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Cell Biology
Outline - Cells
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Cell Theory
Cell Size
Microscopes
Prokaryotic Cells
Eukaryotic Cells
Cell Membranes
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Historical Observations of Cells
Cell Theory
• 1665 - Robert Hooke
Cell Theory
– Describes small rooms in tree bark
• 1838-39 Matt Schleiden & Ted Schann
– All organisms are composed of one or more cells.
– Cells are the smallest living units of all living organisms.
• Late 1800’s Rudolf Virchow’s contribution
– Cells arise only by division of a previously existing cell.
– Life on earth represents a continuous line of descent
1. All organisms are composed of cells.
2. Cells are the smallest living things.
3. Cells arise only from pre-existing cells.
All cells today represent a continuous line of
descent from the first living cells.
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Cell size
Why Are Cells Small?
Small cells have an
optimum surface area to
volume ratio
Surface area to volume ratio Æ
3:1
Light microscopes
resolve structures
200nm apart.
0.3:1
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Electron microscopes
resolve structures 0.2nm
apart.
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Light Microscopes
Microscope Properties
Compound Light Microscope
• Magnification – “enlarge” objects
• Resolution - minimum distance two points can
be distinguished as separate points
Phase Contrast Microscope
67 µm
– Light microscopes
– Electron microscopes
Fluorescence Confocal Microscope
Dark-field Microscope
• Transmission (TEM)
• Scanning (SEM)
• Scanning Tunneling (STEM)
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Views through a microscope - Euglena
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Electron Microscopy
Scanning Electron Microscopy (SEM)
Light microscope
Transmission Electron Microscope
LM 1,000×
SEM
Scanning Electron Microscope
SEM
2,000×
67 µm
ÅLight microscopy
TEM
TEM
2,800×
Transmission
Electron
Microscope
TEM) Image
of
1 Cilium
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Types of Cells
Cell Structure
Prokaryotic
Bacteria
Archaebacteria
All cells have certain structures in common.
1. genetic material – in a nucleoid or nucleus
2. cytoplasm – a semifluid matrix
3. plasma membrane – a phospholipid bilayer
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Eukaryotic
Plants
Animals
Fungi
Protists
4-26 million species
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Prokaryotic Cell Structure
Bacterial Cell Walls
Gram
Positive
Gram
Negative
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Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Prokaryotic Cells - Summary
Cell walls give bacteria different shapes
Simplest organisms – all bacteria
Plasma Membrane – barrier & regulates
™Inside the Plasma Membrane
Cytoplasm
Ribosomes
DNA
Spheres
Rods
™Outside the Plasma Membrane
Cell wall – Peptidoglycan layer(s)
gram-positive or gram-negative
Capsule – Polysaccharide: Adhesion & Hydration
Pili - cell adhesion or DNA transfer
Spirals
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Nucleus
Eukaryotic Cells
Common characteristics
1. Nucleus
Plasma
Membrane
Nucleus
Cytoplasm
2. Cytoplasm
3. Membranes
Form compartments
Separate metabolic activity
Increase surface area
Nucleus
1. Repository of genetic information
2. Synthesis of RNA
for ribosome construction
for protein synthesis
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
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Eukaryotic Cell Structure – Nucleus
Ribosomes
• Ribosomes
– RNA-protein complexes
composed of two subunits
– Site of protein synthesis
– Assembled in nucleoli
Nuclear pores
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Fig. 4.11
Ribosomes and Endoplasmic Reticulum
Rough
endoplasmic
reticulum
Endoplasmic Reticulum
¾Forms compartments
¾Large surface area for metabolism
Rough
endoplasmic
reticulum
¾Rough ER
Protein synthesis by ribosomes
Transport
¾Smooth ER
™Lipid synthesis
™Detoxification
Smooth
endoplasmic
reticulum
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Golgi Apparatus
Endomembrane System
Outgoing Vesicles
Golgi viewed with
fluorescence microscope
Incoming Transport Vesicles
™ Golgi function Æ Collect, package,
and distribute molecules
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Endomembrane System & Lysosomes
Lysosomes
Rough ER
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Lysosomes - membrane-bound digestive vesicles
Transport vesicle
Plasma
membrane
Golgi
apparatus
Lysosomes
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“Food”
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Engulfment
of particle
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Food vacuole
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Digestion
Lysosome animation
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Mitochondrion
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Mitochondrion
Mitochondrion
Exterior and interior membranes
Semi-autonomous
DNA
Ribosomes
Mitochondrion
Outer
membrane
Intermembrane space
Matrix
Inner
membrane
Function: ATP synthesis
Energy
Metabolism
Aerobic
respiration
Cristae
TEM 44,880×
Amoeboid Movement
Cytoskeleton
Cilia and Flagella
Cytoskeleton in action
http://video.google.com/videoplay?docid=5522357274832025243&q=mitosis&total=329&start=0&num=10&
so=0&type=search&plindex=4
http://video.google.com/videoplay?docid=4349197081937999314&q=elodea
&total=23&start=0&num=10&so=0&type=search&plindex=0
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LM 600×
Plasma
membrane
TEM 206,500×
TEM 206,500×
SEM 4,100×
Flagellum
Basal body
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Protein Fibers of the cytoskeleton
Actin and Microfilaments
Network of protein fibers supporting cell shape,
movement and anchoring organelles
Actin Microfilaments
Tubulin subunit
Actin subunit
Fibrous subunits
Microfilaments
Cell shape
Cell movement
25 nm
10 nm
7 nm
Intermediate
filament
Cell shape
Microtubule
Movement Æ organelles,
chromosomes, flagella
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Microtubules
Intermediate Filaments
Intermediate Filaments
Rat epithelial cell
Keratins: Hair & Nails
Cytoskeleton - Summary
• Network of protein fibers
– Shape
– Movement
– anchoring organelles
Microfilaments - made of actin protein
• Cell shape & movement (cell extensions, contractions)
Microtubules - made of tubulin protein
• Organelle & chromosome movement
Intermediate filaments – made of fibrous protein
• Structural stability
Red blood cells
Eukaryotic Cell Structure
Microvilli
Golgi
apparatus
Actin filament
Microtubule
Cytoskeleton
Intermediate
filament
Smooth
endoplasmic
reticulum
Nuclear
envelope
Nucleolus
Plasma
membrane
Centriole
Peroxisome
Lysosome
Ribosomes
Mitochondrion
Rough
endoplasmic
reticulum
Nucleus
Cytoplasm
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Plant Cell
Plant Cell Walls
Central vacuole
Plasmodesmata
Chloroplast
Cell wall
Plasma membrane
Plant Cells - Vacuole
Plant Cells
Chloroplasts
Chloroplast structure
Two external membranes
Internal membranes
DNA
Ribosomes
Function: Photosynthesis
Plant Cell Unique Characteristics
• Central vacuole
– Large compartments in mature plant cells,
– Storage facility for water & other materials
– Produce turgor (pressure) for cell rigidity
End Cells
• Cell wall
– Cellulose & other polysaccharides
– Support of Cells, Tissues, Organs, Whole Plant
• Chloroplasts
– Membranes: 2 in envelope & many internal
– Semiautonomous: DNA & ribosomes
– Photosynthesis
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