Transcript Scanning Tunneling Microscope

Chapter 3
Cell Structure
Section 1: Looking at Cells
Section 2: Cell Features
Section 3: : Cell Organelles
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.
Section 1
Looking at Cells
Cells Under the Microscope
•Measuring Cell Structures Scientists use the
metric system to measure the sizes of objects
viewed under a microscope.
•Characteristics of Microscopes Microscopes
enable biologists to examine the details of cell
structure and to understand how organisms
function. Magnification and resolution are two
quantitative characteristics of microscopes.
Section 1
Looking at Cells
Types of Microscopes
•Compound Light Microscope Light microscopes
have a low magnification and can be used to
examine living cells.
•Electron Microscopes Electron microscopes have
a high magnification but cannot be used to examine
living cells.
•Scanning Tunneling Microscope The scanning
tunneling microscope uses a computer to generate a
three-dimensional image of the object.
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.
Section 2
Chemistry of Cells
The Cell Theory
•Cell Theory The cell theory has three parts.
•Cell Size Small cells function more efficiently than
large cells because small cells have a higher
surface-area-to-volume ratio than large cells.
•Common Features of Cells All cells have a cell
membrane, cytoplasm, ribosomes, and DNA.
Section 2
Chemistry of Cells
Prokaryotes
•Prokaryotic Cells Prokaryotic cells lack a nucleus
and other internal compartments.
•Characteristics of Prokaryotes Prokaryotic cells
are surrounded by a cell wall and they have cell
organelles and DNA moving freely within the
cytoplasm.
Section 2
Chemistry of Cells
Eukaryotic Cells
•Eukaryote Cells Eukaryote cells have a nucleus
and other organelles.
•The Cytoskeleton Eukaryote cells have a
cytoskeleton of microscopic protein fibers that
provide the structural framework for the cell and its
organelles. There are three different kinds of
cytoskeleton fibers: actin fibers, microtubules, and
intermediate fibers.
Section 2
Chemistry of Cells
The Cell Membrane
•The Cell Membrane as a Barrier The lipid
bilayer of a cell membrane is made up of a double
layer of phospholipid molecules. The selective
permeability of the cell membrane is mainly due to
the way phospholipids interact in water.
•Membrane Proteins Proteins in cell membranes
include enzymes, receptor proteins, transport
proteins, and cell-surface markers.
Section 3
Cell Organelles
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 structures in plant cells that are
absent from animal cells.
Section 3
Cell Organelles
The Nucleus
•Function of Nucleus The nucleus of a eukaryotic
cell directs the cell's activities and stores DNA.
Section 3
Cell Organelles
Ribosomes and the
Endoplasmic Reticulum
•Production of Proteins In eukaroytic cells, proteins
are manufactured at ribosomes found within the
cytoplasm and found on an internal membrane system
called the rough endoplasmic reticulum (ER).
•Packaging and Distribution of Proteins In eukaroytic
cells, vesicles carry proteins from the rough ER to an
internal membrane system, called the Golgi apparatus, to
be processed. Modified proteins are either released from
vesicles outside the cell or remain in the cell.
Section 3
Cell Organelles
Ribosomes and the
Endoplasmic Reticulum continued
•Lysozymes Some protein containing vesicles remain
in the cell and become lysozymes. Lysozymes digest
and recycle a cell's used components.
Section 3
Cell Organelles
Mitochondria
•Function of Mitochondria Mitochondria
harvest energy from organic compounds to
ATP.
•Mitochondrial DNA Mitochondria have their
own DNA and this allows them to make some of
their own proteins.
Section 3
Cell Organelles
Structure of Plant Cells
•Unique Features of Plant Cells Plant cells
have three structures that animal cells lack: a
cell wall, chloroplasts, and a central vacuole.