The PNS helps to maintain internal balance, or "homeostasis," by the Parasympathetic division of the Autonomic Nervous System (ANS). Sometimes referred to as the "rest and digest" system, the Parasympathetics keep our internal activities regular throughout the day and night, such as a steady heart rate, slow breathing, digestion of food, filtration of blood, and excretion of wastes.
As food passes through the GI tract, it mixes with digestive juices, causing large molecules of food to break down into smaller molecules. The body then absorbs these smaller molecules through the walls of the small intestine into the bloodstream, which delivers them to the rest of the body.
Answer:
1. P120 is degraded in the 26S proteasome
2. The 26S proteasome has a major role in protein degradation and is critical for protein homeostasis
3. Cell cycle and DNA replication are cellular processes regulated by the Ras and NFkB pathways
Explanation:
The proliferation-associated nucleolar protein (p120) is a protein known to be expressed during the interphase of the cell cycle, specifically in G1 and early S phase, where any problem with DNA replication trigger a checkpoint, i.e., a molecular cascade of signaling events that suspend DNA replication until the problem is resolved. In mammalian cells, the 26S proteasome is responsible for catalyzing protein degradation of about 80% (or even more) of their proteins. The 26S proteasome acts to degrade rapidly misfolded and regulatory proteins involved in the cell cycle, thereby having a major role in protein homeostasis and in the control of cellular processes. It is for that reason that inhibitors that block 26S proteasome function have shown to be useful as therapeutic agents in diseases associated with the failure of protein degradation mechanisms (e.g., multiple myeloma). The NF-κB are highly conserved transcription factors capable of regulating different cellular processes including, among others, cellular growth, inflammatory responses and apoptosis. Moreover, the MAPK/ERK pathway is able to transduce different signals received on the cell surface to the nucleus. The MAPK/ERK pathway is activated when a singling molecule binds to a cell receptor which triggers a signaling cascade that ends when a transcription factor induces the expression of target genes, ultimately producing a response in the cell (for example, the progression through the cell cycle).
One example of passive transport is diffusion, when molecules move from an area of high concentration (large amount) to an area of low concentration (low amount). Molecules are said to naturally flow down their concentration gradient
