Endoplasmic Reticulum (ER). This folded membrane forms sacs to store proteins or other substances. It creates a vast surface area where the manufacture of proteins and new membranes can take place. <span>Endoplasmic reticulum is a folded mass of membranes made of the same phospholipids found in the plasma membrane. There are two types of ER smooth (without ribosomes) and rough (with ribosomes)<span>
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Cross over is the first way genes are shuffled to give rise to genetic diversity. Cross over takes place in sexual reproduction. The normal way that cross over occurs is chromosomes line up side by side and break off pieces of themselves, then trade those pieces with each other.
If they break the pieces at the same locus in the sequence of base pairs, the result is an exchange of genes called genetic recombination and it ensures that the daughter cells produced have a different genetic makeup from the parent cell and thus diversity occurs.