An excited fluorescent molecule such as GFP or YFP can dispose of the energy from the absorbed photon in either of two ways: 

by fluorescence, emitting a photon of slightly longer wavelength (lower energy) than the exciting light, or 

by nonradiative fluorescence resonance energy transfer (FRET).

TLS Online TPP Program

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The length of Introns is variable while exons are almost constant in length.

TLS Online TPP Program

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#Unit 2. Cellular Organization

Genes that share a common ancestry have similar organizations with conservation of the positions (of at least some) of the introns.

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#Unit 2. Cellular Organization

The homology between two genes can be plotted in the form of a dot matrix comparison

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#Unit 2. Cellular Organization

Sequences that presumably diverged as a result of gene duplication are paralogous.

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#Unit 2. Cellular Organization

A gene family is defined as a group of genes that encode related or identical products as a result of gene-duplication events.

TLS Online TPP Program

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#Unit 2. Cellular Organization

Sequences that arose because of speciation are described as orthologous