The Cell History, Microscopes & Cell Theory

Cell Organism’s basic unit of structure and function Lowest level capable of activities of life Cells are: *Single-celled organisms *Subunits of many-celled organisms

What led to cell discovery? The invention of the MICROSCOPE!!!! Invention of the microscope made the study of Biology possible. Increased the life expectancy of people

Domain of Prokaryotes - Bacteria

Staph Bacteria

Bacteria that live in our Gut - If they died, we would starve in a month

Pseudomonas Bacteria – Issue: Burn Victims and Cystic Fibrosis

Streptococcus – Strep Throat

Anton van Leeuwenhoek The first living cells were seen by Anton van Leeuwenhoek. Anton van Leeuwenhoek was a Dutch cloth merchant who is given credit for making the first microscope. The first microscope he made was to inspect the quality of cloth. 1665

Robert Hooke The structure of the cell was first described by Robert Hooke (1700), an Irishman. Hooke thought that the squares of the cork that he viewed through the microscope looked like the rooms, or “cells”, that the monks lived in at the monasteries.

Hooke’s 1 st Microscope

Robert Hooke’s Cork Cells Drawing

Compound Light Microscope  view living organisms  Limited magnification  loss of resolution  Use a light source or mirrors to focus light on subject

Limiting Factor of Light Microscopes Resolution is limited due to the properties of visible light Ability to distinguish one thing from another Small bacteria are the smallest things you can “make out” with light microscopes Desire to see smaller things drove invention of electron microscopes

Compound Light Microscope OcularObjectiveTotal Magnification 10X4X40X 10X10X100X 10X40X400X

Light Microscope – Red Blood Cells

Normal and Sickle Red Blood Cell (SEM)

Electron Microscopes- (Expensive) Hospitals & Universities

Electron Microscopes Gave ability to observe more cellular detail Smaller things 3 Types of Electron Microscope ▫TEM (Transmission Electron) ▫SEM (Scanning Electron) ▫SPM (Scanning Probe) TEM image

Transmission Electron Microscopes TEM aims a beam of electrons through a specimen Denser areas appear darker Two dimensional images No live specimens with TEM or SEM

TEM Image of Elodea Cell

Scanning Electron Microscope (SEM) – 3D image Must slice objects very thin Sections laid out and stained with gold Creates magnified images by using electrons instead of light waves. A beam of high energy electrons is shot onto the specimen. Beam travels through a series of magnetic lenses designed to focus the electrons to a very fine spot.

SEM Procedures

(SEM) Shows very fine details of specimens – but surface only

SEM Image of Red Blood Cells Forming a Clot

Scanning Probe Microscope Three dimensional computer image of the surface of a specimen. Can view a specimen as small as one atom!!!

Cell Theory Schleiden and Schwann – All living things are made of cells 2. All cells come from pre-existing cells (life came from life) 3. The cell is the basic unit of structure and function of all organisms

Schwann studied Animals: Concluded that animal tissues are composed of cells.

Schleiden studied Plants: Carefully studied plant tissues and concluded that all plants are composed of cells.

Rudolf Virchow Rudolf Virchow studied disease and came up with … All cells come from pre-existing cells (life came from life)

Schleidan + Schwann + Virchow = CELL THEORY

Profound Discovery People had believed that mice and maggots spontaneously generated from piles of grain and rags Discovered by putting cheesecloth over rotting meat to prove flies causes maggots

Unicellular organism ▫Composed of one cell and all of life’s activities occur within that cell. Multicellular organism ▫Each cell carries on most of the major functions of life

We’re able to identify tiny details with modern microscopes

Plants Example: Elodea – water weed

Elodea cells (Plant cells)

Plant Cell Structure

Animal cell – Liver cell