5. How did the first cell originate?
• Genetics first:
RNA world
• Metabolism first
• Proteins first
• Membrane first
• Hybrid world
• Intelligent design?
http://pandasthumb.org/archives/2010/02/primordial-soup-1.html
6. Interactive question #1
Intelligent design
is not a scientific
hypothesis
because it is not
A.an educated
guess
B.possible
C.controversial
D.testable
8. …and the first
prokaryotic
cells
(bacteria &
archaea)
• Then lipids &
membranes
• Then cell walls
Martin, W. and M. Russell 2003. On the
origins of cells: a hypothesis for the
evolutionary transitions from abiotic
geochemistry to chemoautotrophic
prokaryotes, and from prokaryotes to
nucleated cells. Phil. Trans. R. Soc.
Lond. B 358: 59–85.
18. Interactive question #2
The definitive difference
between prokaryotic
and eukaryotic cells is
that prokaryotes
A.are smaller
B.are pathogens
C.do not have a nucleus
D.have a cell wall
E.lack internal
membranes
19. Eukaryotic cell section
Yellow & green = cell
membrane and proteins
Blue = proteins
Blue filaments =
cytoskeleton
Pink = ribosomes
Tan = mRNA, tRNA
From: Inside a
Eukaryotic Cell
by David Goodsell
Scripps Institute
http://mgl.scripps.edu/peop
le/goodsell/gallery/patterso
n.html
20. Eukaryotic cell section
Yellow (L) = Golgi apparatus
Yellow (R) = mitochondrion
Blue = proteins
Green = glycosylation
Blue “Buckyball” = coated vesicle
Pink = ribosomes
Tan = mRNA, tRNA
21. Eukaryotic cell section
Yellow = nuclear membrane
Blue = proteins
Orange “spaghetti” = mRNA being
synthesized (R) and then spliced in
nuclear pore (L)
Pink (R) = DNA
22. Origin of eukaryotic cell:
endosymbiosis
fermentation
photosynthesis
respiration
23. Origin of the nucleus:
alternative hypotheses
Martin, W. 2005.
Archaebacteria
(Archaea) and the
origin of the
eukaryotic nucleus.
Current opinion in
microbiology 8(6):
630-637.
24. Origin of the nucleus:
alternative hypothesis
Margulis, L. 2000.
The chimeric
eukaryote: Origin
of the nucleus from
the karyomastigont
in amitochondriate
protists. PNAS
97(13): 6954-6959
25. According to the various
hypotheses, the nucleus
may have evolved from
any of the following
except:
A.A merger of a
community of cells
B.A merger of a liposome
and a chromosome
C.A spore
D.An engulfed cell
E.Infoldings of the cell
Interactive
question #3
26. Cells outline
• What is a cell?
• Types of cells
• Cytoplasm
– Cytosol
– Organelles
– Cytoskeleton
• Cell wall and ECM
– Cell junctions
27. Cytosol
• Water (~70%)
• Ions
• Building blocks ,
nutrients, etc.
• Proteins (>20%)
• Other
macromolecules
• DNA (prokaryotes)
http://en.wikipedia.org/wiki/Cytosol
http://www.scripps.edu/news/scientificreports/sr2008/mb08olson.html
40. Storage plastids
Cazzonelli, C. &
Pogson, B. 2010.
Source to sink:
regulation of
carotenoid
biosynthesis in
plants. Trends in
plant science
15(5): 266-274.
41. Plastids may
function in all of
the following
except
A.photosynthesis
B.fruit ripening
C.food storage
D.cell respiration
Interactive question #4
43. “Organelles” with no membrane
aka macromolecular assemblies
“Organelle” Location Main
features
Function
Pyruvate
dehydrogenase
complex
Replisome
(DNA polymerase)
RNA polymerase
Spliceosome
Ribosome
Fill this table out as we go along…
45. Prokaryotic vs. eukaryotic ribosomes
Melnikov, S.
et al. 2012.
One core,
two shells:
bacterial and
eukaryotic
ribosomes.
Nature
Structural &
Molecular
Biology,
19(6), 560-
567.
Blue = rRNA
Red = protein
Light = conserved
Dark = unique
47. Bacterial cytoskeleton!
The bacterial cytoskeleton. The only cytoskeletal element present in spherical bacteria such as S. aureus (top left) is the tubulin-
like cell division protein FtsZ (green), which localizes in a ring at the onset of cell division, recruits other cell division proteins, and
defines the division plane. Most rod-shaped bacteria (top right) also contain one or more actin-like MreB homologues (red),
which exhibit helix-like localization patterns and are essential for cell width control. At the onset of cell division, the FtsZ ring
forms and defines the division plane. C. crescentus, a vibrioid bacterium (bottom), contains a third cytoskeletal element, the
intermediate filament-like crescentin (blue), which is required for cell curvature and localizes at the inner curvature of cells.
Cabeen, M. &
Jacobs-Wagner, C.
2007. Skin and
bones: the bacterial
cytoskeleton, cell
wall, and cell
morphogenesis.
The Journal of cell
biology, 179(3):
381-387.
