Specialization of cells and organelles

AI Thread Summary
In multicellular organisms, undifferentiated cells beyond stem cells do exist, such as progenitor cells, which play crucial roles in tissue regeneration and repair. These cells can differentiate into various cell types, contributing to the organism's development and maintenance. Regarding the endoplasmic reticulum (ER), the structural differences between smooth ER and rough ER account for their distinct functions. Rough ER is studded with ribosomes on its cytoplasmic surface, which are responsible for synthesizing proteins. In contrast, smooth ER lacks ribosomes and is primarily involved in lipid synthesis and detoxification processes. The absence of ribosomes on smooth ER is due to its specific role in lipid metabolism rather than protein production, which is the primary function of rough ER.
MathewsMD
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Hi,

I just had 2 questions.

1. In multicellular organisms, are there any undifferentiated cells besides stem cells? Do they play any significant role?

2. Why is it that smooth ER does not have ribosomes attach to it but rough ER can have ribosomes come and attach? Is there a structural difference b/w the two types of ER? All I've been getting is that rough ER has ribosomes (which attach from cytosol) but why can't this happen on smooth ER? Likewise, why does the rough ER not create lipids like the smooth ER?

Any help would be much appreciated!
 
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