a tour of the cell, part i chapter 4 microscopes as windows on cells o types of microscopes o...
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A Tour of the Cell, Part ICHAPTER 4A Tour of the Cell, Part ICHAPTER 4Microscopes as Windows on Cells
o Types of Microscopes
o Magnification and Resolution
Categories of Cells
Features of Prokaryotic Cells
Features of Eukaryotic Cells
o Membrane Structure
o Nucleus and Ribosomes
o Endoplasmic Reticulum (ER)
Cells Are Small (1-100 m)
Magnification and Resolution in Microscopy
• Magnification is the ability of a microscope to enlarge an image.
-Magnification is almost unlimited on a microscope.
• Resolution is the ability of a microscope to clearly define the details of what it is looking at.
-Microscopes that use lower wavelengths of electromagnetic energy, like electron microscopes, have better resolution of tiny details and can be used at higher magnifications (100,000X).
-Resolution limits the usefulness of high magnification since once an object becomes blurry; greater magnification doesn't help. Light microscopes are limited to 1000X.
The Microscopic World of Cells
• Cells were first discovered in 1665 by Robert Hooke.
• The accumulation of scientific evidence led to the cell theory which has two main tenets:
1. All living things are composed of cells.
2. All cells are formed from previously existing cells.
• Organisms are either:
– Single-celled, such as most bacteria and protists
– Multicellular, such as plants, animals, and most fungi
Types of Microscopes
• Light Microscopes use visible light and optical lenses
– Limited to 1000X because of low resolution
– Require little or no electrical power to operate
Euglena
• Electron microscopes (EMs) use a beam of electrons and magnetic lenses
– Much higher resolving power than the light microscope and can magnify up to 100,000X.
Types of Microscopes
– Types of Electron Microscopes
• The scanning electron microscope (SEM) is used to study the detailed architecture of the surface of a cell.
• The transmission electron microscope (TEM) is useful for exploring the internal structure of a cell.
A Tour of the Cell, Part ICHAPTER 4A Tour of the Cell, Part ICHAPTER 4Microscopes as Windows on Cells
o Types of Microscopes
o Magnification and Resolution
Categories of Cells
Features of Prokaryotic Cells
Features of Eukaryotic Cells
o Membrane Structure
o Nucleus and Ribosomes
o Endoplasmic Reticulum (ER)
The Two Major Categories of Cells
• The countless cells on earth fall into two categories:
– Prokaryotic cells, such as bacteria
– Eukaryotic cells, such as protist, fungal, plant, or animal cells
Comparison of Prokaryotic and Eukaryotic Cells
A Tour of the Cell, Part ICHAPTER 4A Tour of the Cell, Part ICHAPTER 4Microscopes as Windows on Cells
o Types of Microscopes
o Magnification and Resolution
Categories of Cells
Features of Prokaryotic Cells
Features of Eukaryotic Cells
o Membrane Structure
o Nucleus and Ribosomes
o Endoplasmic Reticulum (ER)
Prokaryotic Cells Are Small and Simple
A Tour of the Cell, Part ICHAPTER 4A Tour of the Cell, Part ICHAPTER 4Microscopes as Windows on Cells
o Types of Microscopes
o Magnification and Resolution
Categories of Cells
Features of Prokaryotic Cells
Features of Eukaryotic Cells
o Membrane Structure
o Nucleus and Ribosomes
o Endoplasmic Reticulum (ER)
Eukaryotic Cells are Larger and More Complex
Eukaryotic Cells are Larger and More Complex
A Tour of the Cell, Part ICHAPTER 4A Tour of the Cell, Part ICHAPTER 4Microscopes as Windows on Cells
o Types of Microscopes
o Magnification and Resolution
Categories of Cells
Features of Prokaryotic Cells
Features of Eukaryotic Cells
o Membrane Structure
o Nucleus and Ribosomes
o Endoplasmic Reticulum (ER)
Membrane Structure
• The plasma membrane separates the living cell from its nonliving surroundings
• Phospholipids form an impermeable bilayer
• Proteins provide transport channels and other functions
• Plant cells have rigid cell walls of cellulose
– Provide protection, maintain cell shape, and keep cells from absorbing too much water.
• Animal cells have an extracellular matrix
– Holds cells together in tissues and protects and supports them.
Structures Found Outside the Cell Membrane in Eukaryotes
A Tour of the Cell, Part ICHAPTER 4A Tour of the Cell, Part ICHAPTER 4Microscopes as Windows on Cells
o Types of Microscopes
o Magnification and Resolution
Categories of Cells
Features of Prokaryotic Cells
Features of Eukaryotic Cells
o Membrane Structure
o Nucleus and Ribosomes
o Endoplasmic Reticulum (ER)
Organelles Within A Eukaryotic Cell
The Nucleus: Information Storage and Control of the Cell
• The nucleus is the library of the cell.
• Chromosomes (books) within the nucleus store instructions on how to run the cell
Ribosomes Make Proteins Using Genetic Instructions
Copy of instructionsfrom the nucleus
A Tour of the Cell, Part ICHAPTER 4A Tour of the Cell, Part ICHAPTER 4Microscopes as Windows on Cells
o Types of Microscopes
o Magnification and Resolution
Categories of Cells
Features of Prokaryotic Cells
Features of Eukaryotic Cells
o Membrane Structure
o Nucleus and Ribosomes
o Endoplasmic Reticulum (ER)
The Endomembrane System: Manufacturing and Distributing Cellular Products
• Many of the membranous organelles in the cell belong to the endomembrane system.
The Endoplasmic Reticulum
• The endoplasmic reticulum (ER)
– Lipid synthesis factory, including phospholipids for cell membrane
– Routing system for delivery of proteins (subway system)
A Tour of the Cell, Part ICHAPTER 4A Tour of the Cell, Part ICHAPTER 4Microscopes as Windows on Cells
o Types of Microscopes
o Magnification and Resolution
Categories of Cells
Features of Prokaryotic Cells
Features of Eukaryotic Cells
o Membrane Structure
o Nucleus and Ribosomes
o Endoplasmic Reticulum (ER)