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THE CELL
Cloned sheep (Dolly)
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Major Elements of the HumanBody
Carbon (C) Hydrogen (H) Oxygen (O)
Nitrogen (N)
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Lesser and Trace Elements of theHuman Body
Lesser elements make up 3.9% of thebody and include: Calcium (Ca), phosphorus (P), potassium (K),
sulfur (S), sodium (Na), chlorine (Cl),magnesium (Mg), iodine (I), and iron (Fe)
Trace elements make up less than 0.01%
of the body They are required in minute amounts, andare found as part of enzymes
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Cells: The Living Units
.
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Cell Theory
The cell is the basic structural andfunctional unit of life (Schleiden & Schwann)
Organismal activity depends on individualand collective activity of cells
Biochemical activities of cells are dictated bysubcellular structure
Continuity of life has a cellular basis Virchow expanded on the cell theory and
concluded one living cell could only originatefrom another living cell
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Human cells are microscopic in
size , but they vary considerablyin size and differ even more inshape. For example : flat, brickshaped, threadlike, and irregularshapes.
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1 meter
10 -3
10 -6
10 -9
4.2 Most cells are microscopic, Cells vary in size and shape
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There are two kinds of cells Prokaryotic and Eukaryotic Common features of all cells are a plasma
membrane, DNA, and ribosomes.
4.3 Prokaryotic cells are structurally simpler than eukar yotic cells
Prokaryotic cell
Nucleoidregion
Nucleus
Eukar yotic cell Organelles
C o l o r i z e
d T E M
1 5
, 0 0 0
Figure 4.3A
The two groups (Domains) ofprokaryotic cells are the Bacteria and the Archaea .
Eukaryotic cells are usuallyrelatively larger (10 100 um ormore) in diameter. These cells areinternally complex, with organelles
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Composition of the CELL
Plasma membrane
Cytoplasma Organelles
Nucleus
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Part of the Cell
Plasma membrane: surrounds theentire cell, forming its outer
boundary Cytoplasma: living material insidethe cell (except the nucleus)
Nucleus: this structure containsthe genetic code
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Plasma membrane
It is the membrane that enclosesthe cytoplasm and form the outerboundary of the cell.
This membrane is compose by twolayers of phospolipids, also a fat
molecule called cholesterol (help tostabilize) and proteins (as receptor)
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Plasma Membrane
Figure 3.3
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Functions of Membrane Proteins
Transport Enzymatic activity Receptors for signal
transduction
Figure 3.4.1
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Functions of Membrane Proteins
Figure 3.4.2
Intercellularadhesion
Cell-cellrecognition
Attachment to
cytoskeleton andextracellular matrix
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Passive Membrane Transport:Diffusion
Simple diffusion nonpolar and lipid-soluble substances Diffuse directly through the lipid bilayer
Diffuse through channel proteins
Facilitated diffusion Transport of glucose, amino acids, and ions
Transported substances bind carrier proteinsor pass through protein channels
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Carriers
Are integral transmembrane proteins Show specificity for certain polar molecules
including sugars and amino acids
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Diffusion Through the PlasmaMembrane
Figure 3.7
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Effect of Membrane Permeability onDiffusion and Osmosis
Figure 3.8a
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Effects of Solutions of VaryingTonicity
Isotonic solutions with the same soluteconcentration as that of the cytosol
Hypertonic solutions having greater soluteconcentration than that of the cytosol
Hypotonic solutions having lesser soluteconcentration than that of the cytosol
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Active Transport
Uses ATP to move solutes across amembrane
Requires carrier proteins
Active TransportPLAY
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Cytoplasma
It is the specialized living material of cells It lies between the plasma membrane and
the nucleus Numerous small structure (organelles) are
part of the cytoplasma, along with the fluidthat serves as the interiorenvironment of each cell
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Cytoplasmic Organelles
Specialized cellular compartments Membranous
Mitochondria, lysosomes, endoplasmicreticulum, and Golgi apparatus Nonmembranous
Cytoskeleton, centrioles, andribosomes
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Organelles
Ribosomes Endoplasmic reticulum
Golgi apparatus Mitocondria Lysosomes
Centrioles
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Isolating Organelles by CellFractionation
Cell fractionation takes cells apart and separatesthe major organelles from one another Ultracentrifuges fractionate cells into their
component parts Cell fractionation enables scientists to determine
the functions of organelles
LE 6-5a
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LE 6 5a
Homogenization
Homogenate Tissuecells
Differential centrifugation
LE 6-5b
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LE 6 5b
Pellet rich innuclei andcellular debris
Pellet rich inmitochondria(and chloro-plasts if cellsare from a plant)
Pellet rich inmicrosomes (pieces of plasmamembranes andcells internal membranes) Pellet rich in
ribosomes
150,000 g 3 hr
80,000 g 60 min
20,000 g 20 min
1000 g (1000 times theforce of gravity)
10 min
Supernatant pouredinto next tube
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CELL PART STRUCTURE FUNCTION(S)
PlasmaMembrane Phospholipid bilayerstudded with proteins Serves as the boundaryof the cell. P and C(outer surface) performvarious functions (Ex.markers and receptor)
Ribosomes Tiny particles eachmade up of rRNAsubunits
Synthesize proteins; acells protein factories
EndoplasmicReticulum(ER)
Membranous networkof interconnectedcanals and sacs, somewith ribosome (roughER) and some without(smooth ER)
Rough ER receives andtransports synthesizedproteinsSmooth ER synthesizes
lipids and carbohydrates
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CELL PART STRUCTURE FUNCTION(S)
Golgiapparatus
Stack of flattened,membranous sacs
Chemically processes,then packagessubstances from ER
Mitochondria Membranous capsulecontaining a large,folded membraneencrusted with
enzyme
ATP synthesis; a cellspowerhouse
Lysosomes Bubble of enzymesencased by membrane
A cells digestivesystem
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CELL PART STRUCTURE FUNCTION(S)
Nucleus Double-membraned,spherical envelopecontaining DNAstrands
Dictates proteinsynthesis, therebyplaying and essentialrole in other cellactivities, namely activetransport, metabolism,growth and heredity
Nucleolus Dense region of thenucleus
Plays an essential rolein the formation ofribosomes
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Mitochondria
Figure 3.17
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Mitochondria are the sites of cellular respiration Chloroplasts, found only in plants and algae, are
the sites of photosynthesis Mitochondria and chloroplasts are not part of the
endomembrane system Peroxisomes are oxidative organelles
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Mitochondria: Chemical EnergyConversion
Mitochondria are in nearly all eukaryotic cells They have a smooth outer membrane and an
inner membrane folded into cristae
The inner membrane creates two compartments:intermembrane space and mitochondrial matrix
Some metabolic steps of cellular respiration arecatalyzed in the mitochondrial matrix
Cristae present a large surface area for enzymesthat synthesize ATP
LE 6-17
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Mitochondrion
Intermembrane space
Outermembrane
Innermembrane
Cristae
Matrix
100 nm MitochondrialDNA
Freeribosomesin themitochondrialmatrix
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Endoplasmic Reticulum (ER)
Figure 3.18a and c
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The Endoplasmic Reticulum:Biosynthetic Factory
The endoplasmic reticulum (ER) accounts formore than half of the total membrane in manyeukaryotic cells
The ER membrane is continuous with the nuclearenvelope
There are two distinct regions of ER: Smooth ER, which lacks ribosomes
Rough ER, with ribosomes studding its surface
LE 6-12S th ER
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Ribosomes
Smooth ER
Rough ER
ER lumen Cisternae
Transport vesicle
Smooth ER Rough ER
Transitional ER 200 nm
Nuclearenvelope
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Functions of Smooth ER
The smooth ER Synthesizes lipids Metabolizes carbohydrates
Stores calcium Detoxifies poison
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Functions of Rough ER
The rough ER Has bound ribosomes Produces proteins and membranes, which are
distributed by transport vesicles Is a membrane factory for the cell
G l i A
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Golgi Apparatus
Figure 3.20a
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The Golgi apparatus consists of flattenedmembranous sacs called cisternae
Functions of the Golgiapparatus:
Modifies products of the ERManufactures certain macromoleculesSorts and packages materials into
transport vesicles
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Lysosomes: DigestiveCompartments
A lysosome is a membranous sac of hydrolyticenzymes
Lysosomal enzymes can hydrolyze proteins, fats,
polysaccharides, and nucleic acids Lysosomes also use enzymes to recycle
organelles and macromolecules, a process calledautophagy
Animation: Lysosome Formation
LE 6-14a1 mN l
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Phagocytosis: lysosome digesting food
1 m
Plasmamembrane
Food vacuole
Lysosome
Nucleus
Digestiveenzymes
Digestion Lysosome
Lysosome containsactive hydrolyticenzymes
Food vacuolefuses withlysosome
Hydrolyticenzymes digestfood particles
LE 6-14bLysosome containing
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Autophagy: lysosome breaking downdamaged organelle
1 m
Vesicle containingdamaged mitochondrion
Mitochondrionfragment
Lysosome containingtwo damaged organelles
Digestion
Lysosome
Lysosome fuses withvesicle containingdamaged organelle
Peroxisomefragment
Hydrolytic enzymesdigest organellecomponents
N l
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Nucleus
Contains nuclear envelope, nucleoli,chromatin, and distinct compartments rich inspecific protein sets
Gene-containing control center of the cell Contains the genetic library with blueprints
for nearly all cellular proteins Dictates the kinds and amounts of proteins
to be synthesized
N l li
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Nucleoli
Dark-staining spherical bodies within thenucleus
Site of ribosome production
N l
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Nucleus
Figure 3.28a
THE CYTOSKELETON AND RELATED STRUCTURES
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Microfilaments of actin Enable cells to change shape and move
Intermediate filaments Reinforce the cell and anchor cer tain organelles
Microtubules give the cell rigidity
And provide anchors for organelles and act as tracksfor organelle movement
Actin subunit
Microfilament
7 nm
Fibrous subunits
10 nm
Intermediate filament Microtubule
25 nm
Tubulin subunit
THE CYTOSKELETON AND RELATED STRUCTURES
FUNCTIONAL CATEGORIES OF ORGANELLES
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FUNCTIONAL CATEGORIES OF ORGANELLES
4.19 Eukaryotic organelles comprise fourfunctional categories
Eukar
yotic organelles fall into four functionalgroups Manufacture : synthesis of macromolecules and
transport within the cell. Breakdown : elimination and recycling of cellular
materials. Energy processing : conversion of energy from one
form to another. Support, movement, and communication :
maintenance of cell shape, anchorage andmovement of organelles, and relationships with
extracellular environments All four categories work together as anintegrated team, producing the emergentproperties at the cellular level.
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THE END
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