membrane structures and function

These membranes are formed outside the embryo from the trophoblast and perform specific functions..

Plasma Membrane - The plasma membrane or cell membrane surrounds the cell contents in all types of cells. It is a multipurpose covering composed of phospholipids and proteins. fig. 16.4 - Cell Membrane Apart from the plasma membrane, an eukaryotic c..

>Each alveolar duct opens into an alveolar sac. Alveolar sac is the extended region into which a group of alveoli or air sacs open. Each alveolus is a sac-like structure lined by a single layer of epithelial cells. It is bound on the outside by a network of capillaries. All the alveoli on..

The human heart is a muscular, cone-shaped, hollow organ about the size of a fist (about 12cm in length and 9cm in breadth). The heart is situated behind the sternum, between the lungs in the thoracic cavity. The heart is tilted slightly such that its apex is towards the left side. The major p..

The molecular structure of cell membrane is still not clearly known. Several models have been proposed from time to time to explain its structure based on its physico-chemical properties. In the year 1935 Danielli and Dawson proposed that the cell membrane is..

It is present in both plant and animal cells. It is living, elastic and made of proteins and lipids (fats). Its function is to provide a mechanical barrier for the protection of the inner cell contents and to regulate the movement of molecules in and out of the cel..

The molecular structure of cell membrane is still not clearly known. Several models have been proposed from time to time to explain its structure based on its physico-chemical propertie..

) or secretory products (gums, alkaloids, hormones, etc) or excretory products (calcium carbonate and other salts). These substances are generally stored in the vacuoles. Cell organelles are mainly of two types membrane-bound and non-membranous. Membrane bound organell..

The characteristic structure of an ecosystem is obtained by the systematic physical organisation of the abiotic and biotic components of that particular ecosystem. The two main structural features of any ecosystem are its 'species composition' and 'stratification'. An ecosystem ..

Structure of Functional Groups - In alcohol, the oxygen of the -OH group is attached to sp 3 hybridized carbon by a sigma ( s ) bond formed by the overlap of sp 3 hybrid orbital of carbon with an sp 3 hybrid orbital of oxygen. in alcohols is slightly less than the tetrahedral an..