Semipermeable membrane

Tetrahymena contractions with different solutions Purpose: How fast will the Tetrahymena contractile vacuole contract in different solutions? Introduction: In this experiment, the organism that is used are the Tetrahymena. The Tetrahymena has a contractile vacuole that protects them from absorbing too much water, causing cytolysis, in which a cell swells up and could result in explosion of the cell. The contractile vacuole expands when water enters it and contracts to release water to maintain…

There are two major classifications of living things, plants and animals, and all species that are under these two kingdoms are required to have proper functions of their body processes to survive. The most important in all of the body processes is the transport system, it is the one that is responsible for well being of all other body systems to function smoothly and properly by supplying nutrients for it to live.These organisms need to have the ability to transport particles such as molecules…

1935, the first plasma membrane structure model was introduced by Danielli and Davson. They proposed that the membrane is made of phospholipid bilayer that consists of hydrophobic head and the hydrophilic tail. Hydrophilic head, which is polar, facing towards the water molecules and said to be coated with protein. Hydrophilic tail, which is non-polar is not facing water molecules and sandwiched between the two bilayers. At regular intervals of the surface of the plasma membrane, there are also…

4.2 RES as activator of sirtuins and other biological target structures There are several molecular activities discussed that should convey the health-promoting effects of RES. In one of the most important (if not the decisive one) study, it was shown that RES modulates the activity of the silent mating type information regulation 2 homolog 1 (SIRT1) (3). SIRT1 belongs to a protein family consisting of seven (SIRT1-SIRT7) individual members that are unique Nicotinamide adenine dinucleotide…

while eliminating wastes that could be harmful to them. The cell membrane is also known as the phospholipid bilayer because of the fact that there are two layers formed by phospholipid molecules. The phospholipid has a phosphate and a lipid portion. "The phospholipids lie with their hydrophilic heads at the membrane surface and their hydrophobic tails on the inside..." (Anatomy and Physiology Textbook 66) There are two general membrane proteins, including the integral proteins, also known as…

integral membrane-spanning protein that moves the neurotransmitter dopamine out of the synapse back into cytosol terminating therefore the signal of the neurotransmitter. The dopamine reuptake via DAT is the primary mechanism from which dopamine is cleared from synapses. Its function requires the binding and cotransport of two Na+ ions and one Cl− ion with the dopamine substrate. The driving force for DAT-mediated dopamine reuptake is the ion concentration gradient generated by the plasma…

Structure of Tight Junctions and their Dynamic Functions in Health and Disease Tight junction (TJ) discovery in the 1960s helped determine the nature of paracellular transport while the discovery of their constituting proteins subsequently improved understanding of TJs’ dynamic structure. Their role can be appreciated particularly in epithelial cells and when their formation is compromised; I aim to briefly explore the cause of Crohn’s disease to illustrate this. Furthermore, I will outline the…

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…

Why the system is important? The purpose of osmoregulation is to maintain a constant, optimal osmotic pressure within the body or cell. (Biology online, 2009). It allows the body to maintain a suitable concentration of solutes and of water in body fluids. Water is needed in the body for the reasons mentioned above such as providing trasport of substances, acting as a solvent and for use in evaporative cooling mechanisms. This means as humans we must maintain an optimum level of water in the…

INTRODUCTION A membrane of the cell is the defensive wall that protects, controls and regulate the amount of ions and water that enter and exit it. While some substances, such as, water, can enter and exit the cell through osmosis, others have to be transported more in some systematic ways, such as, packing or transporting different ions through protein molecule. (Flinders (2016)) Knowing the permeability of a cell membrane helps scientists on many circumstances. One of them is how much…