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Biology:
life study of
What is Life?
Properties of Life
Cellular Structure: the unit of life, one or many
Metabolism: photosynthesis, respiration,
fermentation, digestion, gas exchange,
secretion, excretion, circulation--processing
materials and energy
Growth: cell enlargement, cell number
Movement: intracellular, movement, locomotion
Reproduction: avoid extinction at death
Behavior: short term response to stimuli
Evolution: long term adaptation
Cell Structure
Prokaryotic
before nucleus
Eukaryotic
true nucleus
Antonie van Leeuwenhoek
1632-1723
Developed
microscopes for
observing living
organisms
1674 discovered live
protist cells
1677 discovered
spermatozoa
http://www.ndpteachers.org/perit/Leeuwenhoek.JPG
1682 discovered
striated muscle fibers
http://www.cartage.org.lb/en/themes/Sciences/Physics/Optics/OpticalInst
ruments/Microscope/GlassSphere/usph_01.gif
http://www.molecularexpressions.com/primer/images/introduction/leeuwenhoek.jpg
http://students.ou.edu/J/Renee.E.Jones-1/Van%20leeuwenhoek%20Scope.jpg
http://cell.sio2.be/introduction/images/microleeuw.jpg
Mouth “animalcules” (bacteria) 1684
http://en.citizendium.org/images/thumb/9/94/Leeuwenhoek.jpg/300px-Leeuwenhoek.jpg
http://content.answers.com/main/content/img/scitech/HSmatthi.jpg
http://home.tiscalinet.ch/biografien/images/schwann.jpg
Cell Theory
1839
Theodor Schwann
Prussian Zoologist
1810-1882
Matthias Schleiden
German Botanist
1804-1881
1. All living organisms consist of one or more cells.
2. Some organisms are unicellular, so cells are the fundamental unit of life.
3. New cells come from pre-existing cells by cell division.
We can now add:
4. Cells must show all the properties of life.
5. All cells are basically similar in chemical and structural composition.
Comparing Cell Sizes
Mycoplasma 0.3-0.8 µm
E. coli 1x2 µm
Cyanobacteria 10 µm diam
Plant Cell 30x75 µm
Obviously eukaryotic
Nucleus present
Mitochondrion  Bacterium
Chloroplast  Cyanobacterium
Endosymbiosis: Eukaryotes are Chimeras!
Cell Structure: Boundary
Mycoplasma
Water and enzymes for
fermentation, glycolysis,
Kreb’s cycle, Calvin cycle,
naked circular DNA for
transcription, 70S
ribosomes for translation
cytosol
cell membrane bilayer
glycolipid, sulfolipid
transport proteins
regulates input/output
ETS for PSN, Resp
Gram Positive
Gram Negative
cell wall-murein
peptidoglycan
muramic acid - peptide
prevents dye release
prevents bursting
turgor pressure
penicillin sensitive
additional
membrane bilayer
glyco- sulfo-lipids releases dye
Prokaryotic Cell Shapes
Coccus - cocci
Bacillus - bacillus
Spirillum - spirilli
Vibrio - vibrios
Scanning Electron Microscope (SEM) image..the shape?
http://www.up.ac.za/academic/electron/bacteria.jpg
Ribosomes
This is a cartoon
image created by an
artist to emphasize
certain structures.
Plasmids
Cytoplasm
Flagellum
Chromosome
Plasma
membrane
Cell wall
This is a
transmission
electron microscopy
image that inspired
the cartoon.
Light microscopy
would be even less
detailed!
Figure 7-1 Page 120
This cartoon is not
labeled, so it merely
acts as a key, to orient
the viewer to the
enlarged portion of the
TEM image.
Cytoplasm
Plasma
membrane
Cell wall
Figure 7-2 Page 121
The cytoplasm area
shows the nucleoid
(DNA) area at the top.
The cell membrane
shows that it is a bilayer.
The cell wall shows that
it is multilayered.
DNA
Supercoiled DNA
in chromosome
Figure 7-3 Page 121
This diagram
shows you a
further
enlargement
of a TEM.
The DNA
double helix is
further twisted
to form the
coils you are
seeing here.
Ribosome
Large subunit
of ribosome
Small subunit
of ribosome
Figure 7-4 Page 121
Ribosomes are
70S in “size” in
prokaryotes,
mitochondria, and
plastids.
Those found in the
eukaryotic cytosol
are 80S in “size.”
Cyanobacteria carry out photosynthesis with chlorophyll
bound to proteins in thylakoid membranes
Photosynthetic
membranes
Figure 7-5 Page 122
This is an artificially-colored micrograph from
transmission electron microscopy (TEM)
Cyanobacterial Vegetative Cell (photosynthesis)
cell wall
mesosome
cell membrane
cyanophycean starch
cyanophycin
vacuole
lipid droplet
polyphosphate granule
thylakoids
70S
ribosome
nucleoid
polyhedral body
http://www.botany.hawaii.edu/faculty/webb/BOT311/Cyanobacteria/CBDivideTEM.jpg
Transmission Electron Microscope (TEM) image..the shape?
?
?
http://library.thinkquest.org/3564/Cells/cell91.gif
TEM or SEM? Of Archaeon
Sulfolobus acidocaldarius
Extremophile
Sulfur metabolism
pH 1 to 6
75°C Optimum
Strict aerobe
Partial monolayer (C40)
membranes
Multiple DNA Circles
Introns in DNA
DNA binding proteins
rRNA similarity
RNA synthase similarity
http://web.pdx.edu/~kstedman/MEDIA/Sulfolobus.jpg
Shape?
Operon style regulation
70S ribosomes
TEM or SEM?
Shape?
Bacterium of the Genus: Leptospira
http://phil.cdc.gov/PHIL_Images/02142002/00001/PHIL_138.tif
What are the shapes of these disease bacteria?
http://microbewiki.kenyon.edu/images/a/a8/V_cholerae.jpg
http://www.cab.unimelb.edu.au/images/helico.jpg
Vibrio cholerae
Helicobacter pylori
Are they motile?
If so, by what
mechanism?
Cell Structure: Movement
hook
basal
rings and
rod
anchorage
rotation
directional rotation?
stiff helical flagellum
flagellin protein
is rotated by “motor apparatus”
in the membrane by H+ ATPase
at rates of 200-1700 rps
(>12,000 rpm!)
Taxis:
movement toward stimulus
Exceptions:
myxomycetes, some cyanobacteria use slime, but how?
spirochetes have flexible internal microtubules
(endosymbiotic source of flagella in eukaryotes?)
((gut parasite in termites have spirochete symbiosis))
phototaxis:
movement toward light
chemotaxis:
movement to chemicals
Prokaryotic Growth
• Cells are generally very small
• Cells may double in size but only before
binary fission
• Growth mostly in terms of cell number or
colony size, etc.
• Doubling time in cell numbers may be 20
minutes in ideal conditions
• Could quickly take over the earth if conditions
could remain ideal
• Very competitive in ideal environments
• Ultimate survivors - 3.5 billion years!
Cell Structure: Nucleoid
Nucleoid - genome
one circular DNA molecule
no histone protein
association
attached to cell membrane
transcription by RNA polymerase
replication by DNA polymerase
separation of chromosomes
cytokinesis by furrowing
70S Ribosome
Process called binary fission
rRNA + protein + ribozymes
NOT mitosis!
•Genome and copy are identical
translation of mRNA into protein
•Genome is haploid
•There is no synapsis
•There is no recombination
Cell Associations
Coccus
Diplococcus
Streptococcus - filamentous
Staphylococcus - colonial
?
Streptobacillus
What shapes and associations are shown in these SEMs?
http://www.hhs.gov/asphep/presentation/images/bacteria.jpg
An artificially colored TEM of a cyanobacterium.
Thylakoids contain chlorophyll a (green)
Metabolism?
Association?
Shape?
http://genome.jgi-psf.org/anava/anava.jpg
Anabaena --a cyanobacterium w/ division of labor
Akinete
(hypnospore)
Heterocyst (N2 fixation)
http://www.ac-rennes.fr/pedagogie/svt/photo/microalg/anabaena.jpg
Cyanobacterial Heterocyst (N2 fixation)
cell wall
O2 block
cell membrane
nucleoid
mesosome
ETS for O2
reduction
cytosol
pore in wall
fuel input for
respiration
Nitrogenase
reduces N2
(requires
anaerobic
conditions)
http://www.botany.hawaii.edu/faculty/webb/BOT311/Cyanobacteria/Heterocyst.jpg
Cyanobacterial Akinete (hypnospore)
cell wall
cell membrane
cyanophycean starch
polyhedral body
lipid droplet
polyphosphate granule
vacuole
cyanophycin
thylakoids
nucleoid
http://www.botany.hawaii.edu/faculty/webb/BOT311/Cyanobacteria/AkineteEMBlue400.jpg
Germinating akinetes (producing vegetative filaments)
http://www-cyanosite.bio.purdue.edu/images/lgimages/oreg4.jpg
How do Prokaryotic and Eukaryotic Cells Differ?
Internal
Membranes
Location of DNA and Organelles
Cytoskeleton
Overall Size
Bacteria
and Archaea
In nucleoid
area but may
have plasmids
or replicons
Mesosomes,
thylakoids,
vacuoles
Limited except
in spirochetes
Normally about
size of
mitochondrion
Eukaryotes
In nucleus
surrounded by
envelope,
but also in
mitochondrion,
chloroplast
Large number of
and kinds of
organelles,
endomembrane
system
Extensive
microtubules
and
microfilaments
Most are much
larger than any
prokaryotic cell
Adapted from: Pearson Benjamin Cummings © 2008
Figure 7-5-Table 7-1 Page 122