Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Cell Structure Chapter 3 Table of Contents Section 1 Looking at.

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Cell Structure Chapter 3 Table of Contents Section 1 Looking at Cells Section 2 Cell Features Section 3 Cell Organelles

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Looking at Cells Objectives Describe how scientists measure the length of objects. Relate magnification and resolution in the use of microscopes. Analyze how light microscopes function. Compare light microscopes with electron microscopes. Describe the scanning tunneling microscope. Chapter 3

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Cells Under the Microscope Measuring Measuring Cell Structures Measurements taken by scientists are expressed in metric units. The official name of the metric system is the International System of Measurements, abbreviated SI. Section 1 Looking at Cells Chapter 3

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Cells Under the Microscope, continued What is Magnification?Magnification making an image appear larger than its actual size. What is Resolution? a measure of the clarity of an image. Both high magnification and good resolution are needed to view the details of extremely small objects clearly. Section 1 Looking at Cells Chapter 3

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Cells Under the Microscope, continued Electron microscopes have much higher magnifying and resolving powers than light microscopes. Section 1 Looking at Cells Chapter 3

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Types of Microscopes Light microscopes Light microscopes form an image when light passes through one or more lenses to produce an enlarged image of a specimen. Section 1 Looking at Cells Chapter 3

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Cell Features Objectives List the three parts of the cell theory. Determine why cells must be relatively small. Compare the structure of prokaryotic cells with that of eukaryotic cells. Describe the structure of cell membranes. Chapter 3

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu The Cell TheoryCell Theory The Cell Theory has three parts: 1.All living things are made of one or more cells. 2.Cells are the basic units of structure and function in organisms. 3.All cells arise from existing cells. Section 2 Cell Features Chapter 3

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu The Cell Theory, continued Cell Size Small cells function more efficiently than large cells. If a cell’s surface area–to-volume ratio is too low, substances cannot enter and leave the cell well enough to meet the cell’s needs. Section 2 Cell Features Chapter 3

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Prokaryotes Prokaryotes are single-celled organisms that lack a nucleus and other internal compartments. They have a cell wall, may have cilia or flagella, and have a single circular molecule of DNA. Section 2 Cell Features Chapter 3

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu The Cell Membrane The cell membrane is a selectively permeable barrier that determines which substances enter and leave the cell. The selective permeability of the cell is mainly caused by the way phospholipids interact with water. A phospholipid is a lipid made of a phosphate group and two fatty acids. Section 2 Cell Features Chapter 3

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu The Cell Membrane, continued Cell membranes are made of a double layer of phospholipids, called a bilayer. Section 2 Cell Features Chapter 3

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Objectives Describe the role of the nucleus in cell activities. Analyze the role of internal membranes in protein production. Summarize the importance of mitochondria in eukaryotic cells. Identify three structure in plant cells that are absent from animal cells. Section 3 Cell Organelles Chapter 3

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu The Nucleus The nucleus is an internal compartment that houses the cell’s DNA. Most functions of a eukaryotic cell are controlled by the cell’s nucleus. The nucleus is surrounded by a double membrane called the nuclear envelope. Scattered over the surface of the nuclear envelope are many small channels called nuclear pores. Section 3 Cell Organelles Chapter 3

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu The Nucleus, continued Ribosomal proteins and RNA are made in the nucleus. Ribosomes are partially assembled in a region of the nucleus called the nucleolus. Section 3 Cell Organelles Chapter 3

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Ribosomes and the Endoplasmic Reticulum Ribosomes are the cellular structures on which proteins are made. The Endoplasmic Reticulum or ER is an extensive system of internal membranes that move proteins and other substances through the cell. Section 3 Cell Organelles Chapter 3

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Ribosomes and the Endoplasmic Reticulum, continued The part of the ER with attached ribosomes is called the rough ER. The rough ER helps transport proteins that are made by the attached ribosomes. New proteins enter the ER. The portion of the ER that contains the completed protein pinches off to form a vesicle. A vesicle is a small, membrane-bound sac that transports substances in cells. Section 3 Cell Organelles Chapter 3

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Ribosomes and the Endoplasmic Reticulum, continued The ER moves proteins and other substances within eukaryotic cells. Section 3 Cell Organelles Chapter 3

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Ribosomes and the Endoplasmic Reticulum, continued Packaging and Distribution of Proteins Vesicles that contain newly made proteins move through the cytoplasm from the ER to an organelle called the Golgi apparatus. The Golgi apparatus is a set of flattened, membrane- bound sacs that serve as the packaging and distribution center of the cell. Section 3 Cell Organelles Chapter 3

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Mitochondria Mitochondria are organelles that harvest energy from organic compounds to make ATP. ATP is the main energy currency of cells. Most ATP is made inside the mitochondria. Section 3 Cell Organelles Chapter 3

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Mitochondria, continued Mitochondria have two membranes. The outer membrane is smooth. The inner membrane is greatly folded, and has a large surface area. Mitochondria have their own DNA. Mitochondria reproduce independently of the cell. Mitochondrial DNA is similar to the DNA of prokaryotic cells. Mitochondria are thought to be descendents of primitive prokaryotes. Section 3 Cell Organelles Chapter 3

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Structures of Plant Cells Plants have three unique structures that are not found in animal cells: Cell Wall Chloroplasts Central Vacuole Section 3 Cell Organelles Chapter 3

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Structures of Plant Cells, continued The cell membrane of plant cells is surrounded by a thick cell wall, composed of proteins and carbohydrates. The cell wall helps support and maintain the shape of the cell protects the cell from damage connects the cell with adjacent cells Section 3 Cell Organelles Chapter 3

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Structures of Plant Cells, continued Chloroplasts are organelles that use light energy to make carbohydrates from carbon dioxide and water. Chloroplasts, along with mitochondria, supply much of the energy needed to power the activities of plant cells. Chloroplasts, like mitochondria, have their own DNA and reproduce independently of the plant cell. Chloroplasts, like mitochondria, are thought to be descendents of ancient prokaryotes. Section 3 Cell Organelles Chapter 3

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Structures of Plant Cells, continued Central Vacuole: Most of a plant cell’s volume is taken up by a large, membrane-bound space called the central vacuole. The central vacuole stores water and may contain ions, nutrients, and wastes. Section 3 Cell Organelles Chapter 3

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Cell Structure Chapter 3 Table of Contents Section 1 Looking at.

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Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Cell Structure Chapter 3 Table of Contents Section 1 Looking at.

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