:
1. to explain concisely the origin and evolution of cells, the molecular unity underlying their diversity, and characteristics of present-day prokaryotic and eukaryotic cells.
2. to explain the experimental basis of cell biology, the importance of experimental models for research in cell biology; and the features of major model organisms.
3. to describe the major tools of cell biology, which are drawn from microscopy, biochemistry and genetics, and become familiar with relative sizes of cells and organelles, and resolution of microscopes (sizes in nm, um, mm).
4. to appreciate the historical context of experimental cell biology, from the pioneer studies to the current tools.
Important Figures are 1, 3*, 4, 5*, 6*, 7* (22, 24, 26, 28, 29, 30, 32, 36), 38*, 39, 41
Important Tables are 1, 2
Prokaryotic and eukaryotic cells appear descended from a single ancestral type,
3.8 x 10
9
years ago
Early cell was probably a self-replicating RNA molecule in a phospholipid membrane.
(Phospholipid has hydrophobic hydrocarbon tails, hydrophilic phosphate head group)
Cells have diverse patterns of metabolism: ATP is energy currency
glycolysis is most ancient (anaerobic, widespread),
oxidative respiration,
photosynthesis
some prokaryotes use anaerobic respiration
Table 1.1 compares prokaryotes and eukaryotes: Plasma membrane defines cell.
Present-day prokaryotes: small, no separate nucleus compartment;
often have a cell wall (Fig. 1.5)
Eubacteria (domain Bacteria) – phospholipid membrane, ester link
Archaebacteria (domain Archaea) – membrane has ether link
Present day eukaryotes: membrane-enclosed nucleus;
other membrane-bound organelles (Fig. 1.6)
domain Eukarya
unicellular and multicellular
animals, plants, fungi, protists
Molecular evidence suggests Archaea are closer to Eukarya than to Bacteria.
Endosymbiontic theory proposes Bacterial cell
incorporated into early Archaeal cell ->
chloroplast from cyanobacterial ancestor,
mitochondria from aerobic bacterium (Fig. 1.7)

1.
: model organisms facilitate analysis
of fundamental aspects of cell biology (Table 1.2)
Many organisms have had entire their DNA sequence determined (genomes) ->
New field of comparative genomic study
Prokaryotes:
Archaea – Methanococcus jannaschii – methanogen
Halobacterium salinarium - lives in high salt
Bacteria - Escherichia coli – common intestinal bacterium
Mycoplasma – no cell walls, small genome
Bacillus anthracis – anthrax, spore former
Anabaena – cyanobacterium - oxygenic phososynthetic
Eukaryotes: unicellular - Saccharomyces cerevisiae – budding yeast
Dictyostelium discoideum – slime mold
Plasmodium – protozoan causes malaria multicellular – have diversity of cell types (differentiated)
Caenorhabditis elegans – nematode
Drosophila melanogaster – fruit fly
Arabidopsis thaliana – mustard cress
Xenopus laevis – frog (Xenopus tropicalis)
Danio rerio – zebrafish
Mus musculus – mouse
Homo sapiens - human
Viruses can be model systems (non-living) –
They grow in prokaryotic or eukaryotic cells
(Table 1.3 lists typical animal viruses)

:
Light microscopy includes a variety of methods to visualize cells and subcellular structures and to localize specific molecules: resolution has been limited to 0.22 um (220 nm) (Fig. 1.22)
Compare different types of microscopy for limits of resolution, analysis of living vs. fixed cells: bright-field phase-contrast differential interference-contrast fluorescence (Figs. 1.26, 1.27) dye-labeled antibodies
GFP-tagged proteins
FRAP – fluorescence recovery after photobleaching
FRET – fluorescence resonance energy transfer tests protein interactions confocal microscopy reduces out-of-focus emissions two-photon excitation
Electron microscopy increases resolution about 100-fold to 2 nm: transmission EM (positive or negative staining) scanning EM

Subcellular fractionation isolates organelles of eukaryotic cells for biochemical analysis: uses differences in size or density of components (Fig. 1.38)
Differential centrifugation uses different speeds in ultracentrifuge
Density-gradient centrifugation separates materials on dense substances:
velocity centrifugation in sucrose gradient separates proteins, viruses based on size and shape (sedimentation: S values)
equilibrium centrifugation in cesium gradient separates DNA, RNA by
buoyant density (independent of size and shape)
Growth of animal cells in culture (tissue culture) permits experimental manipulations: primary cells cell lines embryonic stem cells stem cells derived from adult cells
Growth of plant cells in culture permits manipulations, regeneration of whole plants
How to study: read the chapter summary; read the chapter in light of the outline, paying attention to bold print terms; focus on concepts and structure-function relationships; be able to explain key figures and experiments
Prepare a summary chart for comparison of major model systems, including: name of organism, domain, genome size (bp), number of chromosomes, cell wall?, types of membrane components, advantages, usefulness of this system (as for study of development), and leave room for additional components during course
Review key terms; questions 1-7 and 10-14 at end of chapter are most relevant.
In addition to textbook questions, consider experimentally how you would follow cellular location of microtubular proteins with a fluorescent antibody versus a GFP-tag.
Also compare the different resolutions of light microscope versus electron microscope; what sub-cellular structures would not be visible in a light microscope?