Q. What is the size of rough endoplasmic reticulum in micrometers?
Reticulum (in most plant cells) 0.5 µm thick (each layer) 7.
Q. What is the endoplasmic reticulum made of?
Rough endoplasmic reticulum is an organelle found in eukaryotic cells. Its main function is to produce proteins. It is made up of cisternae, tubules and vesicles. The cisternae are made up of flattened membrane disks, which are involved in the modification of proteins.
Q. How is the endoplasmic reticulum created?
We have established an in vitro system for the formation of the endoplasmic reticulum (ER). Starting from small membrane vesicles prepared from Xenopus laevis eggs, an elaborate network of membrane tubules is formed in the presence of cytosol. In the absence of cytosol, the vesicles only fuse to form large spheres.
Q. What are three main functions of endoplasmic reticulum?
The endoplasmic reticulum (ER) serves important functions particularly in the synthesis, folding, modification, and transport of proteins.
Q. What is the difference between sarcoplasmic reticulum and endoplasmic reticulum?
The sarcoplasmic reticulum (SR), from the Greek σάρξ sarx (“flesh”), is smooth ER found in muscle cells. The only structural difference between this organelle and the smooth endoplasmic reticulum is the medley of proteins they have, both bound to their membranes and drifting within the confines of their lumens.
Q. Do muscle cells have ER?
Skeletal muscle has a specialized form of ER known as sarcoplasmic reticulum (SR). The SR is a storage depot for calcium and regulates its release during myofibrillar contraction; hence, the SR has a critical role in muscle contraction and the maintenance of muscle homeostasis.
Q. What ion is needed for muscle contraction?
The muscle contraction cycle is triggered by calcium ions binding to the protein complex troponin, exposing the active-binding sites on the actin.
Q. What is the difference between bound and free ribosomes?
Free ribosomes are present in the cytosol, the watery fluid inside the cell and are not attached to any other structure. Whereas membrane-bound ribosomes produce proteins that are exported from the cell to be used elsewhere, free ribosomes produce proteins used inside the cell itself.
Q. What proteins are made on free ribosomes?
In contrast, proteins destined to remain in the cytosol or to be incorporated into the nucleus, mitochondria, chloroplasts, or peroxisomes are synthesized on free ribosomes and released into the cytosol when their translation is complete.
