1. Cell Structure and Function
2. Prokaryotic vs. Eukaryotic Cells
Prokaryotic
Bacteria
No nuclear membrane (genetic
material dispersed throughout
cytoplasm)
No membrane-bound organelles
Simple internal structure
Most primitive type of cell
Eukayotic
Many unicellular organisms are
eukaryotic, e.g. paramecia
All cells in multicellular organisms
are eukaryotic.
Nuclear membrane surrounding
genetic material
Numerous membrane-bound
organelles
Complex internal structure
3. Common Features of Cells
http://www.phschool.com/science/biology_pl
ace/biocoach/biokit/chnops.html
Chemical composition – ~24 of the naturally
occurring elements, esp. C, H, N O, P and S
Plasma membrane, cytoplasm, nucleus
4-5. Common Functions of Cells
Obtain nutrients and O2 from the
extracellular environment
Use nutrients and O2 to provide energy for
the cell
Aerobic/cellular respiration
Discharge CO2 and wastes products to the
outside
Synthesize materials necessary for cell
structure, growth, and repairs
Detect and respond to changes in the
internal environment
Move materials within the cell
Maintain differences between intra-and
extracellular fluid by controlling exchange
of material
Reproduce
6. Specialized Functions of Cells
Depend upon the particular type of cell
Modification of a common cell function
Occur in addition to basic functions
Basics = cell survival
Specialized = organism survival
Differences in cell structure allow for
specialized functions
7. Generalized or Composite Cell (Fig.2.14., p. 33)
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8. Basic Regions of a Cell
Plasma membrane
Nucleus
Cytoplasm
http://www.daviddarling.info/images/cell_basic_parts.jpg
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9. Plasma Membrane Functions
Forms cell boundary, enclosing intracellular
contents
Determines composition of the cell
Entry of nutrients
Exit of wastes
Exit of secretory products
Maintain differences in ion concentration
Joins cells together
Ability to respond to environmental signals
10-11. The Plasma Membrane
Determines cell boundaries
Separates intra- and extracellular fluid
Gives cell its form
Intercellular communication
Composition
55% protein
25% phospholipid
13% cholesterol
4% other lipids
3% carbohydrates
Semipermeable
Controls movement of molecules into and
out of cell
12. Extracellular Fluid
Intracellular fluid
Inside cells
~2/3 of total body H2O
Extracellular fluid
Outside of cells
~1/3 of total body H2O
20% of ECF is blood plasma
80% of ECF is interstitial or
tissue fluid
gel-like matrix
13. Plasma Membrane Composition
Phospholipids
Amphipathic
Self-assemble into lipid bilayer
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14. http://kvhs.nbed.nb.ca/gallant/biology/phospholipid_structure.jpg
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15. http://schools-wikipedia.org/images/623/62382.png
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16. http://sleekglobal.com/images/sg0065.jpg
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17. Plasma Membrane Composition
Cholesterol
Stability and fluidity
Membrane proteins
Integral
Peripheral
Carbohydrates
Fluid Mosaic Model
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18. Fig. 2.15, p. 34
19.
http://www.biology.arizona.edu/cell_BIO/problem_sets/membra
nes/graphics/fluid_%20mosaic_model.jpg
20. Membrane Proteins
Integral Proteins
Channels
Leak
Gated
Carriers
Peripheral Proteins
Inner
Docking-marker acceptors
Inner/outer
Enzymes
Outer
Receptors
CAMs
Self-recognition/cell-to-cell
interactions
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21. Carbohydrates
Self-recognition/cell-to-cell interactions
Tissue growth
22. Cell-to-Cell Adhesions
Extracellular matrix
“glue”
Fibrous proteins
Collagen
Elastin
Fibronectin
Carbohydrate gel
CAMs
Specialized cell junctions
23. Desmosomes
Plaque
Fibers
Skin, heart, uterus
24. Tight Junctions
Seal off extracellular space
Impermeable barrier
Epithelium
Selective barriers between
compartments
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25. Gap Junctions
Connexon
Tube of 6 protein subunits
Allow exchange of small water-soluble
particles
Cardiac/smooth muscle
Signaling molecules
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26. Composite Cell
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27. The Nucleus
Largest organized structure
Visible with light microscope
Usually central, round/oval in shape
Control center
Genetic library
Protein czar
Most cells have single nucleus but may be
Multinucleate
Anucleate
28 -29. Nuclear Envelope Fig. 3.15, p. 63
Double membrane
Outer continuous w/ Rough endoplasmic
reticulum
Inner lined w/protein filaments
Layers fuse – pores found at points of
fusion
Encloses nucleoplasm
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30. Nucleoli/Chromatin
Nucleoli
> 1-2 per nucleus
Assembly of subunits of ribosomes
Chromatin
DNA and histones (proteins that
form core for DNA winding)
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31. DNA
Genetic blueprint for cell replication
Directions for protein synthesis
Transcription
Occurs in nucleus
DNA to messenger RNA
mRNA enters cytoplasma
Translation
Occurs in cytoplasm
mRNA to rRNA
tRNA brings in appropriate
amino acids
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32. DNA – Chromosomes
46 total
23 pairs
Seen at the time of cell division
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33. The Cytoplasm
Cellular material between nucleus and
plasma membrane
Organelles – “little organs”
Inclusions (+/-) – chemical substances
stored in cell
Cytosol
Viscous fluid
Water, proteins, salts, sugars
Cytoskeleton
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34. Organelles
Membranous
Provide compartmentalization
Permits incompatible chemical
reactions to occur simultaneously
within the cells
Mitochondria, peroxisomes,
lysosomes, ER, golgi apparatus
Non-membranous
Cytoskeleton, centrioles, ribosomes
35. Endoplasmic Reticulum
Network of fluid-filled tubules
Continuous w/ nuclear membrane
Protein and lipid synthesis
Rough or smooth
36. Rough ER
Flattened sacs
Ribosomes on outer surface
Protein manufacturing
“Membrane factory”
Proteins
Phospholipids
All secreted proteins
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37. Ribosomes
Granules of protein and RNA
Protein synthesis
Free
Globular proteins in cytosol
Membrane bound
Proteins destined for membranes or
for export
38. Smooth ER
Continuous w/ rough ER
Contains enzymes involved in
Lipid metabolism, cholesterol synthesis
Steroid hormone synthesis
Absorption, transport of fats
Detoxification
Glycogen breakdown
Forms transport vesicles
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39-41 . Golgi Complex
http://upload.wikimedia.org/wikipedia/commons/2/25/Nucleus_
ER_golgi.jpg
Series of flattened membranous sacs and
vesicles
Modify, concentrate, and package proteins
and lipids made in RER
Sort and direct finished products to
destinations
Docking markers
Forms secretory vesicles
42-43. Lysosomes / Peroxisomes
Lysosomes
Membranous structures containing
hydrolytic enzymes
Autolysis – self-digestion of cell
Peroxisomes
Membranous sac
Contain enzymes to neutralize free
radicals and perform detoxification
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44. Mitochondria
# & location determined by energy needs
Outer membrane
Inner membrane with cristae
Matrix
Enzymes to carry out cellular respiration
Contain own DNA and RNA; able to
reproduce
45. Vaults
“New”
Octagonal barrels
Hollow
? Cellular trucks carrying cargo from
nucleus to cytoplasm
46. Cytoskeleton
Support network
Rods
Microtubules
Intermediate filaments
Microfilaments
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47-48. Microtubules/Intermediate Filaments
Microtubules
Maintain cell shape
Movement
Transport of vesicles
Distribution of chromosomes
Movement of cilia and flagella
Intermediate filaments
Maintain structural integrity of cell
Resist mechanical stresses
Specialized in specific cell types
Keratin in skin, hair, nails
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49-50. Microfilaments Contractile Systems
Muscle cells
Actin and myosin
Nonmuscle cells
Amoeboid movement
Mechanical Stiffeners
Microvilli
Core of microfilaments
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51. Cytoskeleton
Microtubules
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#/Cell
Structure
Function
Many
Long,
slender
hollow
tubes
composed
of tubulin
Maintain cell
shape and
coordinate
complex cell
movements
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Microfilaments
Many
Intertwined
helical
chains of
actin;also
myosin
Contractile
systems;
mechanical
stiffener for
microvilli
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Intermediate
filaments
Many
Irregular,
thread-like
proteins
Resist
mechanical
stress
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52. Centrosome and Centrioles
Centrosome – region near nucleus
Microtubule organizing center
Centrioles
27 microtubules forming tube
Play role in cell division
53. Cytosol
Semiliquid portion of cytoplasm
Contains organelles and cytoskeleton
Contains enzymes
Intermediary metabolism
Free Ribosomes
Synthesis of cytosol proteins
Inclusions
Fat, glycogen
Secretory vesicles
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