Sexual dimorphism can evolve when selection favors the expression of a trait to be different in males and females. 

This situation is called sexually antagonistic selection, because an increase in the trait’s expression benefits one sex but harms the other.

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#Unit 13. Methods in Biology

There are two major advantages to running gradient gels. 

First, a much greater range of protein Mr values can be separated than on a fixed- percentage gel.

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#Unit 13. Methods in Biology

The second advantage of gradient gels is that proteins with very similar M r values may be resolved.

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#Unit 13. Methods in Biology

The higher no. of band will be observed in gradient gel electrophoresis comparison to uniform gel SDS and Native gel electrophoresis.

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#Unit 13. Methods in Biology

Isoelectric Focusing Gels is based on the separation of molecules according to their different isoelectric points at which the show zero electrophoretic mobility.

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#Unit 13. Methods in Biology

In the Isoelectric Focusing pH gradient is formed by the introduction into the gel of compounds known as ampholytes, which are complex mixtures of synthetic polyamino-polycarboxylic acids Ampholytes can be purchased in different pH ranges covering a wide band (e.g. pH 3–10).

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#Unit 13. Methods in Biology

IEF is a highly sensitive analytical technique and is particularly useful for studying  microheterogeneity in a protein. For example, a protein may show a single band on an SDS gel but may show three bands on an IEF gel. This may occur, for example, when a protein exists in mono-, di- and tri-phosphorylated forms.