Picture attached, can someone briefly explain?

role of endoplasmic reticulum in protein modification and packaging:

Newly synthesized polypeptides in the membrane and lumen of the ER undergo five principal modifications before they reach their final destinations:

The first two and the last of these modifications, which take place exclusively in the rough ER, are discussed in this section. Although addition of some carbohydrates and some proteolytic cleavages also occur in this organelle, many such modifications take place in the Golgi complex or forming secretory vesicles; we discuss these in later sections.

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the cladogram shown here shows similarities and differences among several classes of vertebrates. anatomically, the four have limb structure as their common ancestor. we might separate the mammals from the other three classes because they a) divergent; do not lay eggs b) identical; are warm-blooded c) varied; a four chambered heart d) homologous; have mammary glands