Osmosis is the diffusion of a solvent across a selectively permeable membrane. Osmotic pressure is a measure of the tendency of water (or solvent) to move across the selective permeable membrane. Iso-osmotic solutions have the same concentration of solute particles. Hyperosmotic solutions have higher concentration, and hypo-osmotic solutions have lower concentration of solute particles than…

Diffusion Diffusion is the movement of a substance from an area of high concentration to an area of low concentration (down a concentration gradient). The concentration gradient is the difference in solute concentration between two points divided by the distance separating the points. The rate of diffusion increases with an increase in the concentration gradient,…

Lipid-soluble molecules pass through the plasma membrane readily by dissolving in the lipid bilayer. Small molecules pass through membrane pores. The pores are positively charged and allow anions, and neutral molecules pass through more readily than cations. Large polar substances (e.g. glucose and amino acids) are transported through the membrane with the help of carrier…

CELL MEMBRANE Cell is enveloped by a thin membrane called cell membrane or plasma membrane which allows only selective passage of substances. Membranes are made up of lipids, proteins, and small amounts of carbohydrates. Different membranes have different ratios of protein and lipid. Proteins in the cell membrane are of two types: peripheral proteins and…

Cell is the fundamental unit of living things. It is defined as the basic unit of biological activity. The word cell was contributed by Schieiden and Schwann (1838). Cell is microscopic in nature. It is composed of an outer plasma membrane, cytoplasm, Golgi bodies, mitochondira, endoplasmic reticulum, ribosomes, microtubules, microfilaments, lysosome, and nucleus. The plasma…

Cell is considered to be the smallest unit of life. It is self-sufficient such that all kinds of cells can survive independently. There are several differences between an animal cell and a plant cell. Most cells have organelles, which are sub-cellular parts that perform specific functions. These sub-cellular parts (organelles) help the cell to efficiently…