What is the difference between Rough Endoplasmic Reticulum and Smooth Endoplasmic Reticulum?

Question

What is the difference between Rough Endoplasmic Reticulum and Smooth Endoplasmic Reticulum?

Answer 1

The morphological differences between RER and SER allow these two regions of the ER to be distinguished visually; for example, the SER is often more convoluted than RER, and the RER tends to be more granular in texture. These differences in appearance may be directly related to the presence of bound ribosomes on the RER as there is some evidence that this affects ER structure . Ultimately, however, the distinction between the two must be explained by differences in membrane protein composition. Most membrane proteins are shared between RER and SER (general ER proteins), but several proteins involved in translocation or processing of newly synthesized proteins are enriched in RER, as shown by the fractionation of liver cells.

Since protein translocation is essential for all eukaryotic cells, they all have RER. One type of SER that is also found in all cells is the transitional ER. It is involved in packaging proteins for transport from the ER to the Golgi and is enriched in proteins required for this process. However, SER is abundant only in certain cell types, such as in steroid-synthesizing cells, liver cells, neurons and muscle cells. The primary activities of the SER are very different in each of these cell types . In liver, the SER is important for detoxification of hydrophobic substances. In steroid producing cells, it is the site of many of the synthesis steps. In muscle, it is called sarcoplasmic reticulum (SR) and is primarily involved in calcium release and uptake for muscle contraction and in neurons, although less well established, it is also probably required for calcium handling. Thus, the SER acts as an overflow site to house upregulated enzymes, and as these enzymes vary, it is also a cell type-specific suborganelle. Why are bound ribosomes concentrated in the RER and excluded from SER, rather than being found at lower levels throughout the ER? One proposed explanation is that the functions associated with bound ribosomes (translocation and modification of newly synthesized proteins) are more efficient if the proteins performing them are concentrated in one part of the membrane.

It is not known how the RER and SER maintain distinct protein compositions. Perhaps, like inner NE proteins, RER membrane proteins are localized by tight binding to a fixed substrate. In this case, the best candidate substrate would be ribosomes as they are essentially fixed and, at least in one system, co-localize with RER membrane proteins. The parallel between RER and NE protein targeting is not, however, complete, as FRAP experiments show that localized RER membrane proteins are not immobilized like NE membrane proteins. Other mechanisms, for example, active retrieval from the SER, may play a role in the concentration of RER membrane proteins.

Answer 2

rough endoplasmic reticulum[RER] has ribosomes attached to it giving a rough appearance thereby deriving its name.                        

smooth endoplasmic reticulum[SER] is devoid of ribosomes.

RER- involved in protein synthesis as ribosomes are concerned with protein  synthesis.

SER-concerned with lipid synthesis in intestinal cells&

        with steroid formation in adrenals

        

Answer 3

SER does not contain ribosomes. RER contains ribosomes.

Answer 4

Endoplasmic reticulum Studdede with ribosomes are called Rough Endoplasmic Reticulum

And ER having Smooth surface is called Smooth Endosplasmic Reticulum.

Answer 5

rough ones have ribosomes attached 2 dem

Answer 6

There are a lot of ribosomes covering the surface of rough ER, giving it a "rough" appearance.

There are several other differences, too.

Answer 7

80 s ribosomes are attached with RER( rough endoplasmic reticulum) wheras ribsomes are not attached with  SER ( smooth endoplasmic reticulum ) .

rer helps in protein synthesis and ser helps in lipid and steriod synthesis and stores calcium

rer is mainly found near the nucleus and golgi bodies  whereas ser is is found in the whole cell

rer has rough surface due to attached ribosomes but ser has smooth surface  

Answer 8

rough ER has ribosomes on it, giving it a 'rough' appearance .it transports proteins synthesized by the ribosomes to various parts of the cell, and outside too. smooth ER has no ribosomes, and usually connects the nuclear membrane to the cell membrane

Answer 9

in rough ER the ribosomes are attached to the membrane in smooth ER it is absent

Answer 10

The endoplasmic reticulum, or ER, is an organelle found in all eukaryotic cells that is an interconnected network of tubules, vesicles and cisternae.These structures are responsible for several specialized functions: protein translation, folding and transport of proteins to be used in the cell membrane (e.g. transmembrane receptors and other integral membrane proteins), or to be secreted (exocytosed) from the cell (e.g. digestive enzymes); sequestration of calcium; and production and storage of glycogen, steroids, and other macromolecules.[2] The endoplasmic reticulum is part of the endomembrane system. The basic structure and composition of the ER membrane is similar to the plasma membrane.

[edit] Rough endoplasmic reticulum

The surface of the rough endoplasmic reticulum is studded with protein-manufacturing ribosomes giving it a "rough" appearance (hence its name).[3] But it should be noted that these ribosomes are not resident of the endoplasmic reticulum initially. The ribosomes only bind to the ER once it begins to synthesize a protein destined for sorting.[4] The free ribosome begins producing the polypeptide until a cytosolic signal recognition particle recognizes the pre-piece of 5-15 hydrophobic AAs preceded by a positively charged (basic) amino acid. This makes it easy for the complex to loop the sequence through the hydrophobic membrane. The pre-piece is then cleaved off.

The membrane of the rough endoplasmic reticulum is continuous with the outer layer of the nuclear envelope. Although there is no continuous membrane between the rough ER and the Golgi apparatus, membrane bound vesicles shuttle proteins between these two compartments.[5] COP II brings vesicles to the golgi and COP I brings the membrane back. The rough endoplasmic reticulum works in concert with the Golgi complex to target new proteins to their proper destinations.

The RER is key in producing

lysosomal enzymes with a Mannose-6-phosphate marker added in the cis-Golgi network

Secreted proteins, either secreted constitutively with no tag, or regulated secretion involving clathrin and paired basic amino acids in the signal peptide.

integral membrane proteins that stay imbedded in the membrane as vesicles exit and bind to new membranes. Rab proteins are key in targeting the membrane, SNAP and SNARE proteins are key in the fusion event.

initial glycosylation as assembly continues. This is either N-linked or O-linked (O-linked may likely occur in the golgi).

N-linked glycosylation: if the protein is properly folded, glycosyltransferase recognizes the AA sequence NXS or NXT (with the S/T residue phosphorylated) and adds a 14 sugar backbone (2 N-acetylglucosamine, 9 branching mannose, and 3 glucose at the end) to the side chain nitrogen of Asn.

[edit] Smooth endoplasmic reticulum

The smooth endoplasmic reticulum has functions in several metabolic processes, including synthesis of lipids and steroids, metabolism of carbohydrates and calcium concentration, drug detoxification, attachment of receptors on cell membrane proteins, and steroid metabolism.[6] It is connected to the nuclear envelope. Smooth endoplasmic reticulum is found in a variety of cell types (both animal and plant) and it serves different functions in each. The Smooth ER also contains the enzyme Glucose-6-phosphatase which converts glucose-6-phosphate to glucose, a step in gluconeogenesis. The Smooth ER consists of tubules and vesicles that branch forming a network. In some cells there are dilated areas like the sacs of rough endoplasmic reticulum. The network of smooth endoplasmic reticulum allows increased surface area for the action or storage of key enzymes and the products of these enzymes. The smooth endoplasmic reticulum is known for its storage of calcium ions in muscle cells.

Answer 11

c**p thats a fairly simple question, but i can't for the life of me remember

I took this stuff 10 years ago, hard to remember.

I'd like to know too :P

Answer 12

Presence of ribosome on the surface of RER while SER does not have any ribosomes

Answer 13

Rough Endoplasmic Reticulum has 'Ribosomes' on it...thus giving a rough look...

Ribosomes are the structures which facilitate in protein synthesis...

Whereas smooth endoplamic reticulum doesn't possesses the ribosomes...

Answer 14

There are a lot of ribosomes covering the surface of rough ER, giving it a "rough" appearance.

There are several other differences, too.

rough does not attached to the nucleus and smooth does

Answer 15

Endoplasmic reticulum Studdede with ribosomes are called rough endoplasmic Reticulum where as without ribosomes are called smooth endoplasmic reticulam.