Peroxisomes are membrane–bound sacs containing enzymes such as peroxidase and catalase. These enzymes catalyse and breakdown the hydrogen peroxide. These enzymes are involved in oxidation and reduction reactions also. Peroxisomes occur largely in hepatic and renal cells. Marker enzyme is catalase.
The location and integration of metabolic pathways are released by studies at lower levels of organisation, namely the following: At the tissue and organ level, the blood circulation integrates metabolism. Amino acids resulting from digestion of dietary protein and glucose resulting from the digestion of carbohydrate share a common route of absorption via the hepatic…
Golgi bodies are very similar to ER in structure and function. They are made of a double membrane. The structure of Golgi bodies is as shown in Figure 1.7. Proteins produced by the ribosomes are stored in the form of secretory. Proteins and enzymes are enclosed in the vesicles of Golgi bodies. Golgi bodies are involved in…
These are subcellular organelles, approximately of the same size as small mitochondria. They are bound by a membrane and appear as bags filled with digestive enzymes such as ribonuclease, glycosidase, acid phosphatase, and aryl sulphates. The structure of lysosome is as shown in Figure 1.6. As long as the membrane of lysosome remains intact, the enzymes…
Amino acids are necessary for protein synthesis. Some must be supplied specifically in the diet (the essential amino acids) since the tissues are unable to synthesis them. The reminder or non-essential amino acids are also supplied in the diet, but they can be formed from intermediates by transamination using the amino nitrogen from other surplus…
The source for the fatty acid synthesis is acetyl-CoA. Fatty acid is produced either by de novo synthesis from acetyl-CoA derived from carbohydrate or from dietary lipid. In the tissues, fatty acids are oxidised to acetyl-CoA (β-oxidation) or esterified to acylglycerol, whereas in triacylglycerol (fat), they constitute the body’s main caloric reserve. Acetyl-CoA formed by…
A large portion of the ER is grouped with ribosomes, which are the factories of protein synthesis. Ribosomes are also enriched with lipids, particularly phospholipids. Ribosomes consist of particles of two sizes: one with a sedimentation constant of 50S and the other with 30S. The two particles combine to give one with a sedimentation constant…
Endoplasmic reticulum (ER) is a complex system of membranes present in cytoplasm. It is a network of lipoprotein membranes in the form of flattened sacs, tubules, and vesicles, enclosing a space called intracisternal space. Two types of ER are seen: (a) smooth ER without any attached particles and (b) rough (granular) ER with spherical particles…
Mitochondria are the largest organelles in cytoplasm. They are spherical, oval, or rod-like bodies, about 0.5 μm – 1.0 μm in diametre and up to 7 μm in length. The structure of mitochondria is shown in Figure 1.4. Mitochondria are considered to be the power houses of the cell because energy is released from oxidation that…
Nucleus is the largest cellular organelle. It is spherical in shape, with a diameter of about 5 μM. Nucleus is surrounded by a nuclear membrane. The nuclear membrane is porous in nature and the pores are called nuclear pores. The RNA synthesised in the nucleus enters into the cytoplasm through these nuclear pores. Nucleus consists…