Technique in cellular and molecular biology

What is resolution?

• Deals with factors that allow an object to be observed

• Requires the specimen and the background have different refractive indexes

• The ability to distinguish two points

• Being able to see the specimen better

What is visibility?

• The ability to distinguish of two points

• Deals with factors that allow an object to be observed

• The ability to distinguish two points

• Direct light towards the specimen

What is contrast?

• Collects light from the specimen

• Forms an enlarged, visual image

• Refers to the darkness of the background relative to the specimen

• Deals with factors that allow an object to be observed

What is the limit of resolution?

• A light that illuminates the specimen is seen as a bright background

• An intact object, either living of dead

• Refers to its ability to distinguish between two closely spaced Airy disks in the diffraction pattern

• Provides the observer with increased magnification and resolution

What are light microscopes used to observe?

• To distinguish between two closely spaced Airy disks

• Used to study living cells and for regular use when relatively low magnification and resolution is enough.

• Provide higher magnifications and higher resolution images but cannot be used to view living cells.

• Visualizes transparent objects by converting differences in refractive index of some parts of the specimen into light intensity differences

What is fluorescence microscopy?

• Allows visualization of living cells

• uses fluorescence instead of scattering, reflection, and attenuation or absorption, to study the properties of specimen

• Images formed from electrons reflected from specimen surface

• When cells are grown on the flat surface of a dish.

What compound are used in fluorescence microscopy?

• Electrons

• Protons

• Fluorescence

• Light

What are the different types of electron microscopy?

• Transmission Electron Microscopy (TEM)

• Scanning Electron Microscopy (SEM)

• Photographic Electron Microscopy (PEM)

• Fluorescence Electron Microscopy (FEM)

What is Scanning Electron Microscopy (SEM)?

• Uses fluorescence's to view specimens

• Uses electrons instead of light to form images

• Images that form from electrons reflected from specimen surface, which are covered in metal

• Heavy metal diffuses into spaces between specimen molecules.

What is Transmission Electron Microscopy?

• Uses electrons instead of light to form images

• Heavy metal diffuses into spaces between specimen molecules.

• Images formed from electrons reflected from specimen surface, which are often covered in metal

• Uses protons to view specimens