Chapter 7
Cellular Structure and Function
CELLS!
Chapter 7.1
Cell Discovery and Theory
Robert Hooke observes the structures of
cork (oak bark) and calls the units cells.
History of Cell Theory
What did Anton Van Leeuwenhoek see through his microscope?
He was surprised to find what looked like tiny animals.
He named these animals “animalcules”.
How do you develop a theory?
Cell Theory
1. All living organisms are composed of one or
more cells.
2. Cells are the basic unit of structure and
organization of all living organisms.
3. Cells arise only from previously existing cells,
with cells passing copies of their genetic
material on to their daughter cells.
Microscopes
Review Figure 7.1 on page 182-183,
Microscopes in Focus
Why were there long periods between significant
discoveries about cells?
How Big?
http://www.cellsalive.com/howbig.htm
Types of Microscopes
1. Compound Light Microscopes
2. Electron Microscopes
a. Transmission Electron Microscope
b. Scanning Electron Microscope
c. Scanning Tunneling Electron Microscope
Based on the names of these microscopes, how do
you think each type magnifies objects?
Compound Light Microscope
• Uses series of glass
lenses and visible light
to produce a magnified
image
• Specimens must be thin
• Specimens can be alive
or dead
• Maximum
magnification is 1000x
Compound Light Microscope
Calculating Total Magnification
• Compound light microscopes use a series of
lenses to magnify; each lens magnifies the image
• For example, if eyepiece lens magnifies at 10x
and the objective lens magnifies at 10x, the total
magnification is 100x (10 X 10)
What would the total magnification be if the
eyepiece magnified at 10x and the objective lens
magnified at 4x?
Answer = 40 x = 10 X 4
Helpful Hints:
• Diaphragm Usage
• Course Adjustor v. Fine Adjustor
– Location and purpose
– Movement of stage
• Lowest power to highest power!
– DON’T USE COURSE ADJUSTOR IN HIGH POWER!
Compound Light Microscope
Microscope Part
Ocular (eyepiece)
Nosepiece
High Power Objective Lens
Low Power Objective Lens
Stage and Stage Clips
Diaphragm
Fine Adjustment
Course Adjustment
Base/Arm
Function
Compound Light Microscope
Microscope Part
Function
Ocular (eyepiece)
Used for viewing object; hold lens with 10x magnification
Nosepiece
Holds objective lens
High Power Objective Lens
Lenses with magnification of 10x, 40x, 100x, or more
Low Power Objective Lens
Lens with magnification of 4x
Stage and Stage Clips
Hold microscope slide in place
Diaphragm
Controls the light entering the field of view
Fine Adjustment
Brings object into sharp focus
Course Adjustment
Brings object into focus
Base/Arm
Support for the microscope
Electron Microscopes –
Uses beams of electrons to magnify images
Transmission Electron
Microscope (TEM)
• Aim a beam of electrons at
a thin slice of cells
• Electrons are passed
through a specimen to a
screen
• Thick parts of the
specimen absorb more
electrons than thin parts
forming a black-and-white
shaded image of specimen
• Can magnify up to
500,000x
• Specimen must be dead,
sliced thin, and stained
Scanning Electron
Microscope (SEM)
• Directs electrons over the
surface of the specimen
• produces a three
dimensional image
• Specimen must be
nonliving
Scanning Tunneling Electron
Microscope (STM)
• Brings a charged tip of a
probe extremely close to
the specimen so that the
electrons “tunnel” through
the small gap between
• Creates a threedimensional image
• Can use live specimens
Transmission Electron
Microscope (TEM)
Scanning Electron
Microscope (SEM)
Scanning Tunneling Electron
Microscope (STM)
Transmission Electron Microscope
Bacteriophages (viruses that infect bacteria)
Scanning Electron Microscope
Human atrial (heart) muscle
Scanning Electron Microscopy
Stainless
Steel
Screen
Scanning Electron Miscroscopy
Table
Salt
Scanning Electron Miscroscopy
Insect on the
leg of a
daddy longleg spider
Scanning Electron Miscroscopy
Eye of an
Ant
Scanning Electron Miscroscopy
Spider
Scanning Tunneling Microscope
STM of DNA molecule
Quiz Tomorrow
• History of Cell Theory
– Hooke and Van Leeuwenhoek
• Cell Theory
• Types of Microscopes
– Electron Microscopes
– Compound Light Microscopes
• Parts
• Functions
• Calculating total magnification
• (NOT Basic Cell Types)
Basic Cell Types
• What do all cells have in common?
– Plasma Membrane (barrier controls what moves in
and out of cell)
– Genetic material
Basic Cell Types
Prokaryotic Cells
Eukaryotic Cells
• Smaller
• Larger
• Contain no organelles
• Contain membrane-bound
organelles – specialized structures
that carry out specific cell functions
• No nucleus
• Contain nucleus to hold genetic
material
• Bacteria
• Protists, Fungi, Plants, and Animals
Prokaryotic Cells
Eukaryotic Cells
• http://www.arsmachina.com/hooke.htm
• http://www.nndb.com/people/356/00008709
5/
• http://www.kidsbiology.com/biology_basics/c
ells_tissues_organs/cell_history_discovery4.p
hp
• http://nzforu.com/tag/a-transmissionelectron-microscope-tem/
Chapter 7.2
http://www.youtube.com/watch?v=Qqsf_UJcfBc
Function of Plasma Membrane
• Thin, flexible boundary between the cell and
its environment
• Maintains homeostasis by controlling what
enters and exits the cell
– Allows nutrients to enter
– Allows waste and other products to leave
Selective Permeability
• The plasma membrane allows some
substances to pass through while keeping
others out
• Controls how, when, and how much of these
substances enter and leave a cell
Structure of the Plasma Membrane
• Most molecules in the membrane are
lipids
– Phospholipids containing
• Glycerol
• 2 fatty acids
• Phosphate group
Phospholipids
Structure of Plasma Membrane
Structure of the Membrane
• “Phospholipid bilayer”
– TWO layers of
phospholipids
– Interior is hydrophobic
(water fearing)
• Non-polar fatty acid tails
– Exterior is hydrophilic
(water loving), polar
• Polar phosphate groups
 Phospholipids are arranged in a bilayer.
© Glencoe Biology 2007
 hydrophilic (polar) heads are on the outside
 hydrophobic (nonpolar) tails are on the inside
 Proteins are imbedded in the membrane.
 Transmit signals to the inside of the cell.
 Anchor the membrane to the internal support structure of the cell.
 Transport proteins act as tunnels for substances to enter and
leave the cell.
 Cholesterol prevents fatty acid
tails from sticking together.
 Carbohydrates attach to the
proteins.
 Identify the cell
 Identify chemical signals in the
cell’s environment.
© Glencoe Biology 2007
“Fluid Mosaic Model”
•
Phospholipids move sideways
• Other molecules float in the
phospholipids like apples bobbing
in a barrel of water
Chapter 7.3
Cell Structures and Organelles
Cell Organelles
Cell Part
Function
Cytoplasm
Semfluid material that surrounds the organelles and
provides a place for chemical reactions to take place.
Cytoskeleton
A network of long, thin protein fibers that form a
framework and support system for the cell; anchors all the
organelles
Nucleus
Control center of the cell; contains the cell’s DNA;
surrounded by nuclear membrane (envelope)
Ribosomes
Produces proteins
Nucleolus
Produces ribosomes
Endoplasmic reticulum
Folded membrane system that is the site for protein and
lipid production
Smooth ER
Area with no ribosomes attached; place where many
carbohydrates and lipids are produced
Rough ER
Ribosomes are attached and produce proteins
Cell Organelles
Cell Part
Function
Golgi Apparatus
Flattened membranes that modified, sorts, and packages
proteins
Vacuoles
Temporary storage for the cell; used to store food, enzymes, and
other materials needed for the cell
Lysosomes
Structure containing enzymes used to digest waste
Centrioles
Used in cell reproduction
Mitochondria
Produce energy by breaking down sugars
Chloroplasts
Capture light energy and convert it to chemical energy (food);
found in plant cells
Cell wall
Thick, rigid fibers that surround the plasma membrane and
protects the cell
Cilia and Flagella
Used for cell movement in some eukaryotic cells
Chapter 7 Test
• History of Cell Theory
– Hooke
– Leeuwenhoek
– Cell theory
• Microscopes
– Light microscopes
– Electron microscopes
• Prokaryotic & eukaryotic cells
• Plasma membrane
– Selective permeability
– Phospholipid bilayer
• Cell Organelles Function