Chemistry of Life: Chapter 2 Notes

Fundamental Building Blocks

• An atom is the fundamental unit of a chemical element, consisting of a nucleus with protons and neutrons, surrounded by electrons.
• Elements are substances whose atoms all have the same number of protons and cannot be broken down chemically.
• Compounds are formed when two or more chemical elements are chemically bonded together.
• Atoms join to form molecules, which are electrically neutral groups of two or more atoms held together by chemical bonds.
• Electrons are arranged around the nucleus in energy levels, which are regions around the nucleus that electrons with a specific range of energies can occupy.
• Atoms have a nucleus with protons and neutrons.
• Protons are stable subatomic particles with a positive electric charge found in the atomic nucleus
• Neutrons are subatomic particles of about the same mass as a proton but without an electric charge, present in the nuclei of atoms
• Electrons are stable subatomic particles with a negative electric charge.
• Energy changes with distance from the nucleus.

Chemical Bonding and Reactions

• Atoms form chemical bonds to achieve atomic stability.
• A chemical bond is an attraction between atoms or ions that allows the formation of chemical substances.
• Ionic bonds involve the transfer of electrons and are formed through an electrostatic attraction between oppositely charged ions.
• Covalent bonds involve the sharing of electrons.
• Hydrogen bonds are weaker bonds based on electromagnetic attraction between a hydrogen atom covalently bonded to a highly electronegative atom and another electronegative atom.
• Electrolytes are substances that produce an electrically conducting solution when dissolved in a polar solvent.
• Ions are charged atoms or molecules in which the total number of electrons is not equal to the total number of protons.
• Electrolytes and ions are significant in biological systems.
• Organic compounds contain carbon and hydrogen atoms covalently bonded together.
• Inorganic compounds do not primarily contain carbon and hydrogen atoms.
• Solvents dissolve solutes, resulting in a solution.
• Solutes are dissolved by solvents in a solution
• A solution is a homogeneous mixture composed of two or more substances.
• Water is a crucial inorganic compound in living organisms.
• A catalyst increases the rate of a chemical reaction without undergoing any permanent chemical change. Enzymes are biological catalysts.
• Hydrolysis is a chemical reaction in which a molecule is cleaved into two parts by the addition of a molecule of water.

Acids, Bases, and pH

• pH measures the acidity or basicity of an aqueous solution
• pH is the negative logarithm (base 10) of the activity of the hydrogen ion (H⁺).
• Lower pH values indicate higher acidity (more H+).
• Higher pH values indicate higher alkalinity (more OH-).
• Alkaline (Basic) solutions have a pH greater than 7, indicating a lower concentration of hydrogen ions (H⁺) and a higher concentration of hydroxide ions (OH⁻).
• Changes in hydrogen and hydroxide ion concentrations affect the acidity or alkalinity of a solution.
• Acidosis is a condition where blood pH is too low. It is characterised by an excessively low pH in the blood and other body tissues.
• Alkalosis is a condition where blood pH is too high and is characterised by an excessively high pH in the blood and other body tissues.

Major Organic Molecules

• Proteins are composed of amino acids linked by peptide bonds. They perform a vast array of functions within living organisms.
• Lipids are composed of glycerol and fatty acids and are insoluble in water but soluble in nonpolar organic solvents.
• Major types of lipids include triglycerides, phospholipids, and steroids.
• Lipids function in energy storage and insulation.
• Carbohydrates are composed of carbon, hydrogen, and oxygen, typically in a ratio of 1:2:1.
• Monosaccharides and polysaccharides are examples of carbohydrates.
• Carbohydrates primarily function in energy storage and serve as a structural component.
• Nucleic acids are complex organic substances present in living cells, made of nucleotides linked in a long chain.
• A nucleotide consists of a nitrogenous base, a sugar molecule (ribose or deoxyribose), and a phosphate group.
• Nucleic acids direct body structure and function through protein synthesis.

Functional Molecules

• Enzymes are biological catalysts that speed up specific chemical reactions in living organisms.
• Enzymes are essential for the body's chemical reactions.
• DNA (Deoxyribonucleic Acid) is a nucleic acid that contains the genetic instructions used in the development, functioning, growth, and reproduction of all known organisms.
• RNA (Ribonucleic Acid) acts as a messenger carrying instructions from DNA for controlling the synthesis of proteins.
• ATP (modified nucleotide) is the primary energy transfer molecule in cells.