Golgi and centrosome during cell cycle



The endomembrane system plays a very important role in moving materials around the cell, notably proteins and membranes (the latter is called membrane trafficking).

c. An area where the nucleus is synthesized

Contains cellular molecules, macromolecules such as enzymes, lipids, carbohydrates, and RNA

d. Membrane lipids are produced by that cell.

Dispersed in the cytoplasm, and also present in conjunction with the rough ER, they are responsible for synthesizing the proteins required for various cellular processes.

Organelle involved with lipid synthesis and drug ..

Place 2-3 such sets of belts in the jello cytoplasm to show the of the cell.

Golgi apparatus is another intricate network of membranous stacks, and is involved in protein modification.

This membrane blocks uncontrolled movements of water-soluble materials into or out of the cell.
Smooth ER is devoid of ribosomes, and is the site for lipid synthesis and protein transport.

it's involved with lipid synthesis.

Endocytosis is a key process that uses budding vesicles to selectively remove lipids and proteins from the plasma membrane, counterbalancing secretion, and contributing heavily to the control of plasma membrane composition (). Endocytosis also acts as a key portal by which cells take in macromolecules from the outside environment, such as nutrients and intercellular signals, typically through interaction with endocytic receptors. Endocytic uptake can be clathrin-dependent, mediated by the budding of clathrin-coated vesicles, or through a variety of poorly understood clathrin-independent vesicle budding events (). Once internalized, primary endocytic vesicles fuse with endosomes, and extensive sorting processes within endosomes determine the final destination of cargo molecules (; ). In endocytosis has been studied most extensively in oocytes, early embryos, coelomocytes, and polarized epithelial cells of the intestine. The intestine is a polarized single layer epithelium, whereas the coelomocyte and the oocyte are generally considered to be non-polarized (see WormBook chapters and ). Polarized cells, such as epithelia and neurons, maintain two completely distinct plasma membrane domains (e.g., apical versus basolateral and axon versus dendrite), which places extra demands upon the secretory and endocytic machinery ().

4. DNA (at some point in their life cycle), a cell membrane, and cytoplasm

A ribosome is the site of protein synthesis in the cell

RME-1 was first discovered in the yolk transport screens, with null mutants displaying poor endocytosis of YP170::GFP (). Further investigation revealed that poor yolk uptake was due to poor recycling of the yolk receptor RME-2 in oocytes. It was also noted that all mutants displayed an unselected phenotype, progressive vacuolization of the intestine that included formation of vacuoles large enough to recognize at the level of the dissecting microscope. Subsequent work showed that these enlarged organelles labeled for ARF-6 but not RAB-5, accumulated several basolateral cargo proteins including hTAC and hTfR, and filled with basolaterally applied fluid-phase endocytosis markers but not endocytosed lipophilic dye FM 4-64 (; ). These results indicated that RME-1 regulated a late step in basolateral recycling. RME-1 protein labeled a tubulovesicular network of endosomes just below the basolateral surface that resembled the endocytic recycling compartment (recycling endosomes) in mammalian cells () (; ; ). Analysis in mammalian cells showed that the RME-1 homolog EHD1 localized to the endocytic recycling compartment and was required for recycling endosome to plasma membrane transport (; ). The basolateral recycling defects of mutants, but not of mutants, can be suppressed by loss of the PTB domain protein NUM-1/Numb. Current models indicate that NUM-1 is a negative regulator of recycling, although its mechanism is not known ().

72. A protein molecule is to be exported from the cell. Describe the pathway that the protein takes from the point of synthesis to export.

Which are the cell organelles that produce protein? - …

In the early embryo CAV-1 and RME-2 on the cell surface are normally internalized and degraded shortly after fertilization (, ). The loss of the ESCRT-I or ESCRT-III-associated protein ALX-1 leads to a significant delay in the degradation of internalized cell surface proteins such as CAV-1 and RME-2 in embryos and the degradation of LIN-12 in the larval vulval precursor cell (; ; ). Depletion of ESCRT-I components results in the loss of VPS-32 from the endosomal membrane, suggesting that ESCRT-I is required for the recruitment of ESCRT-III to the endosomal membrane (). In the absence of VPS-4, the ESCRT-I and ESCRT-III components over-accumulate on endosomal membranes, suggesting that the requirement for VPS-4 in ESCRT disassembly and dissociation from endosomal membrane is conserved in (; ). Consistently, knockdown of inhibits the degradation of CAV-1 in the early embryo and LET-23 in the late embryo, and leads to the accumulation of enlarged endosomes (). Loss of all four oxysterol-binding protein-related proteins (ORPs) produced similar phenotypes and is additive with RNAi (). ORPs transfer cholesterol between organellar membranes, suggesting that the endosomal cholesterol is required for normal MVB formation/function ().