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- 1.
- Chapter 4 Cell Structure (Sections 4.1 - 4.7)
2.
- 4.1 Food for Thought
- Helpful intestinal bacteria make vitamins that mammals cant, and they crowd out more dangerous germs
3. Escherichia coliis one of the most common intestinal bacteria of warm-blooded animals only a few of the hundreds of types ( strains ) are harmful 4.
- E. coliO157:H7
- E. coliO157:H7 makes a potent toxin that can severely damage the lining of the human intestine
5. Causes serious illness in people who eat contaminated foods 6.
- 4.2 What, Exactly, Is a Cell?
- cell
-
- The smallest unit that has the properties of life
- Cells pictured are individual organisms (protists)
7.
- Traits Common to All Cells
- Although cells differ in size, shape, and function, each starts out with aplasma membrane ,cytoplasm , and a region of DNA (in eukaryotic cells, anucleus )
- plasma membrane
-
- A cells outermost membrane
- 8. Alipid bilayeris the structural foundation of cell membranes, includingorganellemembranes
9.
- Key Terms
- organelle
-
- Structure that carries out a specialized metabolic function inside a cell
- cytoplasm
-
- Semifluid substance enclosed by a cells plasma membrane
- nucleus
-
- Organelle with two membranes that holds a eukaryotic cells DNA
10.
- Single Cells
11.
- Bacterial Cell
- Bacteria are single-celled organisms
12. Archaeans are similar to bacteria in overall structure 13.
- Fig. 4.3a, p. 52
- plasma membrane
- ABacterial cell
- cytoplasm
- DNA
14.
- Plant Cell
15.
- Fig. 4.3b, p. 52
- BPlant cell
- plasma membrane
- DNA in nucleus
- cytoplasm
16.
- Animal Cell
17.
- Fig. 4.3c, p. 52
- CAnimal cell
- DNA in nucleus
- cytoplasm
- plasma membrane
18.
- Animation: Overview of Cells
19.
- Constraints on Cell Size
- S urface-to-volume ratiolimits cell size
20. If the cell gets too big, inward flow of nutrients and outward flow of wastes across the membrane will not be fast enough
- surface-to-volume ratio
-
- A relationship in which the volume of an object increases with the cube of the diameter, but surface area increases with the square of the diameter
21.
- Surface-to-Volume Ratio
- The physical relationship between increases in volume and surface area constrains cell size and shape
22.
- Animation: Surface-to-Volume Ratio
23.
- Cell Theory
- The cell is the structural and functional unit of all organisms
- cell theory
-
- Theory that all organisms consist of one or more cells, which are the basic unit of life
24.
- History of Cell Discovery
- 1665: Antoni van Leeuwenhoekfirst observedmany very small animalcules
25. Robert Hooke magnified a piece of thinly sliced cork andnamed the tiny compartments he observed cellae 26. 1820s: Robert Brown was first to identify a cell nucleus 27. Matthias Schleiden, hypothesized that a plant cell is an independentliving unit even when it is part of a plant 28. Schleiden and Theodor Schwann concluded that the tissues of animals as well as plants are composed of cells 29.
- Cell Theory
- Four generalizations constitute thecell theory :
-
- 1. Every living organism consists of one or more cells
- 30. 2. A cell is the smallest unit of life, individually alive even as part of a multicelled organism
31. 3. All living cells come from division of preexisting cells 32. 4. Cells contain hereditary material, which they pass to their offspring during division 33.
- Key Concepts
- What Is a Cell?
-
- A cell is the smallest unit of life
- 34. Each has a plasma membrane that separates its interior from the exterior environment
35. A cells interior contains cytoplasm and DNA 36.
- 4.3 Spying on Cells
- Most cells are far too small to see with the naked eye
37. We use different types of microscopes and techniques to reveal cells and their internal and external details 38.
- Types of Microscopes
- Light microscopes
39. Phase-contrast microscopes 40. Fluorescence microscope
- Electron microscopes
41. Transmission electron Microscopes 42. Scanning electron microscopes 43.
- Examples of Microscopes
- Compound light microscope
- Transmission electron microscope (TEM)
44.
- Fig. 4.5a, p. 54
- specimen
- prism that directs rays to ocular lens
- focusing knob
- illuminator
- condenser lens
- stage
- path of light rays (bottom to top) to eye
- ocular lens
- objective lenses
- light source (in base)
45.
- Fig. 4.5b, p. 54
- phosphor screen
- incoming electron beam
- condenser lens
- specimen on grid
- objective lens
- projective lens
46.
- Animation: How a Light Microscope Works
47.
- Different Views, Same Organism
- Fig. 4.6, p. 55
- ALight micrograph.
- BLight micrograph.
- CFluorescence micrograph.
- DA transmission electron micrograph reveals fantastically detailed images of internal structures.
- EA scanning electron micro-graph shows surface details. SEMs may be artificially colored to highlight specific details.
- A reflected light microscope captures light reflected from specimens.
- A phase-contrast microscope yields high-contrast images of trans- parent specimens. Dark areas have taken up dye.
- This image shows fluorescent light emitted by chlorophyll molecules in the cells.
48.
- Relative Sizes
49.
- Measurements
- Units of length:
-
- 1 centimeter (cm) = 1/100 meter, or 0.4 inch
- 50. 1 millimeter (mm) = 1/1000 meter, or 0.04 inch
51. 1 micrometer ( m) = 1/1,000,000 meter, or 0.00004 inch 52. 1 nanometer (nm) = 1/1,000,000,000 meter, or 0.00000004 inch 53. 1 meter = 10 2cm = 10 3mm = 10 6 m = 10 9nm 54.
- Key Concepts
- Microscopes
-
- Most cells are too small to see with the naked eye
- 55. We use different types of microscopes to reveal different details of their structure
56.
- Animation: How an Electron Microscope Works
57.
- 4.4 Membrane Structureand Function
- A cell membrane functions as a selectively permeable barrier that separates an internal environment from an external one
58. Membranes of most cells can be described as afluid mosaic of lipids (mainly phospholipids) and proteins 59. Lipids are organized as alipid bilayer : a double layer of lipids in which the nonpolar tails of both layers are sandwiched between the polar heads 60.
- Key Terms
- lipid bilayer
-
- Structural foundation of cell membranes; double layer of lipids arranged tail-to-tail
- fluid mosaic
-
- Model of a cell membrane as a two-dimensional fluid of mixed composition
61.
- A Lipid Bilayer
62.
- Basic Cell
- At its most basic, a cell is a lipid bilayer bubble filled with fluid
63.
- Membrane Proteins
- Proteins associated with a membrane carry out most membrane functions
64. All membranes havetransport proteins 65. Plasma membranes also havereceptor proteins ,adhesion proteins ,enzymes, andrecognition proteins 66.
- Key Terms
- transport protein
-
- Protein that passively or actively assists specific ions or molecules across a membrane
- adhesion protein
-
- Membrane protein that helps cells stick together in tissues
- receptor protein
-
- Binds to a particular substance outside of the cell
- recognition protein
-
- Tags a cell as belonging to self (ones own body)
67.
- Membrane Proteins
68.
- Recognition and Receptor Proteins
69.
- Transport Proteins
70.
- Fig. 4.8b-e, p. 57
- Lipid Bilayer
- Cytoplasm
- Extracellular Fluid
- EThis transport protein, an ATP synthase, makes ATP when hydrogen ions flow through its interior.
- BRecognition proteins such as this MHC molecule tag a cell as belonging to ones own body.
- CReceptor proteins such as this B cell receptor bind substances outside the cell. B cell receptors help the body eliminate toxins and infectious agents such as bacteria.
- DTransport proteins bind to molecules on one side of the membrane, and release them on the other side. This one transports glucose.
71.
- Animation: Cell Membranes
72.
- Variations on the Model
- Archaeans do not build phospholipids with fatty acids instead, the tails of archaean phospholipids form covalent bonds with one another
73. Archaean membranes are far more rigid than those of bacteria or eukaryotes 74.
- Key Concepts
- Cell Membranes
-
- All cell membranes consist mainly of a lipid bilayer and different types of proteins
- 75. The proteins carry out various tasks, including control over which substances cross the membrane
76.
- Animation: Lipid Bilayer Organization
77.
- Animation: Fluid Mosaic Model
78.
- 4.5 Bacteria and Archaeans
- Single-celled bacteria and archaeans are the smallest and most diverse forms of life:
-
- The cytoplasm containsribosomesandplasmids
- 79. A single, circular chromosome is located in anucleoid
80. Many have acell wall ,flagella orpili 81.
- Key Terms
- ribosome
-
- Organelle of protein synthesis
- plasmid
-
- Small circle of DNA in some bacteria and archaeans
- nucleoid
-
- Region of cytoplasm where the DNA is concentrated inside a bacterium or archaean
82.
- Key Terms
- flagellum
-
- Long, slender cellular structure used for motility
- pilus
-
- A protein filament that projects from the surface of some bacterial cells sex pilus
- cell wall
-
- Semi-rigid but permeable structure that surrounds the plasma membrane of some cells
83.
- Bacteria
84.
- Archaeans
85.
- Body Plan of Bacteriaand Archaeans
86.
- Fig. 4.11, p. 58
- flagellum
- cytoplasm,with ribosomes
- DNA in nucleoid
- pilus
- plasma membrane
- cell wall
- capsule
87.
- Animation: Typical Prokaryotic Cell
88.
- Cell Walls
- The cell wall of most archaeans consists of proteins
89. The wall of most bacteria consists of a polymer of peptides and polysaccharides 90. Sticky polysaccharides form a slime layer, or capsule, around the wall of many types of bacteria 91.
- Biofilms
- Biofilmsare shared living arrangements among bacteria and other microbial organisms
- biofilm
-
- Community of different types of microorganisms living within a shared mass of slime
- 92. May include bacteria, algae, fungi, protists, and archaeans
93.
- A Biofilm
- A biofilm organizes itself into neighborhoods, each with a distinct microenvironment that stems from its location within the biofilm and species that inhabit it
94.
- Key Concepts
- Bacteria and Archaea
-
- Archaeans and bacteria have few internal membrane-enclosed compartments
- 95. In general, they are the smallest and structurally the simplest cells, but they are also the most numerous
96.
- 4.6 Introducing Eukaryotic Cells
- All protists, fungi, plants, and animals are eukaryotes
- Eukaryotic cells start out life with membrane-enclosed organelles, including a nucleus
97. Most eukaryotic cells contain an endomembrane system (ER, vesicles, and Golgi bodies), mitochondria, and a cytoskeleton 98.
- Components of Eukaryotic Cells
99.
- Animal and Plant Cells
100.
- Fig. 4.13, p. 60
- nucleus
- cell wall
- central vacuole
- vacuole
- plasma membrane
- chloroplast
- mitochondrion
101.
- 4.7 The Nucleus
- The nucleus contains the cells genetic material (DNA)
102. In the nucleus, ribosome subunits are assembled in dense regions callednucleoli
- The nucleus has a double-membranednuclear envelopesurroundingnucleoplasm
103.
- Key Terms
- nucleolus
-
- In a cell nucleus, a dense, irregularly shaped region where ribosomal subunits are assembled
- nuclear envelope
-
- A double membrane that constitutes the outer boundary of the nucleus
- nucleoplasm
-
- Viscous fluid enclosed by the nuclear envelope
104.
- The Nuclear Envelope
- The nuclear membrane controls passage of certain molecules between the nucleus and the cytoplasm
105. Receptors and transporters stud both sides of the nuclear envelope; other proteins form nuclear pores 106. The outer bilayer of the double membrane is continuous with the membrane of the ER 107.
- The Nucleus
- Fig. 4.14, p. 61
- nucleoplasm
- nuclear envelope
- nuclear pore
- nucleolus
- ER
- cytoplasm
- DNA
108.
- Nuclear Pores
- Fig. 4.15, p. 61
- nuclear pore
- cytoplasm
- nuclear envelope (two lipid bilayers)
109.
- Animation: Nuclear Envelope
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