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 (10-100 microns in size)

• single-celled (unicellular)

• filamentous (strings of single cells)

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E. coli

These prokaryotes are

on the head of a steel pin.

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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)

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cytosol: inner liquid

DNA: is in one big loop

ribosomes: for building proteins

2. Prokaryote cells are simply

built

Inside (slide 2 of 2)

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3. Prokaryote lifestyle

unicellular: all alone

colony: forms a film

filamentous: forms a chain of cells

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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)

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5. Eukaryotes are bigger and more

“complicated”

• Eukaryotes • have membrane-bound organelles

• have chromosomes

• unicellular or multicellular

• include animal and plant cells

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Advantages of each kind of cell architecture

Prokaryotes Eukaryotes

simple and easy to grow

can specialize

fast reproduction multicellular

very similarcan build large bodies

WHAT IS THE DEAL

WITH CELL SIZE?

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Relative Size

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LAB ACTIVITYInvestigation of Surface Area

and Volume

The Discovery of the Cell

A historical look into the discovery of the cell

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1. Robert Hooke

• English scientist

• 'Micrographia’ (1665)

• studied bark/cork – dead cells, opaque

• studied small invertebrates

• proposed that plants and fungus had cells

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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

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Development of Cell Theory

Between the Hooke/Leuwenhoek discoveries and the mid-19th century, very little cell advancements were made for 150-200 years.

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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

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4. Rudolf Virchow • German physician

• research in cellular pathology

• In 1858 confirmed:• CELLS MUST

ARISE FROM PRE-EXISTING CELLS

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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

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Timeline for the Discovery of Cells

• 1590

• Hans and Zacharias Jansen constructed the first crude compound microscope.

• 1665

• 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.

• 1680

• 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”.

• 1839

• Theodor Schwann studied animal tissue under a microscope and found that animals were also composed of cells.

• 1855

• Rudolph Virchow stated that all living cells come from other living cells.21

Contributors (the “big picture”

slide)Robert Hooke

An English physicist who first saw cells in cork in 1665.

Anton Van LeeuwenhoekA Dutch businessman who perfected the microscope in 1674.

Theodor SchwannGerman zoologist who concluded that all animals are made of cells.

Rudolph VirchowGerman physicist/ pathologist who, in 1855, proposed that all cells come from existing cells.

Matthias SchleidenGerman botanist who determined, in 1838, that all plants are made of cells.

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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.

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