1. A Tour of the Cell

2. Importance of cells
A cell is the simplest collection of matter that can live.
Everything an organism does occurs as a result of what takes place at the cellular level.
All cells are descended from earlier cells.
Biblical standpoint: from cells and organisms made during Creation Week (Genesis 1,2)
Secular standpoint: from one original cell 3.5 billion years ago that has been modified in many ways over evolutionary history (p.19)

3. Three Domains of Life Bacteria Archaea Eukarya Prokaryotes
Most are unicellular and microscopic
Most diverse prokaryotes
Archaea
Live in extreme environments
Eukarya
Includes 3 kingdoms: Plantae, Fungi, and Animalia (distinguished by modes of nutrition)

4. Same: bound by plasma membrane, cytoplasm filled with cytosol, chromosomes (contain genes/dna), and ribosomes
Prokaryotes
Eukaryotes
DNA is concentrated in a region called the nucleoid without a membrane
NO membrane-bound organelles
Smaller
DNA is located in a membrane-enclosed nucleus
Membrane-bound organnelles
Larger

5. Microscopy: Magnification (ratio of image size to real size) & Resolution (clarity of image)
Light Microscopes
Invented in 1590 and used by Renaissance scientists
Improved versions are used today to observe live specimens
Visible light passes through the specimen, then through glass lens
Projected into eye, film, digital sensor, or video screen
Cannot resolve detail smaller than a bacterium
Up to 1,000X magnification
Sometimes specimens are stained for contrast

6. Microscopy: Magnification (ratio of image size to real size) & Resolution (clarity of image)
Electron Microscopes
Invented in 1950s
Uses a beam of focused electrons
Resolution is much better than light microscope
Non-living specimens
2 kinds:
Scanning Electron Microscope (SEM)
Scans the surface of a sample & gives 3D image
Transmission Electron Microscope (TEM)
Specimens are stained with atoms of heavy metals that attach to cellular structures
Electron beam is aimed through the sample
Profiles a thin section of the interior