223.01 introduction to cells
DESCRIPTION
intor to cellsTRANSCRIPT
BIOL223
223.1Introduction to Cells
THEORY OF SPONTANEOUS GENERATION
Aristotle (~340 B.C)some creatures (plants, animals)
come from parents of their own kind
others (insects, vermin) are generated spontaneously in putrefying (rotting) matter from air and “vital heat”
idea held true for 2 millenia
THEORY OF SPONTANEOUS GENERATION
17th century recipe for mice:sweaty underwearhandful of grainopen-mouth jarincubate for 21 days
DISCOVERY OF CELLS
Robert Hooke (1665)developed compound light
microscopedetailed studies of “cork”
DISCOVERY OF CELLS
“. . . I could exceedingly plainly perceive it to be all perforated and porous, much like a Honey-comb, but that the pores of it were not regular. . . . these pores, or cells, . . . were indeed the first microscopical pores I ever saw, and perhaps, that were ever seen, for I had not met with any Writer or Person, that had made any mention of them before this. . .”
INTERPRETATION OF GERM CELLS
Nicolaas Hartsoeker (1695)discovered “animalcules” in the
semen of humans and animalsbelieved in the theory of
Preformationism: the sperm was or contained a
“little man” with little genitals and even smaller sperm, ad infinitum
it was thus that “in Adam” (literally), all had sinned
FORMULATION OF CELL THEORY
Matthias Schleiden (1804–81)Botanist1838 detailed studies of plant cells
Theodor Schwann (1810–82)Zoologist1839 detailed studies of animal cells
FORMULATION OF CELL THEORY
Schleiden and Schwann are credited with developing
Cell Theory
THEORY vs LAW
a testable* concept used to explain observations (*disprovable)
Theory of Gravity: theory of relativity: a
consequence of the curvature of space-time
quantum field theory: gravity modulated by particles in a field
generalizations of observations, used to make predictions a
Law of Gravity: Force of gravity is
proportional by inverse square to mass of two objects separated in space
THEORY vs LAW
a testable* concept used to explain observations (*disprovable)
Theory of Eclipse sun-eating dragon
generalizations of observations, used to make predictions a
Law of Eclipse: accurate prediction
CELL THEORY1.
All living things are made up of cells and cell products.cells are the fundamental
units of structure and function in the living tissue of all of God’s creatures
cells can live separate from the rest of the organism
“Every animal appears as the sum of vital units, each of which bears in itself the complete characteristics of life.” Rudolf Virchow
CELL THEORY
Fungi
EUKARYA
Trypanosomes
Green algae
Land plants
Red algae
ForamsCiliates
Dinoflagellates Diatoms
Animals
AmoebasSlime molds
Leishmania
Euglena
Green nonsulfur bacteriaThermophiles
Halophiles
Methanobacteria
Sulfolobus
ARCHAEA
COMMONANCESTOR
BACTERIA
(Plastids, includingchloroplasts)
Greensulfur bacteria
(Mitochondrion)
Cyanobacteria
ChlamydiaSpirochetes
CELL THEORY
2.
All cells arise from pre-existing cells (Virchow, 1858)cells are autonomous and can
self-replicatecells arise from the division of
pre-existing cells“Where a cell arises, there must be a previous cell...” Rudolf Virchow
INTRODUCTION TO CELLULAR FEATURES
• Typically 5-20mm (diameter)• Limit of light microscope resolution
• 0.4-0.7mm • Can see larger organelles
• Nucleus, Mitochondria
INTRODUCTION TO CELLULAR FEATURES
a
Light Microscope Electron Microscope
Amphiuma kidney, Janus Green stain Goldfish intestine, TEM preparation
400X 50,000X
INTRODUCTION TO CELLULAR FEATURES
EukaryoticGreek…“Eu”=True or Good…“Karnon”=NutTrue/Nut - True Nucleus, Has a nucleusPlant and animal cells (multicellular)Yeast and protozoa (unicellular)
INTRODUCTION TO CELLULAR FEATURES
Prokaryotic “Pro”=Prefix, Before…“Karyon”=kernel or NucleusBefore/Nucleus - No NucleusAlludes to the idea that they are ancestors to
EukaryotesUnicellularDivision within the prokaryotes
Eubacteria Archaebacteria (1977)
Hostile environments Vastly different (Genetically)
The key to every biological problem must finally be sought in the cell, for every organism is, or at sometime has been, a cell.
- E.B. Wilson (1925)
Single Cells to Multicellular Organisms
Cell differentiationCohesion (plants vs. animals)Cell communicationDifferential gene expression