Pancreatic beta cells secrete the hormone insulin to regulate blood glucose leve
ID: 144351 • Letter: P
Question
Pancreatic beta cells secrete the hormone insulin to regulate blood glucose levels. Which of the following organelles are beta cells most likely to have in abundance and why?
Mitochondria – because insulin is also used to synthesize ATP
Peroxisomes – because excess insulin must be recycled to avoid toxic levels
Smooth ER – because insulin is a steroid hormone like testosterone
Centrosomes – because extra microtubules are needed for insulin transport
Plasmodesmata – because insulin is secreted through plasmodesmata in the cell membrane.
Rough ER – because insulin is a secreted protein synthesized by bound ribosomes
a.Mitochondria – because insulin is also used to synthesize ATP
b.Peroxisomes – because excess insulin must be recycled to avoid toxic levels
c.Smooth ER – because insulin is a steroid hormone like testosterone
d.Centrosomes – because extra microtubules are needed for insulin transport
e.Plasmodesmata – because insulin is secreted through plasmodesmata in the cell membrane.
f.Rough ER – because insulin is a secreted protein synthesized by bound ribosomes
Explanation / Answer
A).
Mitochondria :
Mitochondria have a significant role in the proper and efficient functioning of beta cells: In response to rise in blood glucose levels, mitochondria generate metabolic signals which induce insulin secretion. The mitochondrial oxidative metabolism generates about 98% of the ATP of the beta cell.
Endoplasmic Reticulum
Pancreatic beta cells have well-developed endoplasmic reticulum (ER) to accommodate for the massive production and secretion of insulin. ER homeostasis is vital for normal beta cell function. Perturbation of ER homeostasis contributes to beta cell dysfunction in both type 1 and type 2 diabetes. To systematically identify the molecular machinery responsible for proinsulin biogenesis and maintenance of beta cell ER homeostasis, a widely used mouse pancreatic beta cell line, MIN6 cell was used to purify rough ER.
In pancreatic beta cells, the well-developed ER is responsible for the synthesis, folding and export of proinsulin.Therefore, ER homeostasis, the balance between the client protein load and processing capacity of the ER, is vital for normal beta cell function.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.