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First to View CellsFirst to View CellsIn 1665, Robert

Hooke used a microscope to examine a thin slice of cork (dead plant cell walls)

What he saw looked like small boxes

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First to View CellsFirst to View CellsHooke is responsible

for naming cellsHooke called them

“CELLS” because they looked like the small rooms that monks lived in called Cells

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Anton van LeeuwenhoekIn 1673, Leeuwenhoek

(a Dutch microscope maker), was first to view organism (living things)

Leeuwenhoek used a simple, handheld microscope to view pond water & scrapings from his teeth

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Beginning of the Cell Beginning of the Cell TheoryTheoryIn 1838, a German

botanist named Matthias Schleiden concluded that all plants were made of cells

Schleiden is a cofounder of the cell theory

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Beginning of the Cell TheoryBeginning of the Cell Theory

In 1839, a German zoologist named Theodore Schwann concluded that all animals were made of cells

Schwann also cofounded the cell theory

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Beginning of the Cell TheoryBeginning of the Cell TheoryIn 1855, a German medical

doctor named Rudolph Virchow observed, under the microscope, cells dividing

He reasoned that all cells come from other pre-existing cells by cell division

Cell TheoryCell TheoryCellsCells are the basic living units of organization and function

All cells come from other cellscome from other cellsWork of Schleiden, Schwann, Schleiden, Schwann, and Virchowand Virchow contributed to this theory

Each cell is a microcosm of life

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ENDOSYMBIOTIC THEORYENDOSYMBIOTIC THEORYIn 1970, American biologist, Lynn

Margulis, provided evidence that some organelles within cells were at one time free living cells themselves

Supporting evidence included organelles with their own DNA

Chloroplast and Mitochondria

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Number of CellsNumber of CellsAlthough ALL living things are made of cells,

organisms may be:Unicellular – composed of one cellMulticellular- composed of many cells that may

organize into tissues, etc.

Biological Size and Cell Biological Size and Cell DiversityDiversity

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How Big is a Micron ( µ ) ?How Big is a Micron ( µ ) ?

1 cm = 10,000 microns 1” = 25,000 microns

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Multicellular OrganismsMulticellular OrganismsCells in multicellular organisms often

specialize (take on different shapes & functions)

Cell surface area-to-volume ratioPlasma membrane must be large

enough relative to cell volume to regulate passage of materials

Volume increases faster than surface area so cells must divide

Cell size and shape related to functionEx: Nerve cells, skin cells, sperm cells

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Cell Surface Area-to-Volume Cell Surface Area-to-Volume RatioRatio

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MicroscopesLight microscope (LM)Light microscope (LM), referred to as compoundcompound microscope, used by most students

Two features determine how clearly an object is viewedMagnification-increase in sizeMagnification-increase in sizeResolution-capacity to distinguish fine Resolution-capacity to distinguish fine detailsdetailsWavelength decreases=resolution Wavelength decreases=resolution increasesincreases

Light microscope has 500 times more resolution than human eye

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Electron microscope (EM)Developed in the 1950sAllows study of the ultrastructure of cells

10,000 times more resolution than human eyeBecause electrons have very short wavelengths

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Types of electron microscopeTransmission electron microscope (TEM)TEM)

Used to view internal cell structuresinternal cell structuresSpecimen is embedded in plastic, cut thin, placed on a metal grid and shot with a beam of electrons..

Scanning electron microscope (SEM)SEM)Specimen is coated with gold or other Specimen is coated with gold or other metalmetal

Produces 3-D picture of cell surface3-D picture of cell surface

***Can’t***Can’t be used to view living cellsview living cells

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Comparing light and electron microscopy

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Cell fractionationCell fractionationUsed to isolate & study of organelles

Cells broken apart and the resulting cell extract spun in a centrifuge

Centrifugal force separates extractPelletPellet – heavier cell organelles

Found at the bottom of the tubeSupernatant Supernatant – liquid poured off

lighter particles (dissolved molecules and ions)

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Cell fractionation

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Two Basic Types of CellsProkaryotes: Includes bacteria

(archaeabacteria and Eubacteria)

Eukaryotes: All other known organisms (protists, fungi, plants and animals)

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Prokaryotes – The first CellsProkaryotes – The first Cells

Cells lack a nucleus or membrane-bound organelles

Simplest and smallest type of cellSingle, circular chromosomeMost have a cells wall

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ProkaryotesProkaryotesNucleoid region (center)

contains the DNASurrounded by cell

membrane & cell wall (peptidoglycan)

Contain ribosomes (no membrane) in their cytoplasm to make proteins

Highly organized membrane-enclosed organellesCytoplasm-includes the cytosol (fluid) and the organelles other than the nucleus

Nucleoplasm

Eukaryotes

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DiagraDiagram ofm of

a plant a plant cellcell

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DiagraDiagram ofm ofan an

animal animal cellcell

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The CellThe Cell All Living things are composed of All Living things are composed of cellscells All Cells have/contain the following:All Cells have/contain the following: Cell Membrane - Lipid BilayerCell Membrane - Lipid Bilayer - Separates inside from outside - Separates inside from outside

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Functions of cell or plasma membranesMaintains homeostasisMaintains homeostasisDivides cell into compartmentsDivides cell into compartments,

allowing for specialized activitiesInteracting membranes form

endomembrane systemendomembrane systemVesiclesVesicles transport materials between

compartments (ER Golgi, Golgi plasma membrane…)

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Cell or Plasma MembraneCell or Plasma Membrane

Outsideof cell

Insideof cell(cytoplasm)

Cellmembrane

Proteins

Proteinchannel Lipid bilayer

Carbohydratechains

Composed of double layer of phospholipids and proteins

Surrounds outside of ALL cellsControls what enters or leaves the cellLiving layer

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The Cell Membrane is Fluid

Molecules in cell membranes are constantly moving and changing

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Endomembrane System

Includes nuclear membrane connected to ER connected to cell membrane (transport)

CytoplasmCytoplasmCytoplasmCytoplasm - everything but DNA/Nucleus - everything but DNA/Nucleus

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Major Organelles of the Eukaryotic CellMajor Organelles of the Eukaryotic Cell

The Nucleus “eukaryotic” means “true nucleus”

Contains & protects the cell’s DNA

Helps coordinate the division of cells

Surrounded by a Nuclear EnvelopeEnvelope is double layered with an

Inner & Outer membraneHas perforations called Nuclear

Pores which allow large molecules to pass in/out of the nucleus

Contains a NucleolusRibosomes are made in this

regionContains DNA packaged in

structures called chromosomes ChromosomChromosomeses

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Inside the Nucleus -The genetic material (DNA) is found

DNA is spread out And appears as CHROMATINin non-dividing cells

DNA is condensed & wrapped around proteins forming as CHROMOSOMES in dividing cells

The cellThe cellnucleusnucleus

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Endoplasmic reticulum (ER)Network of folded internal membranes in the

cytosolConnected to Nuclear envelopeNuclear envelopeSmooth ER Smooth ER

Site of lipid synthesislipid synthesisSite of detoxifying enzymesdetoxifying enzymesDetoxifies drugs & alcoholDetoxifies drugs & alcoholStores Ca++ in muscle cellsStores Ca++ in muscle cells

Rough ERRough ERRibosomes on surface manufacture secretory secretory

proteinsproteinsProteins may be moved into the ER lumen (interior)

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EndoplasEndoplasmicmic

reticulum reticulum (ER)(ER)

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RibosomesRibosomesSynthesized by the nucleolusMade of PROTEINS and rRNAContain the enzyme necessary for making

protein bonds (peptide bonds)“Protein factories” for cellJoin amino acids to make proteinsProcess called protein synthesis

Golgi complexCisternae (sacs)Cisternae (sacs) that process, sort, and

modify proteins In animal cellsanimal cells, Golgi complex also

manufactures lysosomes lysosomes GlycoproteinsGlycoproteins

Transported to the ciscis face (receiving side)

Golgi modifies modifies carbohydrates and lipids and packages into vesiclespackages into vesicles that pinch off the trans face pinch off the trans face (shipping side)

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Golgi complex

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Golgi AnimationGolgi Animation

Materials are transported from Rough ER to Golgi to the cell membrane by VESICLES

LysosomeLysosomess

Small Vessicles which serve to digest particles and clean-up cells

Contain Lysozyme – a powerful digestive enzyme

Digests food particles

Destroys worn-out organelles and invading bacteria

Self-Destructs worn-out cells

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PeroxisomesInvolved in lipid metabolism and

detoxificationContain enzymes (catalase) that produce

and degrade hydrogen peroxide H2O2 H2O + O2

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Mitochondria Mitochondria Sites of aerobic respirationaerobic respirationOrganelles enclosed by a double membraneHas its own genome own genomePlays important role in apoptosis apoptosis

(programmed cell death)(programmed cell death)CristaeCristae (internal folds) and matrix matrix

(innermost space) contain enzymes for aerobic respirationNutrients broken down and energy packaged

in ATPATPCarbon dioxide Carbon dioxide and water water by-products

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MitochondrionMitochondrion(plural = mitochondria)(plural = mitochondria)

“Powerhouse” of the cellGenerate cellular energy (ATP)More active cells like muscle

cells have MORE mitochondriaBoth plants & animal cells have

mitochondriaSite of CELLULAR RESPIRATION

(burning glucose)

Mitochondria

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MITOCHONDRIASurrounded by a DOUBLE

membrane

Folded inner membrane called CRISTAE (increases surface areafor more chemical Reactions)

Has its own DNA

Interior called MATRIX

Chloroplasts (Plant Cell Only)Chloroplasts (Plant Cell Only)Cell’s “food” is

generated here.Does this by

photosynthesis - the conversion of CO2, H2O and sunlight into sugar

Contain Chlorophyll - a green pigment - which does this

Has it’s own DNA*Can divide on its

own*n*

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Chloroplasts Plastids that carry out photosynthesisInner membrane of chloroplast encloses the

stroma (gel-like liquid)Contains stacks of interconnected sacs

called thylakoidsStack of thylakoids called granaDuring photosynthesis, chlorophyll traps

light energy (sunlight)Energy converted to chemical energy in ATP

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Chloroplast

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Cellular respiration and photosynthesis

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TheCytoskelet

on

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CytoskeletoCytoskeletonn

Network of fibers which help organize the internal arrangement within cells by providing structural support.

Involved in transport of materialsThree basic types of fibers

compose cytoskeleton:Actin Filaments

Thinnest fibers Formed from protein Actin

Microtubules Largest component of

cytoskeleton Formed from protein Tubulin

Intermediate filaments Intermediate in size and can

vary Form from several proteins

including vimentin & keratin 56

Centrioles(Animal Cell Only)Serve as

construction/organization points for cellular microtubules

Organize and transfer chromosomes and other organelles during Meiosis & Mitosis

Occur in some prokaryotes, protists & animals. Do not occur with fungi and plants

Tube like structures usually at right angles to each other.

Some animals have centriole-like structures at the base of flagella called basal bodies.

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Cilia and flagella Cilia and flagella Thin, movable structures that project

from cell surfaceFunction in movementMicrotublesMicrotubles anchored in cell by basal basal

bodybody

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Cilia & FlagellaCilia & Flagella

Made of protein tubes called microtubules

Microtubules arranged (9 + 2 arrangement)

Function in moving cells, in moving fluids, or in small particles across the cell surface

Glycocalyx (cell coat) Cell coat formed by polysaccarides extending

from plasma membraneProtects the cell Used in cell recognition, adhesion or

communicationMany animal cells are also surrounded by an

extracellular matrix (ECM)Gel of carbohydrates and fibrous proteins

Most bacteria, fungi, and plant cell walls made of carbohydrates

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Extracellular matrixIntegrins- membrane receptors important in cell movementFibronectins- help organize the matrix and help cells attach

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Plantcell walls

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Cell WallCell WallProvides support /

protection for plant cell

Two layers of cell wall Primary Cell

Wall – Outer – Cellulose only

Secondary Cell Wall – Inner – Cellulose & Lignin

Cell membrane is innermost layer

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• Nonliving layer• Found in plants, fungi,

& bacteria• Made of cellulose in

plants• Made of peptidoglycan

in bacteria• Made of chitin in Fungi

Cell wallCell WallCell Wall

TonoplastTonoplast(water vacuole)(water vacuole)(plant cells only)(plant cells only)

Large HLarge H22O / Lipid / O / Lipid /

waste storage tankwaste storage tank Provides pressure Provides pressure

((Turgor pressureTurgor pressure) to ) to maintain cell maintain cell structurestructure

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Plant Cell OrganellesPlant Cell Organelles

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