Importance of Water in Biology

Study Notes

Water Molecule

Water is a polar molecule due to uneven distribution of charge within the molecule, with hydrogen atoms being more positive than the oxygen atom.
It has a high heat specific capacity, requiring a lot of energy to warm it up, which minimizes temperature fluctuations in living things.
Water has a relatively large latent heat of vaporization, providing a cooling effect with little water loss during evaporation.
Strong cohesion between molecules enables effective transport of water in tube-like transport cells.
Maximum density of water is at 4°C, making ice less dense and causing it to float on top of water, creating an insulating layer.

Monomers and Polymers

Monomers are small units that are components of larger molecules, such as monosaccharides, amino acids, and nucleotides.
Polymers are molecules made from monomers joined together by chemical bonds.
Condensation reactions join monomers by eliminating a water molecule, while hydrolysis is the opposite, breaking a chemical bond between two molecules by adding water.

Carbohydrates

Carbohydrates consist only of carbon, hydrogen, and oxygen and are long chains of sugar units called saccharides.
There are three types of saccharides: monosaccharides, disaccharides, and polysaccharides.
Monosaccharides, such as glucose, can join together to form disaccharides and polysaccharides by glycosidic bonds.

Monosaccharides

Glucose is a monosaccharide containing six carbon atoms, and is the main substrate for respiration.
It has two isomers: alpha and beta glucose.

Disaccharides

Maltose is a disaccharide formed by condensation of two glucose molecules.
Sucrose is a disaccharide formed by condensation of glucose and fructose.
Lactose is a disaccharide formed by condensation of glucose and galactose.

Polysaccharides

Polysaccharides are formed from many glucose units joined together.
Glycogen is the main energy storage molecule in animals, formed from many alpha glucose molecules joined together by 1, 4 and 1, 6 glycosidic bonds.
Starch stores energy in plants, and is a mixture of amylose and amylopectin.
Amylose is an unbranched chain of glucose molecules joined by 1, 4 glycosidic bonds, making it a compact molecule.
Amylopectin is branched, made up of glucose molecules joined by 1, 4 and 1, 6 glycosidic bonds, allowing for rapid digestion by enzymes.

Description

Learn about the significance of water in biological systems, including its role as a polar molecule, metabolite, and solvent in metabolic reactions. Explore how water facilitates the formation and breaking of chemical bonds.