Macromolecules and Water Living Organisms Elements – Atomic Structure Nucleus – Chemical Activity – Chemical Bonds Ionic – Covalent – Hydrogen – Van der Waals Forces – Macromolecules of Life Carbohydrates – Lipids – Nucleic Acids – Proteins – Enzymes – Water Polarity – Properties Essential to Life -

Learning Goal 3 Identify the function and properties of the four major macro-molecules and water.

Elements of Living Organisms Carbon, hydrogen, oxygen, and nitrogen make up 96% of the weight of living organisms.

Atomic Structure The Atomic Nucleus Contains protons and neutrons. Protons are positive and neutrons are neutral. Electrons orbit the nucleus and carry a negative charge.

Chemical Activity and Electrons Electrons in an atom’s outermost energy level are known as valence electrons. Atoms will form bonds to fill their outer level with a stable number of electrons. This number is usually 8.

Chemical Bonds Ionic Bonds Form between atoms that gain or lose valence electrons completely. This causes the atoms involved to become charged.

Covalent Bonds Covalent bonds form when atoms share a pair of valence electrons rather than gaining or losing them.

Hydrogen Bonds When hydrogen atoms (the smallest atoms) share electrons with larger atoms like oxygen or nitrogen, the larger atoms have a stronger pull on the electrons. This creates a partially positive charge at the hydrogen atoms which will form weak bonds with the partially negative charge at the larger atom of other molecules.

Van der Waals Forces These are forces of attraction between molecules that are even weaker than hydrogen bonds. They develop between nonpolar molecules when electrons accumulate in one part of the molecule or another.

Macromolecules of Life Carbohydrates Composed of glucose monomers, that are 25% carbon, 50% hydrogen, 25% oxygen. Used in cells as fuel to produce energy and provide structural support Examples: glucose, starch, cellulose

Carbohydrates Can be very large, complex molecules made up of many monomers.

Lipids Composed of glycerol and fatty acid molecules. Approximately 30% carbon, 60% hydrogen, 10% oxygen. Function in energy storage, cell membrane and some hormone structures. Examples: fats, oils, cholesterol, steroids, phospholipids.

Nucleic Acids Made up of nucleotide monomers that consist of approximately 25% each of carbon, hydrogen, and oxygen with about 12% each of nitrogen and phosphorus. Function in storing and transmitting genetic information and energy supply. Examples: DNA, RNA, ATP

Proteins Composed of amino acid monomers approximately 50% carbon, 35% hydrogen, 10% oxygen and 5% nitrogen, with trace amount of other elements. Used for many metabolic reactions such as digestion, chemical signals, and structural components in muscle and other tissues. Example: amylase (starch digestion), collagen (structural), insulin (signal)

Enzymes Important class of proteins needed for all metabolic reactions. Lower the energy needed for reactions to take place. Very specific to reactions they catalyze.

Water Polarity: Positive parts of the molecules attract to negative parts of other water molecules forming hydrogen bonds. Properties Essential to Life: 1. resists temperature change 2. exhibits adhesion and cohesion 3. it’s the universal solvent 4. freezes in a less dense state than when it is liquid

Water Cohesion Adhesion Capillary Action