First Microscope Zacharias Janssen – In 1595 He And Father

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First Microscope Zacharias Janssen – in 1595 he and father Hans created the first compound microscope by placing two lens in a tube.

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Robert Hooke Early Discoveries – In 1665 wrote book Micrographia which detailed things he had seen under microscope – In mid 1600’s first person to call a cell a “cell”  Looked at sample of cork, was reminded of monk’s cell, or room – Also further developed Janssen’s microscope into more practical device

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Early Discoveries

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Anton van Leeuwenhoek – In late 1600’s observed sperm, microorganisms – 1st person to observe single celled organisms in pond water – Used hand lenses (magnifying glasses) which he made – Made first accurate description of red blood cells 1820s - Robert Brown observed/named nucleus in plant cells

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Early Discoveries •

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Mathias Schleiden & Theodor Schwann – In 1838 Schleiden recognized that all plants are made up of cells. – In 1839 Schwann recognized that all animals are made up of cells – Together the two articulated the cell theory Rudolf Virchow – In 1855 Virchow proposed that all cells come from existing cells. – This provided the last piece of the cell theory Video Clip

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Cell Theory •

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All organisms are composed of one or more cells. Cells are the smallest living units of all living organisms. Cells arise only by division of a previously existing cell.

BrainPop on Cells, login & password: masonhs

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Create detailed images of something that is otherwise too small to see Light microscopes –

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Microscopes

Simple or compound

Electron microscopes –

Transmission EM 

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Scanning EM 

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electrons transmitted through specimen electrons beamed onto surface of the specimen

They have better Resolution 

minimum distance two points can be apart and still be distinguished as two separate points 7

Comparison between Microscopes light microscope

source of light

specimen

light

living(moving)/nonliving

TEM

SEM

electrons

electrons

nonliving

nonliving

max resolution

200 nm

max magnify

1,500x

250,000x

100,000x

colored dye

heavy metal

coated C, Au

stains type of image

colored

1 nm

black/white

BrainPop on Microscopes, Login & Password: masonhs

10 nm

black/white 8

What type of microscope was used for each image? animal cell EM

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Light Microscopy •

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Wavelengths of light are 400-750 nm

ocular lens

prism

If a structure is less than one-half of a wavelength objective lens long, it will not be stage visible condenser

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Light microscopes can resolve objects down to about 200 nm in size

illuminator

source of illumination 10

Electron Microscopy accelerated electron flow (top to bottom) •

Uses streams of accelerated electrons rather than light

condenser lens specimen objective lens

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Electrons are focused by magnets rather than glass lenses Can resolve structures down to 0.5 nm You Tube Video Clip

intermediate lens projector lens

viewing screen 11

Visualizing Cells

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Cell Characteristics/Groups

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All cells start out life with: – cell membrane  a thin, flexible barrier around the cell – Cytoplasm  material inside the cell membrane – Ribosomes  location of protein synthesis – DNA  Genetic instructions for making proteins Two major types of cells: – Prokaryotic – Eukaryotic

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Common name: – BACTERIA Archaebacteria and Eubacteria DNA is not enclosed in nucleus Generally the smallest, simplest cells No organelles except ribosomes

Prokaryotic Cells

Video Clip

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Pili •Helps connect cell to other cells, aids in movement Plasma Membrane

Slime

•Protection & helps cell stick to surfaces

Plasmid •Circular ring of DNA

•Strands of DNA •Increases surface area for cell respiration •Helps form cell walls

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Know the functions of all these parts of a Prokaryotic Cell

Eukaryotic Cells •

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Have a nucleus and many other organelles Complex – many cell parts – Learn the structure/function of the parts in the chart provided in class Eukaryotic organisms have Eukaryotic cells: – Plants – Animals – Protists – Fungi BrainPop on Cell Types Login & Password: masonhs

Video Clip

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