16. There are many diseases that are affected by the dysfunction of the rough en

Question

16. There are many diseases that are affected by the dysfunction of the rough endoplasmic reticulum (ER), including Alzheimer's. A dysfunctional ER could result in A. Proteins not translated correctly by free ribosomes. B. Incorrect folding of proteins. C. The lack of a signal sequence on the mRNA of these proteins. D. mRNA of the proteins is not transported from the nucleus to the cytoplasm. E. More than one answer above is plausible. 17. Liver cells, which aid in detoxification, will havewhile skeletal muscle cells wil most likely have A. high amounts of mitochondria; low amounts of mitochondria. B. high amounts of smooth ER; low amounts of smooth ER. C. high amounts of smooth ER; high amounts of mitochondria. D. low amounts of smooth ER; high amounts of mitochondria. E. low amounts of smooth ER; low amounts of mitochondria.

Explanation / Answer

Ans) B. Incorrect folding of proteins

The endoplasmic reticulum is a part of endomembrane system involved in the protein synthesis, modification of proteins, sorting of proteins and detoxification. Morphologically it is composed of the cisternae, tubules, and vesicles. Based on surface morphology it is divided into the smooth endoplasmic reticulum (devoid of ribosomes) and rough endoplasmic reticulum (coated with ribosomes). Glucose 6 phosphatase is the marker enzyme of the endoplasmic reticulum.

Endoplasmic reticulum (ER) dysfunction can lead to the development of neurological disorders like Alzheimer's disease, cerebral ischemia, and prion diseases. Protein misfolding in the endoplasmic reticulum produces an unfolded protein which is targeted to the neurons. The unfolded protein in neuron does not perform its functions properly which leads to the development of neurological disorders like Alzheimer's disease.

Ans) C. High amounts of ER; High amounts mitochondria

In liver smooth endoplasmic reticulum involved in the detoxification of xenobiotics. An important component of detoxification mechanism is a cytochrome anchored to the endoplasmic reticulum membrane called Cytochrome P450 which catalyzes the hydroxylation reactions. It increases the solubility of xenobiotics by addition of hydroxyl groups so that they are easily eliminated by the kidney.

Mitochondria: it is also called powerhouse of the cell and it is a double membrane-bound organelle found in all eukaryotes. It produces huge quantities of energy in the form of adenosine triphosphate (ATP). In muscle cells, there is high demand for energy so muscle tissue will have the high number of mitochondria.

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