The Endoplasmic Reticulum

The endoplasmic reticulum is specialised for protein processing and lipid biosynthesis. One of its primary functions is to regulate the ionic concentration in the cytoplasm via the movement of Ca2+, via ionic pumps and channels. It also contains enzymes responsible for the metabolising of drugs. Endoplasmic reticulum (ER) can come in two forms. As depicted in Fig. 2 Rough ER has ribosomes present as part of the membrane of the organelle, and together with these ribosomes takes polypeptides and amino acids from the cytosol and synthesises proteins destined for attachment to cell membranes. It is in the lumen of the rough ER that the proteins are folded into the specific three dimensional shapes that are so important for biochemical recognition and linking sites [6]. It is called rough because of the presence of ribosomes makes the surface of the membrane look rough, unlike smooth ER, which lacks the ribosomes so the membrane looks smooth. Rough ER is composed of a large but convoluted flattened sac. The main function of the smooth ER is the production of lipids and the metabolism of compounds (such as the breakdown of glycogen into glucose). Because of the different functions between the rough and smooth ER, different specialised cells will have different amounts of each; for example, hepatic

1. An understanding of chemistry is important for an understanding of biology because biology needs the models of chemistry to better describe life.

-Sarcoplasmic Reticulum (SR) then releases Calcium which binds to troponin in the thin filament, exposing myosin-binding sites;

My sisters and I love to go shopping, we then have lunch together when we’re done

You may use the lab manual, pre-lab lectures, and credible internet resources, however you may not use your cell bio lab classmates as a resource. You will most likely see this material again on the Final and I highly encourage you to work individually and seek help from myself or your TA. Plagiarism will result in an automatic zero.

There are two types of Endoplasmic Reticulum the Smooth ER and the Rough ER. you can distinguish that both of the ER’s are different to each other, this is shown in the diagram above that one is smooth ER and the other is rough ER the rough ER has ribsomes attracted to it while the smooth ER does not have ribosomes attached to it. The two ER’s have different function to each other.

An individual that plays only part of its role because of competition or other types of species interactions is said to display a realized niche. Species over time divide the resources they commonly use by specializing in different ways.

The body has two faces, the cis face which fuses with incoming transport vesicles, and the trans face which excretes the secretory vesicles. The cis face fuses with vesicles coming from the ER effectively from many directions due to its convex shape, whereas the concave trans face can direct the secretory vesicles to their destination. When fusing with the cis face, the transport vesicles release their proteins to be absorbed for modification. Each cisternal layer of the Golgi body holds different enzymes which each modify the passing proteins in separate ways. Between the layers the proteins are moved through the gaps by small vesicles. When a protein has been modified correctly, it leaves the Golgi body via secretory vesicles which then carry the modified proteins to the cell membrane or another organelle. The proteins that are transported to the cell membrane are either excreted from the cell, or absorbed into the membrane to aid with its function. Some of the secretory vesicles which hold hydrolytic enzymes stay within the cytoplasm and function as lysosomes.

7-8 Study Hall Daywitt, Jean A126 08:15 AM - 08:59 AM 7-8 Study Hall Daywitt, Jean A126 08:15 AM - 08:59 AM 7-8 Study Hall Daywitt, Jean A126 08:15 AM - 08:59 AM 7-8 Study Hall Daywitt, Jean A126 08:15 AM - 08:59 AM 09:00 AM 7 MUSIC Matchey, Gideon C126 09:02 AM - 09:46 AM 7 MUSIC Matchey, Gideon C126 09:02 AM - 09:46 AM 7 MUSIC Matchey, Gideon C126 09:02 AM - 09:46 AM 7 MUSIC Matchey, Gideon C126 09:02 AM - 09:46 AM 7 Reading Knobloch, Brenda A116 09:49 AM - 10:33 AM 7 Reading Knobloch, Brenda

sHSPs are a ubiquitous class of chaperones found across all kingdoms of life. sHSP range in size from 12-42 kilo Daltons in large oligomers of 12 to >32 subunits and the structure is homologous across all species. The sHSP monomer consists of three domains: a disordered N-terminal arm, a beta-sandwich α-crystallin domain, and a flexible C-terminal extension. The N-terminal domain is the most variable region with little conservation between species. Experimental evidence also suggests N-terminal involvement in substrate binding and protection. The α-crystallin domain is the most highly conserved region and adopts a β-sandwich conformation composed of 7 to 8 anti-parallel β-strands (Basha et al, 2012). The C-terminus contains an I-X-I motif, which helps to satblizie the oligomeric form of the sHSP (Basha et al, 2012).

The rough endoplasmic reticulum is an organelle that plays a large role in synthesising and proteins. This is an important process called protein synthesis. (Plant Cell Anatomy, n.d.)

The chaperones have the main role of ensuring proper folding. When a chaperone protein becomes toxic, major changes in the conformation occur as the alpha helix becomes beta pleated sheets. The sheets now expose the hydrophobic amino acid and aggregation, or clumping together of sheets occurs (Borges, 2014).

Smooth Endoplasmic Reticulum (Smooth ER) – The smooth endoplasmic reticulum is very similar in terms of structure and chemically to the rough endoplasmic reticulum with the exception of not being able to attach ribosomes like the rough ER can. The smooth ER has more than just one main function and in simple terms these are control of calcium release within the muscle cells, breakdown of lipid soluble toxins in the liver and lipid steroid hormone synthesis. It primarily makes and process fat within a typical animal cell. The structure of the smooth ER is usually said to be tubular rather than sheet like and it may be separate from the rough ER or in some cases may in fact be an extension of it. The smooth ER is said to be most common in cells that metabolise fat and it is a continuation of the outer nuclear membrane of a cell. It is made up of a vast network of membrane which is usually covered in tubules and vesicles. Depending on the type of cells, the amount of rough and smooth endoplasmic reticulum that is present within it varies somewhat greatly. Endoplasmic means inside of the cytoplasm and the term reticulum means network. Rough Endoplasmic Reticulum (Rough ER) – The surface of the rough endoplasmic reticulum is covered in ribosomes which are

To start off endergonic reactions is basically a reaction in order for energy to be driven. Unlike its counterpart exergonic reactions, they are not spontaneous. When the event exergonic reaction occurs, it releases energy outside of the system and the released energy is then used to energize the endergonic reaction. In the case of how cells preform endergonic reactions would be that with exergonic reactions which results in ATP breaking down into ADP and into an inorganic group. The reaction releases energy in the form of ATP that is used to energize the endergonic reaction.

Molecular chaperones stabilize unfolded or misfolded proteins until native conformations have been obtained to promote cell survival during and after stress conditions. They do not change or add to the folding principles encoded by a protein because polypeptide chains inherently carry within them all the information that is necessary for achieving the native state of a protein. Instead, they optimize the folding process by stabilizing folding intermediates and are involved in every aspect of proteome maintenance including de novo folding, refolding of stress-induced misfolded proteins, and targeting proteins for degradation (Hartl 2009, Hartl 2011). Chaperones, many of which are induced or upregulated only during stress conditions, work in cooperative networks when protein-aggregate concentration