-
Cell Types
:
Prokaryotes vs.
Eukaryotes
Definition of a cell ....
Concept
Activity - Chapter 1.1 (6.2) -
Comparing Prokaryotes & Eukaryotes
- A living
CELL is a .....
- self contained,
self assembling,
- self adjusting,
self perpetuating,
- isothermal mix of
biomolecules,
|
 |
-
held in a 3-D
conformation by weak non-covalent forces,
which extract raw materials (precursors) & free energy
from surroundings,
that catalyzes reactions with specific biocatalysts
(enzymes), that it makes,
-
and which shows great
efficiency & economy of metabolic regulation,
and that maintains a dynamic steady state far from equilibrium,
and which can self-replicate using
the informational molecule DNA.
|
-
-
...
using rRNA sequence analysis as an evolutionary measure, 3 Biological
Domains of
life...
Eubacteria, Archaea
(extremophiles), and
Eucarya were defined
domains
are based upon difference in nucleotide sequences in
rRNA [Phylogeny]
-
-
...Cell Organization
[structure]
3 Basic Parts of a Cell
-
1. membrane (selectively permeable - in/out)
-
2. a DNA region (nucleoid or nucleus)
-
3. the cytoplasm & its subcell parts:
organelles
-
-
-
-
-
-
- ...but, all cells are divisible into only 2 successful Cellular Plans of Organization
distinguished primarily by
size & type of internal
structure (organelles)
Prokaryotes... Gk
πρό- (pro-) "before"
+ καρυόν (karyon)
"kernel
= nucleus"
today's prokaryotes includes:
blue green algae
&
bacteria... [bad
puns
& jokes]
-
primitive, simple, versatile, ubiquitous, unicellular
life form
a most successful life form-
80% to 90% of total biomass of planet
over 2,500 different species known
(easily cultured
in lab)
some
characteristic parts*
&
an E.M. pic of
E. coli*
lack complex membrane bound organelles (but, some
have
specialized membranes*)
genes
are
"naked DNA" - i.e., no protein
complexes & no real "chromosome?"
little to no internal compartmentation (organelles)
figure
size range - 0.1 to 10 µm diameter size
relationships*
current paradigm is that eukaryotes evolved from simpler prokaryotes
Chapter 6.2 -
Prokaryotic Cell Structure & Function.
-
Procaryotes...
includes all the unicellular
that form the TWO Domains :
the
Archaea (Archaea bacteria) &
the bacteria (Eubacteria = cynaobacteria, mycoplasma, & rickettsiae).
µ
the procaryotes - archaeans/eubacteria
evolved to solve environmental challenges (problems)
via their
versatile chemistry - they evolved new metabolic solutions...
...they are are
highly conserved - "living fossil forms"
ARCHAEA BACTERIA -
many living archaea bacteria are called
Extremophiles:
organisms that thrives
in physical or geochemical
extreme conditions that are
detrimental to the majority of life on Earth;
ACIDOPHILES...
Sulfolobus acidocaldaries - acid loving microbes pH < 5,
sulfur springs
ALKALIPHILES...
Natranobacterium gregoryi
- pH > 9, live in
soda lakes
HALOPHILES...
Halferax volcanii
- salt loving, live in Dead Sea
&
Great Salt Lake
METHANOGENS..
methanobacterium
CO2
+ H2 --> CH4
[Oregon
culture collection]
PSYCHROPHILES..
Polaromonas vacuolata
- cold loving - live in
antarctic ice & seas
THERMOPHILES... heat loving, in acid
hot springs, deep ocean geysers [YNP]
|
there is a combination of eukaryote & prokaryote traits in the
Archaea
|
|
some key differences between
ARCHAEA and
BACTERIA* include -->
fig-1
&
fig-2 |
EUBACTERIA...
[
images ]- includes all the other living bacteria [except
the archae]-
i.e., "the modern forms"
human gut holds about
1,000 different bacterial species & some
10 trillion bacterial cells total
most exhibit 3 common shapes
bacterial shapes: cocci, bacillus, spirochetes
-
shapes
of bacteria* (pics
on pin &
syringe &
staph) often possess
flagella for motility
a picture
can
be distinguished by
Gram Staining*
of cell wall components
several eubacteria are
pathogenic and may
cause diseases: [table]
including:
- Nobel Prizes have been awarded for research
on the immune responses to pathogenically harmful bacteria,
yet, of 300,000 species (maybe millions more), only 170 species are known to
be pathogenic in mammals, as...
-
Bacillis anthracis = anthrax
(spores
EM pics)
Clostridium botulinum =
botulism
Staphylococcus
aureus =
sepsis,
endocarditis, & nosocomial infections
Salmonella (pic) = food poisoning &
typhoid
- many
eubacteria make
antibiotics:
(history
of antibiotics)
-
Streptomyces
=
streptomycin
(1943)
Penicillus*
=
penicillin
(1928 -
pics)
also includes
CYANOBACTERIA [description]
- are photosynthetic eubacteria (pics)
with cytoplasmic membranes;
also catalyze N2 fixation [N2
--> NH3,NO2-,
NO3-]for aa's
Martian analogs
- extremophile environments, microbes, & Mars habitats.
-
- EUKARYOTIC [Gk: eu -true
karyon
-nucleus...] cell plan of
multi-cellular organisms,
- eukaryotes (eukarya) include the
fungi, algae,
protozoa, slime molds, & all
plants & animals,
contain many internal membrane bounded
organelles...
organelle
- a subcell part that has a distinct metabolic function
-
7 Major CHARACTERISTIC of EUCARYOTES:
have a nucleus - single greatest step in evolution of higher
organismal cells
genes in "chromosomes" [colored bodies...
made of DNA + proteins]
contains more DNA (1,000x more) than
prokaryotes
presence of
organelles - significant internal compartmentalization of function
presence of
flexible cell "walls"
(extra-cellular matrix) - allows phagocytosis
presence of
cytoskeleton
- provides internal framework; favors larger cells
extensive
internal membranes
reproduce
sexually
usually
larger - cell
volume 10X > than bacteria
- size 5.0 to 20 µm diameter
-
2 major kinds
of eukaryotic cells
-
- animal -
metazoan cell* - heterotrophic
feeder
- plant -
metaphytian
cell* - autotrophic producer
contain chloroplasts, large vacuoles, cellulosic cell wall
Concept Activity -
6.2 -
Build an Animal Cell and a Plant Cell
-
Concept Activity - 6.7
- Review of
Animal Cell
structure & function
-
Concept Activity - 6.7
- Review of
Plant
cell structure and function
-
- Procaryotes vs. Eucaryotes
-
table of
similarities & differences*(later)
Concept Activity - 6.2
-
Comparing Prokaryotes & Eukaryotes.
-
Identification of subcell parts
- magnification = how much larger objects appear - typically
1,000 fold
[ scale of biological parts*
]
-
resolution = distance between objects: allows one to distinguish 2 dots =
0.2 µm (200nm)
[
resolvable size scale*
]
killing/fixing of samples : formaldehyde & glutaraldehyde
denature all proteins
embedding & sectioning :
by a
microtome (1 to
10 µm thick tissue sections)
selective
staining :
stains (dyes) attach to specific molecules
colorizing them (pic1* & pic2*)
| TYPES of LIGHT MICROSCOPY:
unstained and living |
 |
Brightfield Microscopy:
Standard transmission of light through a living cell has very little contrast.
A cell is 70% water, thus most of the cell is basically colorless and translucent, i.e.,
invisible to the eye. |
 |
 |
Phase Contrast Microscopy:
Incident light [iL] is out of phase with
transmitted light [tL] and when the phases of the light are synchronized by
an interference lens, a new image with good contrast is seen. |
 |
 |
Nomarski (phase-contrast):
is also known as differential interference contrast microscopy.
The different phases of incident and transmitted light
are synced by a set
of special condenser lens mounted below the stage of a microscope. |
 |
 |
Dark Field Microscopy:
Here the illuminating rays of light are directed from the side so that
only scattered light enters the microscope lenses, consequently the cell
appears as an
illuminated object against the view. |
|
|
| |
TYPES of LIGHT MICROSCOPY:
with killed, fixed, and stained samples |
 |
a thin
section of human pancreas stained with a mixture of Eosin and
Hematoxylin viewed with a didymium filter inserted into the light path.
|
 |
A fluorescence
microscope is a light microscope that views emitted fluorescent light
from a fluorophore (as
GFP) bound to a cellular molecule.
Fluorescence microscopy of endothelial cells using three labels.
Red lables the mitochondria,
green lables the F-actin cytoskeleton and
blue lables the nucleus.
Image by Steve Karl - Olympus BX Fluorescence Microscopy. Taken with the
Meade Deep Sky Imager.
|
 |
Confocal
microscopy is a form of fluorescent microscopy, but instead of flooding
an
entire cell sample with light to excite the
fluorophore, which results a blurred image,
a pinpoint (laser) light source is used to excite the
fluorophore resulting in enhanced
contrast (images*).
By
Dr. Sonja Pyott, U. North Carolina, Wilmington, specimen: Cochlea
and Hair Cells.
Laser confocal microscopy can produced some
stunning
images*.
Olympus Bioscapes Microscopy Gallery
|
Identification of
subcell parts continued........
2.
Electron Microscopy
A primer on Electron Microscopy (pic
of TEM scope 4.1)*
George Palade - pioneered use of EM for cells structure studies
resolution = 0.2 nm specimen preparation*
image
analysis... 3D restructuring of images*? analogy =
Orange Bowl*-
LandShark
-
three types
of electron microscopy:
-
TEM - Transmission: a TEM picture*
SEM - Scanning:
prep* &
TEM vs. SEM
pic's &
see
some examples
FEM - Freeze Fracture:
how to prepare*,
results*, &
FEM
picture*
3.
Cell Isolation & Tissue Culture... Model Experimental Systems.
RBC cells
&
HeLa
cells*
(G.Gey)
&
how to culture HeLa cells
-
- 4.
Cell Fractionation*
&
Differential Centrifugation* leads
to organelle
separations
- 5.
Size relationships - see
text figures*
[fun stuff:
Powers of 10
and
Images & Scaling]
Case
Studies - Process of Science - Chapter 7 - Size Relationships
The major
eucaryotic organelles [ex:
epithelial cells]
NUCLEUS
: envelope, pore, chromatin, nucleolus, nucleoplasm
MITOCHONDRIA : peri-mitochondrial space, cristae,
mitoplasm (matrix)
CHLOROPLAST : peri-chloroplast space, thylakoids,
chloroplasm (stroma)
RIBOSOME : small subunit, large subunit, polysome
ENDOPLASMIC
RETICULUM : smooth &
rough
GOLGI BODY : sided: cis & trans; endomembrane
pathway
LYSOSOME : hydrolytic enzymes
MICROBODIES : peroxisome & glyoxysome
CYTOSKELETON : microfilaments, microtubules,
intermediate filaments
CENTROSOME : centriole, basal body, flagella, cilia
INTERCELLULAR
JUNCTIONS : tight junctions, desmosomes,
gap junctions, plasmodesma
PLANT CELL
VACUOLE : tonoplast, cellular waste, and
osmoregulation
CELL MEMBRANE : selective
transport barrier.
GRAM Stain...
a method for differential staining of bacteria:
smears are fixed, stained in a solution of
crystal violet and treated with
iodine solution, rinsed, decolorized, and then counter-stained
with safranin O;
Gram staining is
useful in bacterial taxonomy and identification,
back and also in indicating fundamental differences in
cell wall structure*.
|
