The cell is the basic unit of life! Life began with the ... · tissues from many species under the...

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1 7-1 Life Is Cellular The Discovery of the Cell Review The cell is the basic unit of life! Life began with the first cell! All living things are composed of cells! Cells make up tissues, organs, organ systems and organisms! Understanding cell structure and function is fundamental to biology! The discovery of the cell as the basic unit of life depended on the invention of the microscope! Nucleus (not all) Cytoplasm (Cytosol + Organelles) Plasma Membrane

Transcript of The cell is the basic unit of life! Life began with the ... · tissues from many species under the...

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7-1 Life Is Cellular The Discovery of the CellReviewThe cell is the basic unit of life!Life began with the first cell!All living things are composed of cells!Cells make up tissues, organs, organ systems and organisms!Understanding cell structure and function is fundamental to biology!

The discovery of the cell as the basic unit of life depended on the invention of the microscope!

Nucleus(not all)Cytoplasm

(Cytosol + Organelles)

Plasma Membrane

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The Discovery of the CellThe scientist to the right is Robert Hooke.The material in the micrograph is cork (tree bark).In 1665, Robert Hooke observed and described cells using a primitive microscope, like the one shown here.  In doing so, he established cytology (the study of cells).

The scientist at right is Anton van Leeuwenhoek.  In 1670, he observed tiny swimming organisms in pond water using his own version of a microscope (above).  In doing so, he established microbiology.  He called them “animalcules”.  Today, we call them microbes.

Early Microscopes

Cork

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The Development Of Cell Theory The Discovery of the Cell

The scientist at right is Matthias Schleiden.  In 1838, he observed plant tissues from many species under the microscope.  He established that all plants (left) are composed of cells. 

The scientist at right is Theodore Schwann.  In 1839, he observed animal tissues from many species under the microscope.  He established that all animals (left) are composed of cells.

The scientist below is Rudolph Virchow.  In 1855 he observed cells dividing under the microscope (below, right).  He established that all cells come from preexisting cells (Omnis cellula e cellula).

Cell Theory1) All living things are composed of cells.2) Cells are the basic unit of structure & function.3) Cells can only come from preexisting cells.

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Exploring the CellTypes Of MicroscopesThe two major classes of microscopes are light and electron.The electron microscope produces 1000x greater resolution and magnification!

The drawback for the electron microscope is that only dead specimens can be viewed because the process to prepare them is lethal.

The micrograph on the left is a highly magnified, 2D view of a cell nucleus captured using a transmission electron microscope (TEM).  The micrograph on the right is a less magnified, 3D view of 2 neurons captured using a scanning electron microscope (SEM).

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5HeLa Cells (Henrietta Lacks, 1951)

Exploring the Cell

The micrograph on the left was produced with a special kind of light microscope called a confocal microscope, which uses lasers to visualize specific cellular structures, like the nuclei and cytoskeletons of these cells!

Types Of Microscopes

The micrograph on the right was produced using a scanning tunneling electron microscope that uses a fine probe to trace the surfaces of samples for magnifications capable of seeing molecules, like this DNA!

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10 m

1 m

Human height

Length of somenerve andmuscle cells

Chicken egg

0.1 m

1 cm

Frog egg1 mm

100 µm

Most plant andanimal cells

10 µmNucleus

1 µm

Most bacteria

Mitochondrion

Smallest bacteria

Viruses100 nm

10 nm

Ribosomes

Proteins

Lipids

1 nmSmall molecules

Atoms0.1 nm

Unaided eye

Light microscope

Electron microscope

How small are cells?Like the hierarchy of biological organization, this chart ranges from atoms to molecules to organelles to cells.

Nanometer= 1 x 10-9 meter

Micrometer (Micron)= 1 x 10-6 meter

Millimeter= 1 x 10-3 meter

Centimeter= 1 x 10-2 meter

Decimeter= 1 x 10-1 meter

MeterThe base unit!

Prokaryotes!

Eukaryotes!

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All living cells have DNA, Ribosomes, Cytoplasm & Plasma Membrane!

Two Major Cell Types

- Evolved ~4bya- 1μm - 10μm- No Membrane-bound Nucleus   or Organelles- Domains: Archaea & Bacteria  Kingdoms: Archaebacteria &                     Eubacteria

Prokaryotes were first and set up the system we all live within!

Prokaryotes

Nucleus

Organelles

Plasma Membrane

Cell Wall

Plant Cell

Eukaryotes

- Evolved ~2bya (Endosymbiosis!)- 10μm - 100μm- Membrane-bound Nucleus  and Organelles- Domain: Eukarya  Kingdoms: Protista                      Fungi                      Plantae                      Animalia

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Prokaryote S & F

“Simple” cells can perform all basic life functions!

E. Coli(Heterotroph,Consumer)

Cyanobacteria(Autotroph,Producer)

Cytoplasm

Ribosomes

Plasma Membrane

Cell Wall Capsule

Nucleoid (DNA)

Mesosome (ER-like) Pili

Plasmid(DNA)

Flagellum

Thylakoid Membrane

All functions will be explained in class!