Biologie Chapitre 2 - Molécules du vivant

Study Notes

Molecules of life, or biological molecules, are primarily composed of carbon, hydrogen, oxygen, and nitrogen.
These molecules are vital for carrying out various functions in living organisms.

Atoms are electrically neutral; the number of protons equals the number of electrons.
Isotopes: atoms with the same number of protons but a different number of neutrons.
Ions: atoms that have gained or lost electrons, leading to a positive (cation) or negative (anion) charge.
Chemical bonds (strong and weak) link atoms to form molecules. Strong bonds include covalent bonds (sharing electrons) and ionic bonds (transfer of electrons). Weak bonds, such as hydrogen bonds, are important for molecular interactions.

Water is a crucial molecule in living organisms.
Water is polar, meaning it has a slightly positive and slightly negative end. This polarity allows it to form hydrogen bonds, which are crucial for its unique properties.
Water is a versatile solvent, dissolving many polar and ionic substances, as well as a role in transport.
Water plays a crucial role in regulating temperature due to its high specific heat capacity.
Water also has high cohesion due to the hydrogen bonds between water molecules, which contributes to properties like surface tension.

The four major elements (oxygen, carbon, hydrogen, and nitrogen) make up 99% of the body's mass.
Mineral salts contribute significantly to the body's structures and functions.
Trace minerals are needed in small amounts for normal function.

Organic molecules are primarily composed of carbon and hydrogen.
Carbohydrates, lipids, proteins, and nucleic acids are major types of organic molecules.

Carbohydrates are composed of carbon, hydrogen, and oxygen atoms.
Monosaccharides, disaccharides, and polysaccharides are different forms of carbohydrates.
Carbohydrates serve as a primary energy source for cells.

Proteins are polymers of amino acids.
Proteins have diverse functions, including enzymes, structural components, and hormones.
Proteins are essential for virtually all cellular functions.

Nucleic acids (DNA and RNA) store and transmit genetic information.
Composed of nucleotides, which include a sugar, a phosphate group, and a nitrogenous base.
DNA stores genetic information.
RNA translates and transfers genetic information.