© 2010 Pearson Education, Inc. Lectures by Chris C. Romero, updated by Edward J. Zalisko PowerPoint ® Lectures for Campbell Essential Biology, Fourth Edition – Eric Simon, Jane Reece, and Jean Dickey Campbell Essential Biology with Physiology, Third Edition – Eric Simon, Jane Reece, and Jean Dickey Chapter 3 A Tour of the Cell

© 2010 Pearson Education, Inc. THE MICROSCOPIC WORLD OF CELLS Organisms are either –Single-celled, such as most prokaryotes and protists or –Multicelled, such as plants, animals, and most fungi

© 2010 Pearson Education, Inc. Microscopes as Windows on the World of Cells Light microscopes can be used to explore the structures and functions of cells. When scientists examine a specimen on a microscope slide –Light passes through the specimen –Lenses enlarge, or magnify, the image

© 2010 Pearson Education, Inc. Magnification is an increase in the specimen’s apparent size. Resolving power is the ability of an optical instrument to show two objects as separate.

© 2010 Pearson Education, Inc. The electron microscope (EM) uses a beam of electrons, which results in better resolving power than the light microscope. Two kinds of electron microscopes reveal different parts of cells.

© 2010 Pearson Education, Inc. The electron microscope can –Magnify up to 100,000 times –Distinguish between objects 0.2 nanometers apart

Light Microoscope(LM) (for viewing living cells) Light microscope of a protist, Paramecium LM Colorized SEM Scanning Electron Microscope (SEM) (for viewing surface features) Scanning electron microscope of Paramecium TYPES OF MICROSCOPES Transmission Electron Microscope(TEM) (for viewing internal structures) Transmission electron microscope of Paramecium Colorized TEM Figure 4.1

Figure 4.2

© 2010 Pearson Education, Inc. Fig. 3-5, pp

© 2010 Pearson Education, Inc. Cells were first described in 1665 by Robert Hooke.

© 2010 Pearson Education, Inc. Rudolf Virchow studied cell reproduction and came up with the cell theory (1858). Cell theory

© 2010 Pearson Education, Inc. The Two Major Categories of Cells 1. Prokaryotic 2. Eukaryotic cells

© 2010 Pearson Education, Inc. Prokaryotic CellsEukaryotic Cells Smaller Simpler Most do not have organelles Found in bacteria and archaea Larger More complex Have organelles Found in protists, plants, fungi, animals CATEGORIES OF CELLS Figure 4.UN12

© 2010 Pearson Education, Inc. Fig. 3-3, p. 45

© 2010 Pearson Education, Inc. Cells 3 things common to all cells Characteristics of the cell membrane

© 2010 Pearson Education, Inc. (a) Phospholipid bilayer of membrane (b) Fluid mosaic model of membrane Outside of cell Hydrophilic head Hydrophobic tail Hydrophilic region of protein Hydrophilic head Hydrophobic tail Hydrophobic regions of protein Phospholipid bilayer Phospholipid Proteins Cytoplasm (inside of cell) Figure 4.6 Cell membrane

© 2010 Pearson Education, Inc. Molecules inside a cell are in constant motion  Concentration- # of molecules of a substance in a specified volume of water  Gradient- 1 region of fluid contains more molecules than another region

© 2010 Pearson Education, Inc. Diffusion how most substances are moved across the cell membrane examples: H 2 0, 0 2, CO 2

© 2010 Pearson Education, Inc. Figure 6.9 Diffusion Leads to Uniform Distribution of Solutes

© 2010 Pearson Education, Inc. Osmosis

© 2010 Pearson Education, Inc. Solutes  Concentration of dissolved substances  If solute concentrations are equal on both sides of the cell membrane – no net movement of water in either direction  If solute concentrations are not equal- water moves form a hypotonic solution to a hypertonic solution

© 2010 Pearson Education, Inc. Solutes Hypotonic Hypertonic Isotonic

© 2010 Pearson Education, Inc. Salt sucks water moves from hypotonic to hypertonic

© 2010 Pearson Education, Inc. Osmosis Can Modify the Shapes of Cells

© 2010 Pearson Education, Inc. Animation 5-1  Diffusion and osmosis

© 2010 Pearson Education, Inc.  Small molecules readily diffuse across the cell membrane.  Glucose and other larger molecules rarely diffuse freely across the cell membrane.

© 2010 Pearson Education, Inc. Mechanisms by which large molecules cross the cell membrane 1. Facilitated diffusion 2. Active transport 3. Exocytosis 4. Endocytosis

© 2010 Pearson Education, Inc. 1. Facilitated diffusion

© 2010 Pearson Education, Inc. 2. Active transport

© 2010 Pearson Education, Inc. Animation 5-2  Passive and active transport

© 2010 Pearson Education, Inc. 3. Endocytosis 4. Exocytosis

© 2010 Pearson Education, Inc. Phagocytosis

© 2010 Pearson Education, Inc. Animation 5-3  endo/ exocytosis

© 2010 Pearson Education, Inc. Prokaryotic cells- bacteria

© 2010 Pearson Education, Inc. An Overview of Eukaryotic Cells Eukaryotic cells are fundamentally similar. The region between the nucleus and plasma membrane is the cytoplasm. Cytoplasm- fluid portion of the cell Organelles are suspended in the cytoplasm

© 2010 Pearson Education, Inc. Organelle Membrane bound sac that has a specific function Physically separate chemical reactions inside the cell Separate different chemical reactions in time

Cytoskeleton Ribosomes Centriole Lysosome Flagellum Nucleus Plasma membrane Mitochondrion Rough endoplasmic reticulum (ER) Golgi apparatus Smooth endoplasmic reticulum (ER) Idealized animal cell Not in most plant cells Figure 4.5a

Idealized plant cell Cytoskeleton Mitochondrion Nucleus Rough endoplasmic reticulum (ER) Ribosomes Smooth endoplasmic reticulum (ER) Golgi apparatus Plasma membrane Channels between cells Central vacuole Cell wall Chloroplast Not in animal cells Figure 4.5b

© 2010 Pearson Education, Inc. Types of organelles in eukaryotic cells 1. nucleus

THE NUCLEUS AND RIBOSOMES: GENETIC CONTROL OF THE CELL The nucleus is the chief executive of the cell. –Genes in the nucleus store information necessary to produce proteins. –Proteins do most of the work of the cell. © 2010 Pearson Education, Inc.

Structure and Function of the Nucleus The nucleus is bordered by a double membrane called the nuclear membrane. Pores in the envelope allow materials to move between the nucleus and cytoplasm. The nucleus contains a nucleolus where ribosomes are made.

Ribosomes ChromatinNucleolus Pore Nuclear envelope Figure 4.8a

Surface of nuclear envelope TEM Figure 4.8b

Nuclear pores TEM Figure 4.8c

© 2010 Pearson Education, Inc. Stored in the nucleus are long DNA molecules and associated proteins that form fibers called chromatin. Each long chromatin fiber constitutes one chromosome. The number of chromosomes in a cell depends on the species.

DNA molecule Chromosome Proteins Chromatin fiber Figure 4.9

© 2010 Pearson Education, Inc. Types of organelles 2. Ribosomes

© 2010 Pearson Education, Inc. Ribosome components are made in the nucleolus but assembled in the cytoplasm. Ribosomes may assemble proteins: –Suspended in the fluid of the cytoplasm or –Attached to the outside of an organelle called the endoplasmic reticulum

Ribosome Protein mRNA Figure 4.10

Ribosomes in cytoplasm Ribosomes attached to endoplasmic reticulum TEM Figure 4.11

© 2010 Pearson Education, Inc. Types of organelles 3. Endoplasmic reticulum (ER)

Nuclear envelope Smooth ER Rough ER Ribosomes Figure 4.13a

Ribosomes TEM Rough ER Smooth ER Figure 4.13b

© 2010 Pearson Education, Inc. Rough ER The “rough” in the rough ER is due to ribosomes that stud the outside of the ER membrane. These ribosomes produce membrane proteins and secretory proteins. After the rough ER synthesizes a molecule, it packages the molecule into transport vesicles.

Proteins are often modified in the ER. Secretory proteins depart in transport vesicles. Vesicles bud off from the ER. A ribosome links amino acids into a polypeptide. Ribosome Transport vesicle Polypeptide Protein Rough ER Figure 4.14

© 2010 Pearson Education, Inc. Smooth ER The smooth ER –Lacks surface ribosomes –Produces lipids, including steroids

© 2010 Pearson Education, Inc. Types of organelles 4. Golgi body

Transport vesicle from rough ER “Receiving” side of Golgi apparatus New vesicle forming Transport vesicle from the Golgi Plasma membrane “Shipping” side of Golgi apparatus Figure 4.15a

“Receiving” side of Golgi apparatus New vesicle forming Colorized SEM Figure 4.15b

© 2010 Pearson Education, Inc. Types of organelles 5. Vesicles are membranous sacs that bud from the ER, golgi body and plasma membrane

© 2010 Pearson Education, Inc. vesicle lysosome – cells main organelle of digestion Sac of digestive enzymes Found in animal cells Enzymes in a lysosome can break down large molecules such as –Proteins –Polysaccharides –Fats –Nucleic acids

© 2010 Pearson Education, Inc. Lysosomes can also –Destroy harmful bacteria –Break down damaged organelles

Plasma membraneDigestive enzymes Lysosome Digestion Food vacuole (a) Lysosome digesting food Figure 4.16a

Lysosome Digestion (b) Lysosome breaking down the molecules of damaged organelles Vesicle containing damaged organelle Figure 4.16b

Vesicle containing two damaged organelles Organelle fragment TEM Figure 4.16c

© 2010 Pearson Education, Inc. Figure 5.10 The Endomembrane System

© 2010 Pearson Education, Inc. Animation 4-2  endomembrane system

© 2010 Pearson Education, Inc. Types of organelles 6. Mitochondria Uses oxygen to extract energy from glucose Produce ATP- the energy source for nearly all cell acivities

Outer membrane Inner membrane Cristae Matrix Space between membranes TEM Figure 4.20

© 2010 Pearson Education, Inc. Components specific to plant cells 1. Chloroplasts Photosynthesis is the conversion of light energy from the sun to the chemical energy of sugar. Most of the living world runs on the energy provided by photosynthesis.

Inner and outer membranes Space between membranes Stroma (fluid in chloroplast) Granum TEM Figure 4.19

© 2010 Pearson Education, Inc. Light energy Chloroplast Mitochondrion Chemical energy (food) ATP PHOTOSYNTHESIS CELLULAR RESPIRATION Figure 4.UN14 CHLOROPLASTS AND MITOCHONDRIA: ENERGY CONVERSION

© 2010 Pearson Education, Inc. Components specific to plant cells 2. Cell wall Cellulose deposits outside the cell membrane Cells of plants stick together wall to wall

© 2010 Pearson Education, Inc. Idealized plant cell Cytoskeleton Mitochondrion Nucleus Rough endoplasmic reticulum (ER) Ribosomes Smooth endoplasmic reticulum (ER) Golgi apparatus Plasma membrane Channels between cells Central vacuole Cell wall Chloroplast Not in animal cells Figure 4.5b

© 2010 Pearson Education, Inc. Components specific to plant cells 3. Central vacuole Store nutrients Absorb water

(b) Central vacuole in a plant cell Central vacuole Colorized TEM Figure 4.17b

THE CYTOSKELETON: CELL SHAPE AND MOVEMENT The cytoskeleton is a network of fibers extending throughout the cytoplasm. © 2010 Pearson Education, Inc.

Maintaining Cell Shape Cytoskeleton- cell movement and internal organization - Microfilaments and microtubules

© 2010 Pearson Education, Inc. The cytoskeleton contains several types of fibers made from different proteins: –Microtubules –straight and hollow –guide the movement of organelles and chromosomes –Microfilaments are thinner and solid

(a) Microtubules in the cytoskeleton (b) Microtubules and movement LM Figure 4.21

© 2010 Pearson Education, Inc. Types of microtubules  spindle microtubules  flagella  cilia  centrioles

© 2010 Pearson Education, Inc. Cilia and Flagella Cilia and flagella aid in movement. –Flagella propel the cell in a whiplike motion. –Cilia move in a coordinated back-and- forth motion.

© 2010 Pearson Education, Inc. Cilia may extend from nonmoving cells. On cells lining the human trachea, cilia help sweep mucus out of the lungs.

(a) Flagellum of a human sperm cell Colorized SEM (b) Cilia on a protist (c) Cilia lining the respiratory tract Colorized SEM Figure 4.22