5. Name one difference between plant and animal cells. 6. What is the most important macromolecule found the nucleus of a cell? 7. T/F One function of the cytoskeleton is to give support to the cell. 8. T/F Vesicles are similar to little circular bubbles that can carry proteins around in the cell. 9. T/F The Golgi apparatus stores, modifies, and packages proteins. 10. Would you like to get a point for answering this question? Copyright © 2009 Pearson Education, Inc. Hydrophilic heads Outside cell Hydrophobic region of protein Hydrophobic tails Inside cell Proteins Hydrophilic region of protein 4.5 The structure of membranes correlates with their functions The plasma membrane controls the movement of molecules into and out of the cell, a trait called selective permeability – The structure of the membrane with its component molecules is responsible for this characteristic – Membranes are made of lipids, proteins, and some carbohydrate, but the most abundant lipids are phospholipids Copyright © 2009 Pearson Education, Inc. Hydrophilic head Phosphate group Symbol Hydrophobic tails 4.20 The extracellular matrix of animal cells functions in support, movement, and regulation Cells synthesize and secrete the extracellular matrix (ECM) that is essential to cell function – The ECM is composed of strong fibers of collagen, which holds cells together and protects the plasma membrane Copyright © 2009 Pearson Education, Inc. Glycoprotein complex with long polysaccharide EXTRACELLULAR FLUID Collagen fiber Connecting glycoprotein Integrin Plasma membrane Microfilaments CYTOPLASM 4.21 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 Animation: Desmosomes Animation: Gap Junctions Animation: Tight Junctions Copyright © 2009 Pearson Education, Inc. 4.21 Cell junctions are found in plant tissues Plasmodesmata Cytoplasmic streaming Copyright © 2009 Pearson Education, Inc. Tight junctions Anchoring junction Gap junctions Plasma membranes of adjacent cells Extracellular matrix