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Tour Of The Cell
Chapter 6
Microscopy
What is the difference between
magnification and resolving power?
 Magnification is how much larger the
object can now appear
 Resolving power is the ability to
distinguish between two points It is
limited by the wavelength of visible light

The different microscopes


Light microscope - resolving power is limited
by the wavelengths of light
Specimen should be stained, but can be alive
◦ compound microscope
◦ stereomicroscope


Electron microscope - resolving power is
greater since wavelengths of electrons are
smaller than those of light
◦ SEM - 3D image
◦ TEM - flat image
electron microscopes cannot use live specimens
How did
scientists
first discover
the different
cell parts?
As organisms get larger, why do
they become multicellular?
It’s all
about
the
surface
area to
volume
ratio!
Prokaryotic vs. Eukaryotic Cells
Prokaryotic cells
 Bacteria, Archaea
 genetic material not in a
nucleus
 no membrane bound
organelles
Eukaryotic cells
 Protists, Plants, Fungi and
Animals
 true nucleus with genetic
material
 has membrane bound
organelles
The Prokaryotic Cell
The
Plasma
Membrane
General Eukaryotic Cells
Two Areas of the Eukaryotic Cell
What is the space between the cell
membrane and the nucleus called?
 The cytoplasm. This includes the
organelles and the cytosol
 The cytosol is the fluid medium found in
the cytoplasm

The nucleus
Nuclear Components
Envelope = double layered membrane
that has pores for molecular transport
 Chromatin = DNA + protein complex of
threadlike fibers that make up the
eukaryotic chromosome
 Chromosome = Chromatin fibers
condense into visible chromosomes
during cell division

Ribosomes
• Prokaryotic ribosomes differ from eukaryotic ribosomes
• Function = Site of protein synthesis
The Endomembrane system
Related through direct continuity or by
transfer on membrane segments through
vesicles
 Structure of membranes is not identical
 Includes:
 Nuclear envelope --> Endoplasmic
reticulum --> Golgi apparatus -->
lysosomes --> vacuoles -->plasma
membrane

Transport vesicle
from ER
New vesicle
forming
Transport vesicle
from Golgi
Functions of Golgi apparatus
Modifies stores and routes products of
ER
 Alters membrane phospholipids
 Targets products for parts of the cell

Vacuoles
Larger than vesicles
 food vacuoles = formed by phagocytosis
 contractile vacuole = found in fresh
water protozoans, keeps water balance
 central vacuole = found in most plant
cells stores organic compounds, has
enzymes to break macromolecules, has
poisonous and unpalatable compounds,
etc.

Mitochondria and Chloroplasts
not part of endomembrane system
 their membrane proteins are made by
free ribosomes and their own ribosomes
 both have small amount of DNA
 grow and reproduce on their own within
the cell
 involved in energy transformation

Plastids
amyloplasts - store starch, in roots and
tubers
 chromoplasts - non-chlorophyll pigments
responsible for non-green colors
 chloroplasts - chlorophyll containing
plastids

Peroxisome




Contains enzymes that transfer hydrogen
from substrates to oxygen producing
hydrogen peroxide
Some use oxygen to fuel the breakdown of
fatty acids to smaller molecules that can be
used in the mitochondrion
In liver they detoxify alcohol and other
poisons by transferring hydrogen from poison
to oxygen
Hydrogen peroxide is toxic. What enzyme can be
used to break this down?
Cytoskeleton
Provides structural support
 Functions in motility and motion

Microtubules
cellular support
 provides tracks for movement within the
cell: e.g. transport vesicles
 composes cilia and flagella, locomotive
appendages of certain cells
 separation of chromosomes during cell
division (spindle fiber)
 composes centrioles in animal cells

Microfilaments
smaller than microtublues
 participates in muscle contraction
 support
 localized cell contractions

The Cell Surface
cell walls in plant cells
 membrane linked channel plasmodesmata that connects cytoplasm
between cells

Animal Cell Surfaces
glycocalyx - strengthens cell surface, helps
glue animal cells together
 tight junctions - holds cells together to
block transport
 desmosomes - rivets cells together into
strong sheets but permits transport
 gap junctions - analogous to
plasmodesmata in plant cells

Let’s Review
Name the cell structure and its function
 Be able to tell if this structure is found in
prokaryote, eukaryote, plant and/or
animal cells
