Question

In regards to cells:
describe transport processes relative to energy source, substance transported, direction if movement and mechanisms

Answer 1

The simple diffusion is passive mediated transport mechanism that does not require energy. The simple diffusion occurs by transport of substances from a high concentration to low concentration. The substances diffuse through plasma membrane include gases like O₂, CO₂, lipid soluble substances like cholesterol and amino acids and ions etc. The diffusion of water from higher to lower concentration region is called osmosis.

The facilitated diffusion is a type of passive mediated transport and carried out by specific molecules which flow from a high concentration to low concentration. The passive mediated transport carried out by special proteins that carry specific ions or small molecules across the membranes. the proteins include the carrier and channel proteins such as Ionophores, Porins, Ion channels, Aquaporins and transport proteins. All these proteins have specificity for molecules or ions.

The active transport is a process in which a specific molecule is passed from low concentration to high concentration against the concentration gradient. It is an endergonic process as it requires energy to carry out the process. The energy is obtained by the ATP hydrolysis. Several families of ATP - dependent transporters carryout active transport.