Membrane

Ion channels are membrane proteins that selectively allow the permeation of ions into and out of cells (Fig.1a ###image messes with formatting). Some channels have evolved to also sense changes in the electrical potential across a membrane. A potential above a certain voltage will trigger the opening of these ion-conducting pores, releasing large stores of ions across the membrane. These voltage-gated ion channels allow for the generation of electrical stimuli (the firing of neurons via the…

of peptidoglycan that is enclosed by an outer membrane. The outer membrane is surrounded by special phospholipids composed of fatty acids called lipopolysaccharides that are attached to a glucosamine…

Receptors are protein molecules that receive chemical signals in the form of ligands and induce responses at cellular level. They are localized at the cell surface, cytoplasm or the nucleus, depending on their amino acid sequences. In addition to using these three different localizations to categorize receptors, the types of action of receptors are also used as a mean of classification. The four main classifications of receptors are: 1. Ionotropic (or ligand-gated ion channel) receptors, 2.…

All things alive are made of cells. We humans have way too many to count. All the cells cluster and act together in the way so that we can function normally. Thanks to Agre and MacKinnon we now have more knowledge over molecular machines such ass channels, gates, and valves. The fact that water could go through the cell wall has always been a known thing, however, how the pores looked under function had been unknown. That is, until 1990 when Agre became the first to discover one. Chemical…

pressure through a semi-permeable membrane. To understand the purpose and the process of Reverse Osmosis, should understand the natural Osmosis operation. Natural Osmosis: The phenomenon of osmosis occurs when pure water flows from a dilute saline solution through a membrane into a higher concentrated saline solution. (Example of osmosis is our kidneys absorb water from our blood). Figure (A): Natural osmosis operation principle. (Zahid amjad) A semi-permeable membrane is placed between two…

In the fifth chapter of Biology, Peter Raven and George Johnson demonstrate the pedagogical functionality of metaphor by “highlighting” (Kövecses 91) the biological function of cell membranes through the underlying descriptive structural megametaphors CELL MEMBRANE IS A WALL and TRANSPORT PROTEINS ARE DOORS and the mappings between them, and by “hiding” (Kövecses 92) other aspects of this concept. Throughout this chapter, Peter Raven and George Johnson pair these main conceptual…

Tympanic Membrane Perforation A tympanic membrane perforation is a hole in your eardrum. The eardrum is a thin sheet of tissue that separates your middle ear from your ear canal. It protects your middle ear from germs that can cause infection. A tympanic membrane perforation can cause ear pain and hearing loss. CAUSES This condition may be caused by: An injury, such as: A blow to the side of the head. A fall onto water or a flat surface. Too much pressure on the eardrum,…

Mitochondria are surrounded by a double-membrane system, consisting of inner and outer mitochondrial membranes separated by an intermembrane space. (Cooper, 2000). It has the outer membrane and the inner membrane. The membranes are made up of phospholipids and proteins. The mitochondria has an outer membrane which is smooth and composed of equal amounts of phospholipids and proteins. It has a large number of special proteins known as the porins. The porins are integral membrane proteins and…

floats. The bilayer is also formed as a result of the nonpolar regions of the membrane proteins and phospholipids coming together to make a shield that is insoluble. In a membrane, the hydrophilic proteins are exposed/on the outside while the hydrophobic r on the inside. The outside membrane protein's job is to receive signals and regulate traffic. Carbs attached to the proteins also help with this. Lipids within membranes are usually phospholipids and they have both water loving/hating regions.…

ways that it allows molecules and ions to cross its membrane, including bulk transport, osmosis, passive transport, and active transport. The purpose of the cell membrane is to protect the cell and only allow specific substances to cross the membrane, such as amino acids or water. Lipids hold the membrane together, along with proteins and carbohydrates. These lipids are saturated or unsaturated, and have a hydrophilic head. The tails hold the membrane together due to their fear of water.…