Cell/Molec: L1 CH 1 Cells and How Cells Are Studied

Bright Field Microscopy

• Allows for quick, inexpensive views of tissue and cellular morphology

• Transparent objects (whole mounts, sections, cultured cells) often must be made visible by staining (toxic)

• Limited resolution (at best, small organelles such as mitochondria might be visible)

Phase Contrast Microscopy

• Highly transparent objects made more visible without staining

• Differences in refractive index of various parts of the specimen converted into differences in light intensity

• Easy views of living cells (with glowing ring artifact)

• Moderate cost

Differential interference contrast (DIC)

• Highly transparent objects made more visible without staining

• Images lack the “glowing ring” artifact of Phase Contrast

• Increases resolution of images

• Typically reserved for projects that require high-quality 3D views of structures

Fluorescence Microscopy

• A type of light (contrast) microscopy

• The cell or subcellular structures (organelles, proteins, etc.) are made to fluoresce to generate an image

• Dyes or tags with different fluorescence emission wavelengths (represented as different colors) can be used to distinguish different cells and cellular components, OR to track metabolic activities, protein expression, other macromolecules, and more

Electron Microscopy

• Electron beam rather than light beam

• Much greater resolution but much greater time and expense

• Not for routine use

• Subcellular structures can be visualized

• Detailed view of cell surface

The Cell Theory

1. All organisms are composed of one or more cells

2. The cell is the structural unit of life

3. Cells arise only by division from a pre-existing cell

Select the best type of microscopy for the following experimental goals:

• The best possible resolution is needed to view subcellular structures of a cell

Select the best type of microscopy for the following experimental goals:

• Need to observe specimens of high contrast

Select the best type of microscopy for the following experimental goals:

• Need the organism alive to observe its growth

Select the best type of microscopy for the following experimental goals:

• Want to observe the cells using flurochrome-conjugated antibodies to highlight specific celular structures

Select the best type of microscopy for the following experimental goals: