What people used to What people used to think:think:

Spontaneous GenerationSpontaneous Generation That living things grew out of non-That living things grew out of non-

living thingsliving things Ex: Maggots grew from rotting meatEx: Maggots grew from rotting meat

Believed for over 2000 years!!Believed for over 2000 years!! Video clip: Video clip: http://http://

www.youtube.com/watch?vwww.youtube.com/watch?v=WNByRghR6sw=WNByRghR6sw

History of Cells & the History of Cells & the Cell TheoryCell Theory

Cell Specialization

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-First to View Cells-First to View Cells In 1665, In 1665, Robert Robert

HookeHooke used a used a microscope to microscope to examine a thin examine a thin slice of slice of corkcork (dead plant cell (dead plant cell walls)walls)

What he saw What he saw looked like small looked like small boxesboxes

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First to View CellsFirst to View Cells Hooke is Hooke is

responsible for responsible for naming cellsnaming cells

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

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Anton van LeeuwenhoekAnton van Leeuwenhoek In 1673, In 1673,

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

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

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Beginning of the Cell TheoryBeginning of the Cell Theory In 1838, a In 1838, a

German German botanist named botanist named Matthias Matthias SchleidenSchleiden concluded that concluded that all all plantsplants were were made of cellsmade of cells

Schleiden is a Schleiden is a cofoundercofounder of of the cell theorythe cell theory

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Beginning of the Cell TheoryBeginning of the Cell Theory In 1839, a In 1839, a

German German zoologist named zoologist named Theodore Theodore SchwannSchwann concluded that concluded that all all animalsanimals were were made of cellsmade of cells

Schwann also Schwann also cofoundedcofounded the the cell theorycell theory

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Beginning of the Cell TheoryBeginning of the Cell Theory In 1855, a German In 1855, a German

medical doctor medical doctor named named Rudolph Rudolph VirchowVirchow observed, observed, under the under the microscope, microscope, cells cells dividingdividing

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

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CELL THEORYCELL THEORY

1.1. All living things are All living things are made of made of cells (one or cells (one or more)more)

2.2. Cells are the basic unit Cells are the basic unit of of structure and structure and functionfunction in an organism in an organism (basic unit of life)(basic unit of life)

3.3. Cells come from the Cells come from the reproduction of existing reproduction of existing cellscells (cell division) (cell division)

Discoveries Discoveries SinceSince the Cell the Cell TheoryTheory

ENDOSYMBIOTIC THEORYENDOSYMBIOTIC THEORY In 1970, American In 1970, American

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

Supporting evidence Supporting evidence included included organelles with organelles with their own DNAtheir own DNA

Chloroplast and Chloroplast and MitochondriaMitochondria

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Cell Size and TypesCell Size and Types Cells, the basic units of organisms, Cells, the basic units of organisms,

can only be can only be observed under observed under microscopemicroscope

Three Basic types of cells include:Three Basic types of cells include:

Animal Cell Plant CellBacterial

Cell

Number of CellsNumber of CellsAlthough Although ALL ALL living things are made of living things are made of

cells, organisms may be:cells, organisms may be: UnicellularUnicellular – – composed of one cellcomposed of one cell MulticellularMulticellular- - composed of many cells composed of many cells

that may organize into tissues, etc.that may organize into tissues, etc.

Cell DiversityCell Diversity Typical cells range from 5 to 50 micrometers Typical cells range from 5 to 50 micrometers

in diameterin diameter Smallest cellSmallest cell Mycoplasma bacteria are Mycoplasma bacteria are

only 0.2 micrometers acrossonly 0.2 micrometers across difficult to see under even the best light difficult to see under even the best light

microscopesmicroscopes Biggest cellBiggest cell Giant amoeba Giant amoeba Chaos chaosChaos chaos

may be 1000 micrometers in diameter may be 1000 micrometers in diameter large enough to be seen with the unaided eye as large enough to be seen with the unaided eye as

a tiny speck in pond watera tiny speck in pond water Despite differences, all cells:Despite differences, all cells:

contain DNA contain DNA are surrounded by a thin, flexible barrier called a are surrounded by a thin, flexible barrier called a

cell membranecell membrane

CELL SIZECELL SIZE

Typical cells range from 5 – 50 micrometers (microns) in Typical cells range from 5 – 50 micrometers (microns) in diameterdiameter

Which Cell Type is Larger?Which Cell Type is Larger?

_________ > _____________ > ___________Plant cell Animal cell bacteria

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

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

Multicellular OrganismsMulticellular Organisms Cells in multicellular organisms Cells in multicellular organisms

often often specializespecialize (take on (take on different shapes & functions)different shapes & functions)

Cell SpecializationCell Specialization Cells in a multi-Cells in a multi-

cellular organism cellular organism become become specialized by specialized by turning different turning different genes on and offgenes on and off

This is known as This is known as DIFFERENTIATIONDIFFERENTIATION

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Specialized Animal CellsSpecialized Animal Cells

Muscle cellsMuscle cells Red blood cells

Cheek cells

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Specialized Plant cellsSpecialized Plant cells

Xylem cellsPollen

Guard Cells

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Cell SizeCell Size

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Prokaryotes include bacteria & lack a nucleus or membrane-bound structures called organelles

Eukaryotes include most other cells & have a nucleus and membrane-bound organelles (plants, fungi, & animals)

Cells May be Prokaryotic or Cells May be Prokaryotic or EukaryoticEukaryotic

Prokaryotes – The first CellsProkaryotes – The first Cells

Cells that Cells that lack a nucleus or lack a nucleus or membrane-bound organellesmembrane-bound organelles

Includes Includes bacteriabacteria Simplest type of cellSimplest type of cell Single, circular chromosomeSingle, circular chromosome

ProkaryotesProkaryotes Nucleoid regionNucleoid region

(center) contains (center) contains the DNAthe DNA

Surrounded by Surrounded by cell cell membrane & cell membrane & cell wallwall (peptidoglycan)(peptidoglycan)

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

EukaryotesEukaryotes

Cells that HAVE Cells that HAVE a a nucleus and nucleus and membrane-bound membrane-bound organellesorganelles

Includes Includes protists, protists, fungi, plants, and fungi, plants, and animalsanimals

More More complexcomplex type of type of cellscells

Eukaryotic CellEukaryotic Cell

Contain 3 basic Contain 3 basic cell structures:cell structures:

NucleusNucleus Cell MembraneCell Membrane Cytoplasm with Cytoplasm with organellesorganelles

Two Main Types of Two Main Types of Eukaryotic CellsEukaryotic Cells

Plant Cell

Animal Cell