Proteins provide mechanical support
Many structural proteins determine the shape of the organ or of a cell and provide mechanical strength that protects soft and delicate organs or cell organelles e.g., bones, collagen fibers, and cytoskeletons.
Functional role:
Enzymes are proteins, that work as biocatalysts, all cellular reactions are catalyzed by enzymes that decrease the energy of activation i.e., the energy barrier. Many proteins help in transportation, such as hemoglobin transports oxygen and CO, gases. red muscles.
Myoglobin is another protein complex that stores oxygen in the Protein molecules and also stores energy in muscles of the body which supply energy to the body when the outside source of food is inadequate such as phosphocreatine.
Proteins also provide immune responses or defense e.g., organisms defend themselves from the harmful effects of pathogens by producing, defense proteins called antibodies within their body. Blood clotting proteins such as fibrinogen and p blood from the body after an injury. Proteins also regulate metabolic processes e.g., hormones. prothrombin, prevent the loss of
Contractility is one of the most outstanding properties of proteins. Contractile muscle proteins (actin and myosin). Tubulin of microtubules (cilia, flagella, and centrioles) helps in the movement of chromosomes during anaphase of cell division caused by proteins (spindle fibers).
2.5 Lipids
Lipids are a heterogeneous group of organic compounds that are insoluble in water but soluble in organic solvents like alcohol, ether, chloroform, acetone, benzene, etc. Lipids have a greasy or oily consistency and include compounds like fats, oils, waxes, cholesterol, and related compounds.
Like carbohydrates, lipids are also composed of C, H, and O. However, the percentage of oxygen in lipids is less than the carbohydrates which makes lipids lighter and make it much less soluble in water than most carbohydrates.
Due to hydrophobic properties, lipids form structures like membranes, act as storage compounds, and possess double energy as compared to carbohydrates due to the high proportion of C-H bonds.
2.5.1 Classification and role of lipids
Lipids are heterogeneous substances and made up of different building blocks. So lipids are classified based on solubility and the products obtained upon hydrolysis. There are the following main groups of lipids.
- Acylglycerol
- Phospholipids
- Terpenes Waxes
Acylglycerol: (Neutral fats):
They are esters of fatty acids and glycerol. They are the most abundant form of lipids in living things. An ester is a compound produced as a result of the chemical reaction of any alcohol with any acid and the release of a water molecule. In the case of acylglycerol alcohol is glycerol. Glycerol is a three-carbon compound having an OH group attached to each carbon atom.
Prostaglandins (PG):
The name prostaglandins is derived from the prostate gland because it was first isolated from seminal fluid in 1935. It was believed to be part of prostatic secretions.
They are a group of physiologically active lipid compounds having diverse hormone-like effects in animals. Prostaglandins have been found in almost every tissue in humans and other animals. They are derived enzymatically from fatty acids. Every prostaglandin contains 20 carbon atoms, including a 5-carbon ring.
In 1971 it was determined that aspirin-like drugs could inhibit the synthesis of prostaglandin. The prostaglandins have a wide variety of effects such as causing dilation and contraction in smooth muscle cells, causing aggregation and disaggregation of platelets, regulating inflammation, regulating hormones, controlling cell growth, sensitizing spinal neurons for pain, acting on the thermoregulatory center of the hypothalamus to regulate fever, etc.
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