Download An Overview of Cells and Cell Research

An Overview of Cells
and Cell Research
1 An Overview of Cells and Cell Research
Chapter Outline
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Model Species and Cell types
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Cell components
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Tools of Cell Biology
Model Species
E. Coli: simplest organism
Yeast: simplest single-cell Eukaryotic organism
Drosophila melanogaster: multi-cell organism
C. Elegans: multi-cell organism
Zebrafish: Vertebrates
Xenopus laevis: Vertebrates
Arabidopsis: model plant species
Mouse:
Human: human genetics
Figure 1.13 Bacterial colonies
Cells as Experimental Models
E. coli
The genome consists of approximately 4.6
million base pairs and contains about 4300
genes.
E. coli divide every 20 minutes.
Useful for bioengineering (producing proteins
and drugs)
Figure 1.14 Electron micrograph of Saccharomyces cerevisiae
Cells as Experimental Models
Yeasts
The genome of Saccharomyces
cerevisiae consists of 12 million base
pairs of DNA and contains about 6000
genes.
Good for genetics manipulation
Useful for gene-gene interaction and
chemical genetics
Figure 1.15 Caenorhabditis elegans
Cells as Experimental Models
The genome of C. elegans contains
approximately 19,000 genes
C. elegans has only 959 somatic cells.
The embryonic origin and lineage of all
the cells has been traced.
Great model for developmental biology
Figure 1.16 Drosophila melanogaster
Cells as Experimental Models
The fruit fly Drosophila melanogaster has
been a crucial model organism in
developmental biology.
Drosophila is easy to grow
Reproduce in about 2 weeks
Figure 1.17 Arabidopsis thaliana
Cells as Experimental Models
A model for plant molecular biology and
development is the small mouse-ear
cress, Arabidopsis thaliana.
It has a small genome and is easily
grown in the lab.
Studies of Arabidopsis have led to the
identification of genes involved in
aspects of plant development, such as
the development of flowers.
Figure 1.18 Eggs of the frog Xenopus laevis
Figure 1.19 Zebrafish
Cells as Experimental Models
Vertebrates are the most complex animals, and the
most difficult to study from the standpoint of cell and
molecular biology.
One approach is to use isolated cells in culture.
Xenopus produces large eggs in large numbers,
facilitating laboratory study and biochemical
analysis. Good for developmental biology
Zebrafish bridge the gap between humans and
simpler invertebrate systems, like C. elegans and
Drosophila.
Figure 1.20 The mouse as a model for human development
Figure 1.7 Evolution of cells
Tools of Cell Biology
The cell theory:
All living systems are made of cells
All cells come from pre-existing cells
All of life’s functions are cellular
The Origin and Evolution of Cells
Two types of cells:
ƒ Prokaryotic (bacteria) lack a nuclear
envelope.
ƒ Eukaryotic have a nucleus that
separates genetic material from
cytoplasm.
Cell types
Animals have five main tissue types:
ƒ Epithelial
cells form sheets that cover
the surface of the body and line
internal organs.
ƒ Skin,
ƒ intestine surface
ƒ Fibroblasts
cells form connective
such as
ƒ bone, cartilage, and adipose
tissue.
The Origin and Evolution of Cells
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Blood contains several different types
of cells:
ƒ Red blood cells (erythrocytes)
function in oxygen transport.
ƒ White blood cells (granulocytes,
monocytes, macrophages, and
lymphocytes) function in
inflammatory reactions and the
immune response.
The Origin and Evolution of Cells
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Nervous tissue is composed of
supporting cells and nerve cells, or
neurons, and various types of
sensory cells.
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Muscle cells are responsible for the
production of force and movement.
Figure 1.12 Light micrographs of representative animal cells
(Part 1)
Figure 1.12 Light micrographs of representative animal cells
(Part 2)
Figure 1.6 Structures of animal and plant cells (1)
Figure 1.6 Structures of animal and plant cells (2)
The Origin and Evolution of Cells
Mitochondria: site of oxidative metabolism.
Chloroplasts: site of photosynthesis.
Lysosomes and peroxisomes: specialized
metabolic compartments for the digestion of
macromolecules and for various oxidative
reactions.
The cytoskeleton is a network of protein
filaments extending throughout the
cytoplasm.
The Origin and Evolution of Cells
The endoplasmic reticulum is a
network of intracellular membranes,
extending from the nuclear membrane
throughout the cytoplasm. It functions
in the processing and transport of
proteins and the synthesis of lipids.
In the Golgi apparatus, proteins are
further processed and sorted for
transport to their final destinations
Tools of Cell Biology
The discovery of cells arose from the
development of the light microscope.
Robert Hooke coined the term “cell”
following his observations of a piece of
cork in 1665.
In the 1670s Antony van Leeuwenhoek
was able to observe a variety of cells,
including sperm, red blood cells, and
bacteria.
Figure 1.22 Numerical aperture
Figure 1.24 Microscopic observation of living cells
Figure 1.25 Video-enhanced differential interference-contrast microscopy
Figure 1.26 Fluorescence microscopy (Part 1)
Figure 1.26 Fluorescence microscopy (Part 2)
Figure 1.30 Confocal microscopy
Figure 1.31 Confocal micrograph of human cells
Figure 1.33 Positive staining
Figure 1.34 Negative staining
Figure 1.37 Scanning electron microscopy
Tools in Cell Biology
Subcellular fractionation with
centrifugation
Cell culture
Use virus to change the genes in
cultured cell
Figure 1.38 Subcellular fractionation (Part 1)
Figure 1.38 Subcellular fractionation (Part 2)
Tools of Cell Biology
In vitro culture systems of plant and
animal cells enable scientists to study
cell growth and differentiation, and
perform genetic manipulations.
Most animal cell types attach and grow
on the plastic surface of dishes used
for cell culture.
Tools of Cell Biology
Embryonic stem cells can be
established in culture and maintain
their ability to differentiate into all of the
cell types of adult organisms.
Embryonic stem cells have played an
important role in studying gene function
in mouse development, and offer the
possibility of treating many human
diseases by transplantation therapies.
Figure 1.41 Culture of animal cells
Figure 1.42 Plant cells in culture