Chemistry of Life

Nature of Matter

Matter- Anything that has Mass and Volume

• Atoms are the smallest unit of matter that cannot be broken down by chemical means

• Atoms consist of protons, electrons, and neutrons (symbols, atomic #, atomic mass)

• Elements are pure substances that are made of only one kind of atom. A chunk of gold is made up of only gold atoms

• Isotopes- atoms that have different number of neutrons (ie. Carbon 14)

Chemical Bonding

• Bonding is a force that joins atoms together

• Compounds are substances that consist of 2 or more elements joined together

• 3 types of chemical bonds (covalent, hydrogen, & ionic)

Bonding

• Covalent bonds form when 2 or more atoms share electrons

• Hydrogen bonds form when there is a weak chemical attraction between polar bodies

• Polar bodies-unequal distribution of electrical charges

• Ionic bonds form when an atom or molecule gains or loses electrons

Water in Living Things

• Water is the medium in which most cellular events take place

• Water can store heat

• Water is used to cool body (sweat)

• Water helps maintain homeostasis

Cohesion/Adhesion

• Cohesion is an attraction between substances of the same kind (water drops on penny)

• Adhesion is the attraction between different substances (think adhesive tape)

• Adhesion powers capillary action in plants

Solutions

• A solution is a mixture in which one or more substances are evenly distributed in another substance

• Solvent -water• Solute - salt• Solubility - the amount of solute that dissolves in solvent

Acidity - pH

• Acids- compounds that form hydrogen ions (H+) when dissolved in water

• Bases- compounds that form hydroxide (OH-) ions when dissolved in water

• 0 - 6.9 = acid • 7.1 - 14 = base• 7 = neutral

Chemistry of Cells

• Organic compounds contain carbon atoms

• 4 classes of organic compounds that are found in living things are: carbohydrates, lipids, proteins, and nucleic acids

Carbohydrates

• Consist of carbon, hydrogen and oxygen (1-2-1 ratio)

• Key source of energy and are found in most foods (grains, fruits)

• Simple sugars make up carbohydrates

• Mono, di, polysaccharides

Lipids

• Nonpolar molecules that are not soluble in water

• Fats, phospholipids, steroids, and waxes

• Lipids are an important part of the cell membrane

• Fats are lipids that store a lot of energy

• Fats consist of 3 fatty acids bonded to glycerol

Proteins

• Large molecules formed by amino acids

• 20 different a.a.• Enzymes are made of amino acids-help with chemical reactions

• Examples of proteins:– Collagen, antibodies, hemoglobin

Nucleic Acids

• Nucleic acids are found in cells - genes

• Nucleic acids are made of nucleotides (sugar, base, and phosphate group)

• 2 types of nucleic acids - DNA & RNA

• ATP - single nucleotide with 2 extra storing phosphate groups (energy released in respiration)

Energy and Chemical Reactions

• Energy can be stored or released by chemical reactions

• Chemical bonds b/w atoms are broken and new ones are formed

• Reactants- starting materials

• Products- ending materials

• Energy can either be released or absorbed during chemical reactions (page 39)

• Endo vs. exothermic

• Activation energy is the energy needed to start a chemical reaction

Enzymes

• Enzymes increase the speed of chemical reactions (most are proteins)

• Enzymes are catalyst, which are substances that reduce the activation energy

• Enzymes help maintain homeostasis by increasing chemical reaction speed

• Enzymes act only on specific substrates (specific shape determines activity) page 41

• The rate in which enzymes work can be influenced by temperature and pH.