Transcript Prokaryotic Cells

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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
Prokaryotic Cell Shapes
Coccus - cocci
Bacillus - bacillus
Spirillum - spirilli
Vibrio - vibrios
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 Associations
Unicellular
Coccus
Cells are attached to
each other by
intercellular glue or a
secreted sheath
made of mucilaginous
polysaccharides
Diplococcus
The sheath can provide
antibiotic resistance
too!
Streptococcus - filamentous
Staphylococcus - colonial
?
Streptobacillus
What shapes and associations are shown in these SEMs?
http://www.hhs.gov/asphep/presentation/images/bacteria.jpg
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!
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.
Cell Structure: Boundary
Mycoplasma
cytosol
cell membrane bilayer only…
glycolipid, sulfolipid
transport proteins
regulates input/output
ETS for PSN, Resp
Gram Positive
Gram Negative
cell wall-murein
aka: peptidoglycan
muramic acid - peptide
prevents dye release
prevents bursting
turgor pressure
penicillin sensitive
additional
membrane bilayer
glyco- sulfo-lipids releases dye
Cell Structure: Cytosol
Water and enzymes for
fermentation, glycolysis,
Kreb’s cycle, Calvin
cycle, naked circular DNA
for transcription, 70S
ribosomes for translation
Mycoplasma
cytosol
cell membrane bilayer
glycolipid, sulfolipid
transport proteins
regulates input/output
ETS for PSN, Resp
Gram Positive
Gram Negative
cell wall-murein
aka: peptidoglycan
muramic acid - peptide
prevents dye release
prevents bursting
turgor pressure
penicillin sensitive
additional
membrane bilayer
glyco- sulfo-lipids releases dye
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
Is this example Gram+ or Gram−?
The cytosol area
(labeled
cytoplasm)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.
This is a cartoon
image created by an
artist to emphasize
certain structures.
Cytosol
This is the
transmission electron
microscopy image
that inspired the
cartoon.
Light microscopy
would be even less
detailed!
Figure 7-1 Page 107
These are an SEM (above)
and TEM (below).
The DNA double helix is highly
twisted to form the coils you
are seeing here.
The area inside the cell
including the naked, circular
DNA molecule (lacking DNAbinding proteins) is called the
nucleoid; it is not a nucleus!
The bacterium is prokaryotic
(before-nucleus).
The functions of the nucleoid
are transcription (making
mRNA), and replication
(making a copy of DNA prior to
cell division).
Figure 7-2 Page 108
Ribosome
Large subunit
of ribosome
Small subunit
of ribosome
Figure 7-4 Page 121 (3rd edition: not in current edition!)
Ribosomes are
70S in “size” in
prokaryotes,
mitochondria, and
plastids.
Those found in the
eukaryotic cytosol
are 80S in “size.”
The function of the
ribosome in both
kinds of cells is
translation; the
synthesis of protein
from the
information in
mRNA.
Cell Structure: Nucleoid
Nucleoid - genome
one circular DNA molecule
no histone protein association
attached to cell membrane
mRNA transcription by RNA polymerase
70S Ribosome
rRNA + protein + ribozymes
translation of mRNA into protein
Prokaryotic Growth
• Cells are generally very small
• Cells may double in volume, but only before
binary fission
• Growth is mostly in terms of cell number or
colony size, etc.
• The doubling time in cell numbers may be 20
minutes in ideal conditions
• Bacteria could quickly take over the earth if
conditions could remain ideal
• They are very competitive, but often shed byproducts that inhibit their own survival, so
ideal conditions are usually not sustainable.
• They are ultimate survivors - 3.5 billion years!
Cell Structure: Nucleoid
Nucleoid - genome
one circular DNA molecule
no histone protein
association
attached to cell membrane
DNA replication by DNA polymerase
separation of chromosomes
cytokinesis by furrowing
Process called binary fission
NOT mitosis!
•Genome and copy are identical
•Genome is haploid
•There is no synapsis
•There is no recombination
Transmission Electron Microscope (TEM) image..the shape?
?
?
http://library.thinkquest.org/3564/Cells/cell91.gif
Cyanobacterial Vegetative Cell:
Photosynthesis
Respiration
mesosome
ETS
reactions
cell wall
cell membrane
cyanophycean starch
gas
vacuole
thylakoids
light (ETS)
reactions
70S
ribosome
cyanophycin
lipid droplet
polyphosphate granule
nucleoid
cytosol
Calvin cycle
http://www.botany.hawaii.edu/faculty/webb/BOT311/Cyanobacteria/CBDivideTEM.jpg
sugar synthesis
light
glycolysis CO2 + H2O
O2 + CH2O O2 + CH2O
chlorophyll
Kreb’s cycle
polyhedral body
RuBisCO
CO2 + H2O + energy
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
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!