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