Discovery of the Cell, Prokaryotes vs. Eukaryotes, and Cell Size

CELLS: PROKARYOTIC VS. EUKARYOTIC Cells have evolved two different architectures: prokaryote “style” eukaryote “style”

1. Prokaryote cells are smaller and “simpler” bacteria range in size, smaller than human cells ( microns in size) single-celled (unicellular) filamentous (strings of single cells) 3

E. coli These prokaryotes are on the head of a steel pin. 4

2. Prokaryote cells are simply built capsule: slimy outer coating cell wall: tougher middle layer cell membrane: delicate inner skin pili: for sticking to things flagellum: for swimming Outside (slide 1 of 2) 5

cytosol: inner liquid DNA: is in one big loop ribosomes: for building proteins 2. Prokaryote cells are simply built Inside (slide 2 of 2) 6

3. Prokaryote lifestyle unicellular: all alone colony: forms a film filamentous: forms a chain of cells 7

4. Prokaryote feeding Autotrophic photosynthetic: energy from sun (ex. cyanobacteria) Heterotrophic disease-causing: feed on living things (parasitic, ex. Staphylococcus aureus) decomposers: feed on dead things (saprotrophic, recycle nutrients in an ecosystem) 8

5. Eukaryotes are bigger and more “complicated” Eukaryotes have membrane-bound organelles have chromosomes unicellular or multicellular include animal and plant cells 9

10 Advantages of each kind of cell architecture ProkaryotesEukaryotes simple and easy to growcan specialize fast reproductionmulticellular very similarcan build large bodies

WHAT IS THE DEAL WITH CELL SIZE? 11

Relative Size 12

LAB ACTIVITY Investigation of Surface Area and Volume

The Discovery of the Cell A historical look into the discovery of the cell 14

1. Robert Hooke English scientist 'Micrographia’ (1665) studied bark/cork – dead cells, opaque studied small invertebrates proposed that plants and fungus had cells 15

2. Anton van Leeuwenhoek Dutch, 1673 Skilled lens grinder improved microscope to 200x “Father of the Modern Microscope” studied: bacteria, protists unicellular organisms, blood, skin, sperm proposed that all animals have cells 16

Development of Cell Theory Between the Hooke/Leuwenhoek discoveries and the mid-19th century, very little cell advancements were made for years. 17

3. Schleiden and Schwann Matthias Schleiden German botanist In 1838 confirmed: ALL PLANTS ARE MADE OF CELLS Theodore Schwann German zoologist In 1839 confirmed: ALL ANIMAL TISSUES ARE MADE OF CELLS 18

4. Rudolf Virchow German physician research in cellular pathology In 1858 confirmed: CELLS MUST ARISE FROM PRE-EXISTING CELLS 19

5. The Cell Theory 1.Cells are the basic unit of life. (Schleiden & Schwann, 1839) 2.All living things are made of cells. (Schleiden & Schwann, 1839) 3.All cells come from pre-existing cells. (Virchow, 1855) The Cell Theory still holds true today. E.coli cells Animal liver cell Plant cell 20

Timeline for the Discovery of Cells 1590 Hans and Zacharias Jansen constructed the first crude compound microscope Robert Hooke looked at a slice of cork under a compound microscope and discovered the cork was made up of small “boxes” that he named cells Anton von Leeuwenhoek and his microscopic creatures that he named “Animalcules.” 1838 Matthias Schleiden studied plant tissue under a microscope and discovered all plants were composed of “cells” Theodor Schwann studied animal tissue under a microscope and found that animals were also composed of cells Rudolph Virchow stated that all living cells come from other living cells. 21

Robert Hooke An English physicist who first saw cells in cork in Anton Van Leeuwenhoek A Dutch businessman who perfected the microscope in Theodor Schwann German zoologist who concluded that all animals are made of cells. Rudolph Virchow German physicist/ pathologist who, in 1855, proposed that all cells come from existing cells. Matthias Schleiden German botanist who determined, in 1838, that all plants are made of cells. 22

6. Modern Cell Theory 1. The cell is structural and functional unit of all living things. 2. All cells come from pre-existing cells by division. 3. Cells contain hereditary information which is passed from cell to cell during cell division. 4. All cells are basically the same in chemical composition. 5. All energy flow (metabolism and biochemistry) of life occurs within cells. 23