Mediated transport is the transport of molecules across the membrane with the help of a carrier. The molecule transported may be large and water soluble. The carriers have the capacity to bind either a single molecule or a group of similar molecules. This process is known as specificity. Similar molecules bind to the same carrier.…
Glucose is metabolised to pyruvate and lactate in all mammalian cells by the pathway of glycolysis. Phosphorylation is necessary for glucose to enter this pathway. Glycolysis can occur in the absence of oxygen (anaerobic) when the end product is lactate only. Tissues that can utilise oxygen (aerobic) are able to metabolise pyruvate to acetyl-CoA, which…
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…
It is the biosynthetic reaction involving the formation of complex molecules from simpler precursors. For the synthesis of a large variety of complex molecules, the starting materials are relatively few. These include pyruvate, acetyl-CoA, and the intermediates of citric acid cycle. Besides the availability of precursors, the anabolic reactions depend on the supply of energy…
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…
CATABOLISM Catabolism is defined as the degradative process concerned with the breakdown of complex molecules to simpler ones, with a release of energy. The very purpose of catabolism is to trap the energy of the biomolecules in the form of ATP and generate the substances (precursors) required for the synthesis of complex molecules. Catabolism occurs…
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…
The term metabolism is defined as the entire of spectrum of chemical reactions that occur in the living system. A metabolic pathway consists of a series of enzymatic reactions to produce desired products. The term metabolite is applied to a substrate or an intermediate or a product in metabolic reactions. Metabolism is broadly divide into two categories: catabolism…
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…