Transcript A Tour of the Cell

“A Tour of the Cell”
Microscopes

Light microscope
 Visible light passes through specimen
 Ocular x objective = magnification
 Up to 1000x
Owen and the microscope
Microscopes

Electron microscopes
 Better resolving
power
 Up to 100,000x
 Scanning EM:
surfaces
 Transmission EM:
internal parts
Kinds of Cells
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Prokaryotic
Eukaryotic
Kinds of Cells
Eukaryotic Cells
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Animal Cell
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Animal vs. plant cells
Cytoplasm: between nucleus &
plasma membrane
Cytosol: fluid portion of cytoplasm
Plant Cell
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Plasma Membrane Structure
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Mostly proteins & lipids
Phospholipids
 Phosphate “head”: water-loving
 Lipid “tail”:
water-fearing
 Form a bilayer
Plasma Membrane Structure
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Proteins
inserted in
bilayer
Fluid mosaic:
phospholipids
& proteins
drift around
Plasma Membrane Function

Selectively permeable
 Only certain materials come in or
go out
 Some “traffic” regulated by
proteins
 Other proteins perform other
functions
Functions of Membrane
Proteins
Nucleus
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Control center
Surrounded by nuclear envelope
 Similar to plasma membrane
Chromatin
 DNA & other proteins
 Chromosome: each fiber of chromatin
 Looks like tangled mess
Nucleolus: ribosome production
Ribosomes
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Not in nucleus
Build cell’s
proteins
Some suspended
in cytosol
Some attached to
endoplasmic
reticulum
Nucleus & Ribosomes
How DNA Controls the Cell
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Transfers coded
message to RNA
RNA carries
message out of
nucleus to rest of
cell
Tells ribosome what
protein to make
Endomembrane System
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Endoplasmic reticulum
Golgi apparatus
Lysosomes
Vacuoles
Endoplasmic Reticulum
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System of tubes &
sacs
Manufactures
molecules
Rough & smooth ER
Rough Endoplasmic Reticulum
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Ribosomes on the outside
Produce 2 types of proteins
 Membrane
 Secretory
Transport
vesicles: bud
from ER
Smooth Endoplasmic Reticulum
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No ribosomes
Synthesis of lipids
 Steroids
 Sex hormones
Detox of drugs
Golgi Apparatus
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Refines, stores & distributes products
Close partnership with ER
Lysosomes
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“Breakdown body”
Sac of digestive enzymes
Destroy harmful bacteria
Recycle parts of damaged organelles
Most plant
cells lack
Lysosomes: Nutrient Digestion
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Food (nutrients) enter cell
Food engulfed by food vacuole
Lysosome fuses with food vacuole
Chemicals in lysosome digest food
Beneficial
products
released
Lysosomal Storage Diseases

Tay-Sachs disease
 Genetic
 Lysosomes lack lipiddigesting enzyme
 Nerve cells accumulate
excess lipids
 Die in childhood
University of AZ
Vacuoles

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Variety of functions
 Storage, transport, etc…
Plants have a large central vacuole
Endomembrane Review
Energy-Converting Organelles

Chloroplasts
 Only in plants &
some protists
 Photosynthesis
Energy-Converting Organelles

Mitochondria
 Cellular respiration
 Energy from food converted to chemical
energy (ATP)
 Almost all
eukaryotic cells
Cytoskeleton
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Fibers that extend through cytoplasm
Provides support
Anchors organelles
Cilia & Flagella
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Extensions of cytoskeleton
Propulsion
Fluid movement
Plant Cell Surfaces
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Cell walls
 Surround plant cells
 Protection, support, prevents cell
from exploding
 Made of???
 Plasmodesmata:
connect adjacent
plant cells
Animal Cell Surfaces
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No cell walls
Extracellular
matrix: holds
cells together
Cell junctions:
connect adjacent
cells